Giovanni Domenico Cassini (8 June 1625 – 14 September 1712) was an Italian mathematician, astronomer, engineer, and astrologer. Cassini, also known as Gian Domenico Cassini, was born in Perinaldo, near Imperia, at that time in the County of Nice under the control of the Republic of Genoa. Cassini is known for his work in the fields of astronomy and engineering. Cassini most notably discovered four satellites of the planet Saturn and noted the division of the rings of Saturn (with the Cassini Division becoming named after him). Giovanni Domenico Cassini was also the first of his family to begin work on the project of creating a topographic map of France. Launched in 1997, the Cassini spaceprobe was named after him and became the fourth to visit Saturn and the first to orbit the planet.
Comet Shoemaker–Levy 9 (formally designated D/1993 F2) was a comet that broke apart and collided with Jupiter in July 1994, providing the first direct observation of an extra-terrestrial collision of Solar System objects. This generated a large amount of coverage in the popular media, and the comet was closely observed by astronomers worldwide. The collision provided new information about Jupiter and highlighted its role in reducing space debris in the inner Solar System.
The comet was discovered by astronomers Carolyn and Eugene M. Shoemaker and David Levy. Shoemaker–Levy 9, at the time captured by and orbiting Jupiter, was located on the night of March 24, 1993, in a photograph taken with the 40 cm (16 in) Schmidt telescope at the Palomar Observatory in California. It was the first comet observed to be orbiting a planet, and had probably been captured by the planet around 20 – 30 years earlier.
Calculations showed that its unusual fragmented form was due to a previous closer approach to Jupiter in July 1992. At that time, the orbit of Shoemaker–Levy 9 passed within Jupiter’s Roche limit, and Jupiter’s tidal forces had acted to pull apart the comet. The comet was later observed as a series of fragments ranging up to 2 km (1.2 mi) in diameter. These fragments collided with Jupiter’s southern hemisphere between July 16 and July 22, 1994, at a speed of approximately 60 km/s (37 mi/s) or 216,000 km/h (134,000 mph). The prominent scars from the impacts were more easily visible than the Great Red Spot and persisted for many months.
While conducting a program of observations designed to uncover near-Earth objects, the Shoemakers and Levy discovered Comet Shoemaker–Levy 9 on the night of March 24, 1993 in a photograph taken with the 0.4 m (1.3 ft) Schmidt telescope at the Palomar Observatory in California. The comet was thus a serendipitous discovery, but one that quickly overshadowed the results from their main observing program.
Comet Shoemaker–Levy 9 was the ninth periodic comet (a comet whose orbital period is 200 years or less) discovered by the Shoemakers and Levy, hence its name. It was their eleventh comet discovery overall including their discovery of two non-periodic comets, which use a different nomenclature. The discovery was announced in IAU Circular 5725 on March 27, 1993.
The discovery image gave the first hint that comet Shoemaker–Levy 9 was an unusual comet, as it appeared to show multiple nuclei in an elongated region about 50 arcseconds long and 10 arcseconds wide. Brian G. Marsden of the Central Bureau for Astronomical Telegrams noted that the comet lay only about 4 degrees from Jupiter as seen from Earth, and that while this could of course be a line of sight effect, its apparent motion in the sky suggested that it was physically close to the giant planet. Because of this, he suggested that the Shoemakers and David Levy had discovered the fragments of a comet that had been disrupted by Jupiter‘s gravity.
Orbital studies of the new comet soon revealed that it was orbiting Jupiter rather than the Sun, unlike all other comets known at the time. Its orbit around Jupiter was very loosely bound, with a period of about 2 years and an apojove (the point in the orbit farthest from the planet) of 0.33 astronomical units (49,000,000 km). Its orbit around the planet was highly eccentric (e = 0.9986).
Tracing back the comet’s orbital motion revealed that it had been orbiting Jupiter for some time. It seems most likely that it was captured from a solar orbit in the early 1970s, although the capture may have occurred as early as the mid-1960s. Several other observers found images of the comet in precovery images obtained before March 24, including Kin Endate from a photograph exposed on March 15, S. Otomo on March 17, and a team led by Eleanor Helin from images on March 19. No precovery images dating back to earlier than March 1993 have been found. Before the comet was captured by Jupiter, it was probably a short-period comet with an aphelion just inside Jupiter’s orbit, and a perihelion interior to the asteroid belt.
The volume of space within which an object can be said to orbit Jupiter is defined by Jupiter’s Hill sphere (also called the Roche sphere). When the comet passed Jupiter in the late 1960s or early 1970s, it happened to be near its aphelion, and found itself slightly within Jupiter’s Hill sphere. Jupiter’s gravity nudged the comet towards it. Because the comet’s motion with respect to Jupiter was very small, it fell almost straight toward Jupiter, which is why it ended up on a Jupiter-centric orbit of very high eccentricity – that is to say, the ellipse was nearly flattened out.
The comet had apparently passed extremely close to Jupiter on July 7, 1992, just over 40,000 km (25,000 mi) above the planet’s cloud tops – a smaller distance than Jupiter’s radius of 70,000 km (43,000 mi), and well within the orbit of Jupiter’s innermost moon Metis and the planet’s Roche limit, inside which tidal forces are strong enough to disrupt a body held together only by gravity. Although the comet had approached Jupiter closely before, the July 7 encounter seemed to be by far the closest, and the fragmentation of the comet is thought to have occurred at this time. Each fragment of the comet was denoted by a letter of the alphabet, from “fragment A” through to “fragment W”, a practice already established from previously observed broken-up comets.
More exciting for planetary astronomers was that the best orbital calculations suggested that the comet would pass within 45,000 km (28,000 mi) of the center of Jupiter, a distance smaller than the planet’s radius, meaning that there was an extremely high probability that SL9 would collide with Jupiter in July 1994. Studies suggested that the train of nuclei would plow into Jupiter’s atmosphere over a period of about five days.
Proxima Centauri (Latin proxima, meaning “next to” or “nearest to”) is a red dwarf about 4.24 light-years from the Sun, inside the G-cloud, in the constellation of Centaurus. It was discovered in 1915 by Scottish astronomer Robert Innes, the Director of the Union Observatory in South Africa, and is the nearest known star to the Sun, although it is too faint to be seen with the naked eye, with an apparent magnitude of 11.05. Its distance to the second- and third-nearest stars, which form the bright binary Alpha Centauri, is 0.237 ± 0.011 ly (15,000 ± 700 AU). Proxima Centauri is very likely part of a triple star system with Alpha Centauri A and B, but its orbital period may be greater than 500,000 years.
Because of the proximity of this star, its distance from the Earth and angular diameter can be measured directly, from which it can be determined that its diameter is about one-seventh of that of the Sun. Proxima Centauri’s mass is about an eighth of the Sun’s (M☉), and its average density is about 40 times that of the Sun. Although it has a very low average luminosity, Proxima is a flare star that undergoes random dramatic increases in brightness because of magnetic activity. The star’s magnetic field is created by convection throughout the stellar body, and the resulting flare activity generates a total X-ray emission similar to that produced by the Sun. The mixing of the fuel at Proxima Centauri’s core through convection and the star’s relatively low energy-production rate suggest that it will be a main-sequence star for another four trillion years, or nearly 300 times the current age of the universe.
Searches for companions orbiting Proxima Centauri have been unsuccessful, ruling out the presence of brown dwarfs and supermassive planets. Precision radial velocity surveys have also ruled out the presence of super-Earths within the star’s habitable zone. The detection of smaller objects will require the use of new instruments, such as the James Webb Space Telescope, which is scheduled for deployment in 2018. Because Proxima Centauri is a red dwarf and a flare star, whether a planet orbiting it could support life is disputed. Nevertheless, because of the star’s proximity to Earth, it has been proposed as a destination for interstellar travel.
It’s Found in Sagittarius
As seen from the northern hemisphere, the constellation’s brighter stars form an easily recognizable asterism known as ‘the Teapot‘. The stars δ Sgr (Kaus Media), ε Sgr (Kaus Australis), ζ Sgr (Ascella), and φ Sgr (Nanto) form the body of the pot; λ Sgr (Kaus Borealis) is the point of the lid; γ2 Sgr (Alnasl) is the tip of the spout; and σ Sgr (Nunki) and τ Sgr (the closest bright star to the possible origin of the Wow! signal) the handle.
To complete the teapot metaphor, under good conditions, a particularly dense area of the Milky Way can be seen rising in a north-westerly arc above the spout, like a puff of steam rising from a boiling kettle.
The constellation as a whole is often depicted as having the rough appearance of a stick-figure archer drawing its bow, with the fainter stars providing the outline of the horse’s body. Sagittarius famously points its arrow at the heart of Scorpius, represented by the reddish star Antares, as the two constellations race around the sky. Following the direct line formed by Delta Sagittarii (δ Sgr) and Gamma Sagittarii (γ Sgr) leads nearly directly to Antares. , Fittingly, Gamma Sagittarii is named Alnasl, the Arabic word for “arrowhead”, and Delta Sagittarii is called Kaus Media, the “center of the bow,” from which the arrow protrudes. Kaus Media bisects Lambda Sagittarii (λ Sgr) andEpsilon Sagittarii (ε Sgr), whose names Kaus Borealis and Kaus Australis refer to the northern and southern portions of the bow, respectively.
Massive Star – The Main Important One for us anyway!
The Sun does not have enough mass to explode as a supernova. Instead it will exit the main sequence in approximately 5.4 billion years and start to turn into a red giant. It is
calculated that the Sun will become sufficiently large to engulf the current orbits of the solar system‘s inner planets, possibly including Earth.
Even before it becomes a red giant, the luminosity of the Sun will have nearly doubled, and the Earth will be hotter than Venus is today. Once the core hydrogen is exhausted in 5.4 billion years, the Sun will expand into a subgiant phase and slowly double in size over about half a billion years.
It will then expand more rapidly over about half a billion years until it is over two hundred times larger than today and a couple of thousand times more luminous. This then starts the red giant branch (RGB) phase where the Sun will spend around a billion years and lose around a third of its mass.
After RGB the Sun now has only about 120 million years of active life left, but they are highly eventful. First the core ignites violently in the helium flash, and the Sun shrinks back to around 10 times its current size with 50 times the luminosity, with a temperature a little lower than today.
It has now reached the red clump or horizontal branch (HB), but a star of the Sun’s mass does not evolve blueward along the HB. Instead it just becomes mildly larger and more luminous over about 100 million years as it continues to burn helium in the core.
Our Star Is Massive
Explore for Galaxies Galore
The Virgo Cluster (VC) is a cluster of galaxies whose center is 53.8 ± 0.3 Mly (16.5 ± 0.1 Mpc) away in the constellation Virgo. Comprising approximately 1300 (and possibly up to 2000) member galaxies, the cluster forms the heart of the larger Virgo Supercluster, of which the Local Group (LG) is an outlying member. However, the LG experiences the mass of the VC as the Virgocentric flow. It is estimated that the VC’s mass is 1.2×1015 M☉ out to 8 degrees of the cluster’s center or a radius of about 2.2 Mpc.
Many of the brighter galaxies in this cluster, including the giant elliptical galaxy Messier 87, were discovered in the late 1770s and early 1780s and subsequently included in Charles Messier‘s catalogue of non-cometary fuzzy objects. Described by Messier as nebulae without stars, their true nature was not recognized until the 1920s.
The cluster subtends a maximum arc of approximately 8 degrees centered in the constellation Virgo. Many of the member galaxies of the cluster are visible with a small telescope. Its brightest member is the elliptical galaxy Messier 49; however its most famous member is the also elliptical galaxy Messier 87, that unlike the former is located in the center of the cluster.
In physics and optics, the Fraunhofer lines are a set of spectral lines named after the German physicist Joseph von Fraunhofer (1787–1826) . The lines were originally observed as dark features (absorption lines) in the optical spectrum of the Sun.
The Fraunhofer lines are typical spectral absorption lines. These dark lines are produced whenever a cold gas is between a broad spectrum photon source and the detector. In this case, a decrease in the intensity of light in the frequency of the incident photon is seen as the photons are absorbed, then re-emitted in random directions, which are mostly in directions different from the original one.
This results in an absorption line, since the narrow frequency band of light initially traveling toward the detector, has been turned into heat or re-emitted in other directions.
By contrast, if the detector sees photons emitted directly from a glowing gas, then the detector often sees photons emitted in a narrow frequency range by quantum emission processes in atoms in the hot gas, resulting in an emission line. In the Sun, Fraunhofer lines are seen from gas in the outer regions of the Sun, which are too cold to directly produce emission lines of the elements they represent.
Naked Eye Sky Viewing
The chemical in the eye needed is called rhodopsin..
Rhodopsin, also known as visual purple, due to its pinkish color, and ὄψις (ópsis, “sight”), is a light-sensitive receptor protein. It is a biological pigment in photoreceptor cells of the retina. Rhodopsin is the primary pigment found in rod photoreceptors. Rhodopsins belong to the G-protein-coupled receptor(GPCR) family. They are extremely sensitive to light, enabling vision in low-light conditions. Exposed to light, the pigment immediately photobleaches, and it takes about 45 minutes to regenerate fully in humans.
In astronomy and navigation, the celestial sphere is an imaginary sphere of arbitrarily large radius, concentric with a particular celestial body. All objects in the observer’s sky can be thought of as projected upon the inside surface of the celestial sphere, as if it were the underside of a dome or a hemispherical screen. The celestial sphere is a practical tool for spherical astronomy, allowing observers to plot positions of objects in the sky when their distances are unknown or unimportant.
Because astronomical objects are at such remote distances, casual observation of the sky offers no information on the actual distances. All objects seem equally far away, as if fixed to the inside of a sphere of large but unknown radius, which rotates from east to west overhead while underfoot, the celestial body seems to stand still. For purposes of spherical astronomy, which is concerned only with the directions to objects, it makes no difference whether this is actually the case, or if it is the celestial body which rotates while the celestial sphere stands still.
The celestial sphere can be considered to be infinite in radius. This means any point within it, including that occupied by the observer, can be considered the center. It also means that all parallel lines, be they millimetres apart or across the Solar System from each other, will seem to intersect the sphere at a single point, analogous to the vanishing point of graphical perspective. All parallel planes will seem to intersect the sphere in a coincident great circle (a “vanishing circle”). Conversely, observers looking toward the same point on an infinite-radius celestial sphere will be looking along parallel lines, and observers looking toward the same great circle, along parallel planes. On an infinite-radius celestial sphere, all observers see the same things in the same direction.
For some objects, this is over-simplified. Objects which are relatively near to the observer (for instance, the Moon) will seem to change position against the distant celestial sphere if the observer moves far enough, say, from one side of the celestial body to the other. This effect, known as parallax, can be represented as a small offset from a mean position. The celestial sphere can be considered to be centered at the celestial body’s center, A star’s center, or any other convenient location, and offsets from positions referred to these centers can be calculated. In this way, astronomers can predict geocentric or heliocentric positions of objects on the celestial sphere, without the need to calculate the individual geometry of any particular observer, and the utility of the celestial sphere is maintained. Individual observers can work out their own small offsets from the mean positions, if necessary. In many cases in astronomy, the offsets are insignificant.
The celestial sphere can be thus be thought of as a kind of astronomical shorthand, and is applied very frequently by astronomers. For instance, the Astronomical Almanac for 2010 lists the apparent geocentric position of Earth’s Moon, 1 Jan 2010 at 0h Terrestrial Time, in equatorial coordinates, as right ascension 6h 57m 48s.86, declination +23° 30′ 05″.5. Implied in this position is that it is as projected onto the celestial sphere; any observer at any location looking in that direction would see the “geocentric Moon” in the same place against the stars. For many rough uses (for instance, calculating an approximate phase of the Moon), this position, as seen from the Earth’s center, is adequate. For applications requiring precision (for instance, calculating the shadow path of an eclipse), the Almanac gives formulae and methods for calculating the topocentric coordinates, that is, as seen from a particular place on the Earth’s surface, based on the geocentric position. This greatly abbreviates the amount of detail necessary in such almanacs, as each observer can handle their own specific circumstances.
Celestial coordinate systems
These concepts are important for understanding celestial reference systems, the methods in which the positions of objects in the sky are measured. Certain reference lines and planes on the celestial body, when projected onto the celestial sphere, form the bases of the reference systems. These include the celestial equator, axis, and the orbit. At their intersections with the celestial sphere, these form the celestial equator, the north and south celestial poles and the ecliptic, respectively. As the celestial sphere is considered infinite in radius, all observers see the celestial equator, celestial poles and ecliptic at the same place against the background stars.
Directions toward objects in the sky can be quantified by constructing, from these bases, celestial coordinate systems. Similar to the terrestrial longitude and latitude, the equatorial system of right ascension and declination specifies positions relative to the celestial equator and celestial poles. The ecliptic system of celestial longitude and celestial latitude specifies positions relative to the celestial body’s orbit. There are more coordinate systems besides the equatorial right ascension/declination system and the ecliptic system.
The ancients assumed the literal truth of stars attached to the celestial sphere of Earth, revolving about the Earth in one day, and a fixed Earth. The Eudoxan planetary model, on which the Aristotelian and Ptolemaic models were based, was the first geometric explanation for the “wandering” of the classical planets. The outer most of these “crystal spheres” was thought to carry the fixed stars. Eudoxus used 27 concentric spherical solids to answer Plato’s challenge: “By the assumption of what uniform and orderly motions can the apparent motions of the planets be accounted for?”
THE FIRST TO PHOTOGRAPH NEBULA
HIS Life and work
Henry Draper’s father, John William Draper, was an accomplished doctor, chemist, botanist, and professor at New York University; he was also the first to photograph the moon through a telescope in the winter of 1839–1840. Draper’s mother was Antonia Coetana de Paiva Pereira Gardner, daughter of the personal physician to the Emperor of Brazil. His niece, Antonia Maury was also an astronomer.
He graduated from New York University School of Medicine, at the age of 20, in 1857. He worked first as a physician at Bellevue Hospital, and later as both a professor and dean of medicine at New York University (NYU). In 1867 he married Mary Anna Palmer, a wealthy socialite.
Draper was one of the pioneers of the use of astrophotography. In 1872, he took a stellar spectrum that showed absorption lines, others, such as Joseph Fraunhofer, Lewis Morris Rutherfurd and Angelo Secchi, preceded him in that ambition.
He resigned his chair in the medical department in 1873, to allow for more time for original research.
He directed an expedition to photograph the 1874 transit of Venus, and was the first to photograph the Orion Nebula, on September 30, 1880. Using his 11 inch Clark Brothers photographic refractor he took a 50 minute exposure. He photographed the spectrum of Jupiter in 1880.
Draper’s observatory, where he took his much-admired photographs of the moon, was located in Hastings-on-Hudson, New York, and today the building functions as the Hastings-on-Hudson Historical Society.
Draper received numerous awards, including honorary LL.D. law degrees from NYU and the University of Wisconsin–Madison in 1882, a Congressional medal for directing the U.S. expedition to photograph the 1874 transit of Venus, and election to both the National Academy of Sciences and the Astronomische Gesellschaft.
In addition, he held memberships in the American Photographic Society, the American Philosophical Society, the American Academy of Arts and Sciences, and the American Association for the Advancement of Science.
After his untimely early death from double pleurisy, his widow funded the Henry Draper Medal for outstanding contributions to astrophysics and a telescope, which was used to prepare the Henry Draper Catalog of stellar spectra.
Wondered why Galaxies and Nebulae have an NGC number preceding them?
…Then you should get to know astronomer John Dreyer
His major contribution was the monumental New General Catalogue of Nebulae and Clusters of Stars (based on William Herschels Catalogue of Nebulae), the catalogue numbers of which are still in use, as well as two supplementary Index Catalogues.
Dreyer was also an historian of astronomy. In 1890 he published a biography of Tycho Brahe, a noted astronomer from his native country, and in his later years he edited Tycho’s publications and unpublished correspondence. History of the Planetary Systems from Thales to Kepler (1905), his survey of the history of astronomy, while dated in some respects, is still a good introduction to the subject. It is currently printed with the title A History of Astronomy from Thales to Kepler.
He was born Johan Ludvig Emil Dreyer in Copenhagen: his father, Lieutenant General John Christopher Dreyer, was the Danish Minister for War and the Navy. When he was 14 he became interested in astronomy and regularly visited Hans Schjellerup at the Copenhagen observatory. He was educated in Copenhagen but in 1874, at the age of 22, he went to Parsonstown, Ireland. There he worked as the assistant of Lord Rosse (the son and successor of the Lord Rosse who built the Leviathan of Parsonstown telescope).
During 1878 he moved to Dunsink, the site of the Trinity College Observatory of Dublin University to work for Robert Stawell Ball. In 1882 he relocated again, this time to Armagh Observatory, where he served as Director until his retirement in 1916. In 1885 he became a British citizen. In 1916 he and his wife Kate moved to Oxford where Dreyer worked on his 15 volume edition of the works of Tycho Brahe, the last volume of which was published after his death.
He won the Gold Medal of the Royal Astronomical Society in 1916 and served as the society’s president from 1923 until 1925. He died on September 14, 1926 in Oxford.
Messier 82 (also known as NGC 3034, Cigar Galaxy or M82) is a starburst galaxy about 12 million light-years away in the constellation Ursa Major. It is about five times more luminous than the whole Milky Way and one hundred times more luminous than our galaxy’s center.
The starburst activity is thought to be triggered by interaction with neighboring galaxy M81, and M82 is a member of the M81 Group. As the closest starburst galaxy to our own, M82 is the prototypical example of this type of galaxy. SN 2014J, a Type Ia supernova, was observed in the galaxy on 21 January 2014. In 2014, in studying M82, scientists discovered the brightest pulsar yet known, designated M82 X-2.
M82 was previously believed to be an irregular galaxy. In 2005, however, two symmetric spiral arms were discovered in near-infrared (NIR) images of M82. The arms were detected by subtracting an axisymmetric exponential disk from the NIR images. Even though the arms were detected in NIR images, they are bluer than the disk. The arms were previously missed due to M82’s high disk surface brightness, our nearly edge-on view of this galaxy (~80°), and confusion by a complex network of dusty filaments in its optical images. These arms emanate from the ends of the NIR bar and can be followed for the length of 3 disc scales. Assuming that the northern part of M82 is nearer to us, as most of the literature does, the observed sense of rotation implies trailing arms.
In 2005, the Hubble Space Telescope revealed 197 young massive clusters in the starburst core. The average mass of these clusters is around 200,000 solar masses, hence the starburst core is a very energetic and high-density environment. Throughout the galaxy’s center, young stars are being born 10 times faster than they are inside our entire Milky Way Galaxy.
In the core of M82, the active starburst region spans a diameter of 500 pc. Four high surface brightness regions or clumps (designated A, C, D, and E) are detectable in this region at visible wavelengths. These clumps correspond to known sources at X-ray, infrared, and radio frequencies. Consequently, they are thought to be the least obscured starburst clusters from our vantage point. M82’s unique bipolar outflow (or ‘superwind‘) appears to be concentrated on clumps A and C and is fueled by energy released by supernovae within the clumps which occur at a rate of about one every ten years.
The Chandra X-ray Observatory detected fluctuating X-ray emissions from a location approximately 600 light-years away from the center of M82. Astronomers have postulated that this fluctuating emission comes from the first known intermediate-mass black hole, of roughly 200 to 5000 solar masses. M82, like most galaxies, hosts a supermassive black hole at its center with a mass of approximately 3 x 107 solar masses as measured from stellar dynamics.
In April 2010, radio astronomers working at the Jodrell Bank Observatory of the University of Manchester reported an unknown object in M82. The object started sending out radio waves, and the emission did not look like anything seen anywhere in the universe before. There have been several theories about the nature of this unknown object, but currently no theory entirely fits the observed data. It has been suggested that the object could be an unusual “micro quasar”, having very high radio luminosity yet low X-ray luminosity, and being fairly stable, it could be an analogue of the low X-ray luminosity galactic microquasar SS 433.
However, all known microquasars produce large quantities of X-rays, whereas the object’s X-ray flux is below the measurement threshold. The object is located at several arcseconds from the center of M82 which makes it unlikely to be associated with a supermassive black hole. It has an apparent superluminal motion of four times the speed of light relative to the galaxy center. Apparent superluminal motion is consistent with relativistic jets in massive black holes and does not indicate that the source itself is moving above lightspeed.
Messier 81 triggering starburst
Forming a striking pair in small telescopes with nearby spiral M81, M82 is being physically affected by its larger neighbor. Tidal forces caused by gravity have deformed this galaxy, a process that started about 100 million years ago. This interaction has caused star formation to increase tenfold compared to “normal” galaxies.
Recently, M82 has undergone at least one tidal encounter with M81 resulting in a large amount of gas being funneled into the galaxy’s core over the last 200 Myr. The most recent such encounter is thought to have happened around 2–5×108 years ago and resulted in a concentrated starburst together with a corresponding marked peak in the cluster age distribution. This starburst ran for up to ~50 Myr at a rate of ~10 M⊙ per year. Two subsequent starbursts followed, the last (~4–6 Myr ago) of which may have formed the core clusters, both super star clusters (SSCs) and their lighter counterparts.
Oddly enough, stars in M82’s disk seem to have been formed in a burst 500 million years ago, leaving its disk littered with hundreds of clusters with properties similar to globular clusters (but younger), and stopped 100 million years ago with no star formation taking place in this galaxy outside the central starburst and, at low levels since 1 billion years ago, on its halo. A suggestion to explain those features is that M82 was previously a low surface brightness galaxy where star formation was triggered due to interactions with its giant neighbor.
Ignoring any difference in their respective distances from us, the centers of M81 and M82 are visually separated by about 130,000 light-years. The actual separation is 300+300
On 21 January 2014 at 19.20 UT a previously unseen star was observed in M82 at magnitude +11.7 by Dr. Steve J. Fossey, along with a team of 4 of his students, at UCL’s training observatory, the University of London Observatory. It had brightened to magnitude +10.9 by 23 January. Examination of earlier observations of M82 found the supernova to be present on 15, 16, 17, 19, 20 and 22 January, brightening from magnitude +14.4 to +11.3; there was no sign of it, to limiting magnitude +17, on 14 January.
It was suggested that it could become as bright as magnitude +8.5, well within the visual range of small telescopes and large binoculars. Preliminary analysis classified it as “a young, reddened Type Ia supernova“. The International Astronomical Union (IAU) has designated it SN 2014J. This is one of the closest supernovae to Earth observed in recent decades. SN 1993J was at a very similar distance, in M82’s larger companion galaxy M81, and SN 1987A was much closer. It is the closest Type Ia since SN 1972E.
Fried Egg Galaxy NGC 7742
The galaxy is unusual in that it contains a ring but no bar. Typically, bars are needed to produce a ring structure. The bars’ gravitational forces move gas to the ends of the bars, where it forms into the rings seen in many barred spiral galaxies. In this galaxy, however, no bar is present, so this mechanism cannot be used to explain the formation of the ring. O. K. Sil’chenko and A. V. Moiseev proposed that the ring was formed partly as the result of a merger event in which a smaller gas-rich dwarf galaxy collided with NGC 7742.
As evidence for this, they point to the unusually bright central region, the presence of highly inclined central gas disk, and the presence of gas that is counterrotating (or rotating in the opposite direction) with respect to the stars.
Neptune was the first and only planet found by mathematical prediction rather than by empirical observation. Unexpected changes in the orbit of Uranus led Alexis Bouvard to deduce that its orbit was subject to gravitational perturbation by an unknown planet.
Neptune was subsequently observed on 23 September 1846 by Johann Galle within a degree of the position predicted by Urbain Le Verrier, and its largest moon, Triton, was discovered shortly thereafter, though none of the planet’s remaining 13 moons were located telescopically until the 20th century.
Neptune was visited by Voyager 2, when it flew by the planet on 25 August 1989.
Neptune is similar in composition to Uranus, and both have compositions that differ from those of the larger gas giants, Jupiter and Saturn. Neptune’s atmosphere, like Jupiter’s and Saturn’s, is composed primarily of hydrogen and helium, along with traces of hydrocarbons and possibly nitrogen; it contains a higher proportion of “ices” such as water, ammonia, and methane. Astronomers sometimes categorise Uranus and Neptune as “ice giants” to emphasise this distinction. The interior of Neptune, like that of Uranus, is primarily composed of ices and rock. Perhaps the core has a solid surface, but the temperature would be thousands of degrees and the atmospheric pressure crushing. Traces of methane in the outermost regions in part account for the planet’s blue appearance.
In contrast to the hazy, relatively featureless atmosphere of Uranus, Neptune’s atmosphere has active and visible weather patterns. For example, at the time of the 1989 Voyager 2 flyby, the planet’s southern hemisphere had a Great Dark Spot comparable to the Great Red Spot on Jupiter. These weather patterns are driven by the strongest sustained winds of any planet in the Solar System, with recorded wind speeds as high as 2,100 kilometres per hour (1,300 mph). Because of its great distance from the Sun, Neptune’s outer atmosphere is one of the coldest places in the Solar System, with temperatures at its cloud tops approaching 55 K (-218 °C). Temperatures at the planet’s centre are approximately 5,400 K (5,100 °C). Neptune has a faint and fragmented ring system (labelled “arcs”), which may have been detected during the 1960s but was indisputably confirmed only in 1989 by Voyager 2.
Neptune is the eighth and farthest planet from the Sun in the Solar System. It is the fourth-largest planet by diameter and the third-largest by mass. Among the gaseous planets in the Solar System, Neptune is the most dense. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times the mass of Earth, and not as dense as Neptune. Neptune orbits the Sun at an average distance of 30.1 astronomical units. Named after the Roman god of the sea.
Neptune Quick Facts
- Neptune orbits our sun, a star. Neptune is the eighth planet from the sun at a distance of about 4.5 billion km (2.8 billion miles) or 30.07 AU.
- One day on Neptune takes about 16 hours (the time it takes for Neptune to rotate or spin once). Neptune makes a complete orbit around the sun (a year in Neptunian time) in about 165 Earth years (60,190 Earth days).
- Neptune is a sister ice giant to Uranus. Neptune is mostly made of a very thick, very hot combination of water (H2O), ammonia (NH3), and methane (CH4) over a possible heavier, approximately Earth-sized, solid core.
- Neptune’s atmosphere is made up mostly of hydrogen (H2), helium (He) and methane (CH4).
- Neptune has 13 confirmed moons (and 1 more awaiting official confirmation of discovery). Neptune’s moons are named after various sea gods and nymphs in Greek mythology.
- Neptune has six rings.
- Voyager 2 is the only spacecraft to have visited Neptune.
- Neptune cannot support life as we know it.
- At times during the course of Neptune’s orbit, dwarf planet Pluto is actually closer to the sun, and us, than Neptune. This is due to the unusual elliptical (egg) shape of Pluto’s orbit.
July 2016 – Arrival Month?
If you are as fascinated by the planet Jupiter as much as me, make a note of that date! To keep up with latest about Juno, bookmark this Juno News link.
It’s visible with the naked eye at the moment (march) though it is quite a faint one.
Serpens is a constellation of the northern hemisphere. One of the 48
constellations listed by the 2nd century astronomer Ptolemy, it
remains one of the 88 modern constellations defined by the International Astronomical
Union. It is unique among the modern constellations in being split
into two non-contiguous parts, Serpens
Head) to the west and Serpens
Tail) to the east. Between these two halves lies the constellation of Ophiuchus, the
“Serpent-Bearer”. In figurative representations, the body of the
serpent is represented as passing behind Ophiuchus between μ Ser in Serpens Caput and ν Ser in Serpens
The brightest star in Serpens is Unukalhai or Cor
Heart”, with an apparent magnitude of 2.63. Part of the Milky
through Serpens Cauda, which is therefore rich in deep-sky
objects, such as the Eagle
4703) and its associated star cluster Messier
16. The nebula measures 70 light-years by 50 light-years and
contains the Pillars of Creation, three dust clouds that became
famous for the image taken by the Hubble Space Telescope. Located in Serpens Caput are Seyfert’s Sextet, one of the densest galaxy
clusters known, and Arp 220, the
infrared galaxy. In addition, it also contains the Hercules–Corona Borealis Great
Wall, the largest object in the universe.
Keep track at the Heavens Above astronomy site.
Partial solar eclipses are hazardous to view because the eye’s pupil is not adapted to the unusually high visual contrast: the pupil dilates according to the total amount of light in the field of view, not by the brightest object in the field. During partial eclipses most sunlight is blocked by the Moon passing in front of the Sun, but the uncovered parts of the photosphere have the same surface brightness as during a normal day.
We won’t know if it did
Milky Way Has 4 Billion Years to Live
Four billion years from now, our galaxy, the Milky Way, will collide with our large spiraled neighbor, Andromeda.
The galaxies as we know them will not survive.
In fact, our solar system is going to outlive our galaxy. At that point, the sun will not yet be a red giant star – but it will have grown bright enough to roast Earth’s surface. Any life
forms still there, though, will be treated to some pretty spectacular cosmic choreography.
Currently, Andromeda and the Milky Way are about 2.5 million light-years apart. Fueled by gravity, the two galaxies are hurtling toward one another at 402,000 kilometers per hour.
But even at that speed, they won’t meet for another four billion years. Then, the two galaxies will collide head-on and fly through one another, leaving gassy, starry tendrils in their
wakes. For eons, the pair will continue to come together and fly apart, scrambling stars and redrawing constellations until eventually, after a billion or so years have passed, the two
Then, the solar system will have a new cosmic address: A giant elliptical galaxy, formed by the collision and merger of the Milky Way and Andromeda.
Gravitational collapse is the inward fall of an astronomical object due to the influence of its own gravity which tends to draw the object toward its center of mass. In any stable body, this gravitational force is counterbalanced by the internal pressure of the body acting in the opposite direction. If the gravitational force is stronger than the forces acting outward, the equilibrium becomes unstable and a collapse occurs until the internal pressure increases sufficiently that equilibrium is once again attained (the exception being a black hole).
Because gravity is weak compared to other fundamental forces, gravitational collapse is usually associated with very massive bodies or collections of bodies, such as stars (including collapsed stars such as supernovae, neutron stars and black holes) and massive collections of stars such as globular clusters and galaxies.
Gravitational collapse is at the heart of structure formation in the universe. An initial smooth distribution of matter will eventually collapse and cause a hierarchy of structures, such as clusters of galaxies, stellar groups, stars and planets. For example, a star is born through the gradual gravitational collapse of a cloud of interstellar matter. The compression caused by the collapse raises the temperature until nuclear fuel ignites in the center of the star and the collapse comes to a halt. The thermal pressure gradient (acting outward) balances the gravity (acting inward) and the star is in dynamic equilibrium between the two forces.
Gravitational collapse of a star occurs at the end of its lifetime, also called the death of the star. When all stellar energy sources are exhausted, the star will undergo a gravitational collapse. In this sense a star is in a “temporary” equilibrium state between a gravitational collapse at stellar birth and a further gravitational collapse at stellar death. The end state is called a compact star or stellar remnants.
The types of compact stars are:
- White dwarfs, in which gravity is opposed byelectron degeneracy pressure;
- Neutron stars, in which gravity is opposed byneutron degeneracy pressure and short-range repulsive neutron–neutron interactions mediated by the strong force;
- Black holes, in which the physics at the center is unknown.
The collapse to a white dwarf takes place over tens of thousands of years, while the star blows off its outer envelope to form a planetary nebula. If it has a companion star, a white dwarf-sized object can accrete matter from the companion star until it reaches the Chandrasekhar limit, at which point gravitational collapse takes over again. While it might seem that the white dwarf might collapse to the next stage (neutron star), they instead undergo runaway carbon fusion, blowing completely apart in a Type Ia supernova. Neutron stars are formed by gravitational collapse of larger stars, the remnant of other types of supernova.
Even more gigantic stars, above the Tolman–Oppenheimer–Volkoff limit cannot find a new dynamical equilibrium with any known force opposing gravity. Hence, the collapse continues with nothing to stop it. Once it collapses to within its Schwarzschild radius, not even light can escape from the star, therefore it becomes a black hole. According to theories, at some point later, the collapsing object will reach the maximum possible energy density for a certain volume of space or the Planck density (as there is nothing that can stop it). This is when the known laws of gravity cease to be valid. There are competing theories as to what occurs at this point, but it can no longer really be considered gravitational collapse at that stage.
It might be thought that a sufficiently large neutron star could exist inside its Schwarzschild radius and appear like a black hole without having all the mass compressed to a singularity at the center; however, this is a misconception .Within the event horizon, matter would have to move outward faster than the speed of light in order to remain stable and avoid collapsing to the center. No physical force therefore can prevent the star from collapsing to a singularity (at least within the currently understood framework of general relativity; this doesn’t hold for the Einstein–Yang–Mills–Dirac system). A model for nonspherical collapse in general relativity with emission of matter and gravitational waves has been presented.
Eukaryote (Eucaryotic cells)
membranes. Eukaryotes belong to the taxon Eukarya or
Eukaryota. The defining membrane-bound structure
that sets eukaryotic cells apart from prokaryotic
cells (Bacteria and Archaea) is the
nucleus, which contains the
Golgi apparatus. In
addition, plants and algae contain
in eukaryotes differs from that in prokaryotes.
There are two types of division processes. In mitosis, one
cell divides to produce two genetically identical cells. In meiosis, which
is required in sexual
reproduction, one diploid cell
(having two instances of each chromosome, one from each parent)
undergoes recombination of each pair of parental chromosomes, and
then two stages of cell division, resulting in four haploid cells (gametes). Each
gamete has just one complement of
chromosomes, each a unique mix of the corresponding pair of parental
The domain Eukaryota appears to be monophyletic, and so makes up one of the
three domains of
life. The two other domains, Bacteria and Archaea, are prokaryotes and have none of the above features.
represent a tiny minority of all living things; even in a human body
10 times more microbes than human cells. However, due to their much
size, their collective worldwide biomass is estimated at about equal to
prokaryotes. Eukaryotes first developed approximately 1.6–2.1 billion
The Very Bright Procyon
Procyon is the brightest star in the constellation Canis Minor.
To the naked eye, it appears to be a single star, the eighth brightest
in the night sky with a visual apparent magnitude of 0.34.It is
classified as a binary star system, consisting of a white main-sequence
star of spectral type F5 IV–V, named Procyon A, and a faint white dwarf
companion of spectral type DQZ, named Procyon B. The reason for its
brightness is not its intrinsic luminosity but its relative closeness
to the Sun; as determined by the European Space Agency Hipparcos
astrometry satellite, it lies at a distance of just 11.46 light-years
(3.51 parsecs),and is therefore one of our nearest stellar neighbours.
Its closest neighboring star is Luyten’s Star, about 1.12 ly (0.34 pc)
away, and the latter would appear as a visual magnitude 2.7 star in the
night sky of a hypothetical planet orbiting Procyon.
Procyon is the eighth brightest star in the night sky, culminating at midnight on January 14.It forms one of the three vertices of the Winter Triangle asterism, in combination with Sirius and Betelgeuse.
period for evening viewing of Procyon is in late winter. It has a color
index is 0.42, and its hue has been described as having a faint yellow
tinge to it.
Procyon is a binary star system with a bright primary component,
Procyon A, having an apparent magnitude of 0.34, and a faint companion,
Procyon B, at magnitude 10.7. The primary has a stellar classification
of F5IV–V, indicating that it is a late-stage F-type main-sequence
star. The effective surface temperature of the star is an estimated
6,530 K, giving it a white hue. It is 1.4 times the solar mass , twice the solar
radius, and has 6.9 times the Sun’s luminosity . Procyon A is bright
for its spectral class, suggesting that it is a subgiant that has nearly fused its core hydrogen into helium, after which it will expand as “burning” moves outside the core. As it
continues to expand, the star will eventually swell to about 80 to 150
times its current diameter and become a red or orange color. This will
probably happen within 10 to 100 million years.
Like Sirius B, Procyon’s companion is a white dwarf that was inferred
from astrometric data long before it was observed. Its existence had
been postulated by Friedrich Bessel as early as 1844, and, although its
orbital elements had been calculated by Arthur Auwers in 1862 as part
of his thesis, Procyon B was not visually confirmed until 1896 when
John Martin Schaeberle observed it at the predicted position using the
36-inch refractor at Lick Observatory. It is more difficult to observe
from Earth than Sirius B, due to a greater apparent magnitude
difference and smaller angular separation from its primary. The average
separation of the two components is 15.0 AUs, a little less than the
distance between Uranus and the Sun, though the eccentric orbit carries
them as close as 8.9 AUs and as far as 21.0 AU.
At 0.6 M?, Procyon B is considerably less massive than Sirius B;
however, the peculiarities of degenerate matter ensure that it is
larger than its more famous neighbor, with an estimated radius of 8,600
km, versus 5,800 km for Sirius B. With a surface temperature of 7,740
K, it is also much cooler than Sirius B; this is a testament to its
lesser mass and greater age. The mass of the progenitor star for
Procyon B was about 2.5 M? and it came to the end of its life some 1.7
± 0.1 Gyr ago, after a main-sequence lifetime of 400–600 Myr. For this
reason, the age of Procyon A is expected to be at least 2 Gyr.
Get more information at EarthSky
The most massive galaxies in the sky are giant elliptical galaxies. Their stars are on orbits that are randomly oriented within the galaxy (i.e. they are not rotating like disk galaxies). They are composed of old stars and have little to no dust. All elliptical galaxies probed so far have supermassive black holes in their center, and the mass of these black holes is correlated with the mass of the elliptical galaxy. They are also correlated to a property called sigma which is the speed of the stars at the far edge of the elliptical galaxies. Elliptical galaxies do not have disks around them, although some bulges of disk galaxies look similar to elliptical galaxies. One is more likely to find elliptical galaxies in more crowded regions of the universe (such as galaxy clusters).
Astronomers now see elliptical galaxies as some of the most evolved systems in the universe. It is widely accepted that the main driving force for the evolution of elliptical galaxies is mergers of smaller galaxies. These mergers can be extremely violent; galaxies often collide at speeds of 500 kilometers per second.
Many galaxies in the universe are gravitationally bound to other galaxies, that is to say they will never escape the pull of the other galaxy. If the galaxies are of similar size, the resultant galaxy will appear similar to neither of the two galaxies merging, but would instead be an elliptical galaxy. An image of an ongoing merger of equal sized disk galaxies is shown left.
In the Local Group, the Milky Way and M31 (the Andromeda Galaxy) are gravitationally bound, and currently approaching each other at high speed. If the two galaxies do meet they will pass through each other, with gravity distorting both galaxies severely and ejecting some gas, dust and stars into intergalactic space. They will travel apart, slow down, and then again be drawn towards each other, and again collide.
Eventually both galaxies will have merged completely, streams of gas and dust will be flying through the space near the newly formed giant elliptical galaxy. M31 is actually already distorted: the edges are warped. This is probably because of interactions with its own galactic companions, as well as possible mergers with dwarf spheroidal galaxies in the recent past – the remnants of which are still visible in the disk populations.
While scientists have learned a great deal about ours and other galaxies, the most fundamental questions about formation and evolution remain only tentatively answered.
Hinode… formerly Solar-B, is a Japan Aerospace Exploration Agency Solar mission with United States and United Kingdom collaboration. It is the follow-up to the Yohkoh(Solar-A) mission and it was launched on the final flight of the M-V-7 rocket from Uchinoura Space Center, Japan on 22 September 2006 at 21:36 UTC (23 September, 06:36 JST).
Initial orbit was perigee height 280 km, apogee height 686 km, inclination 98.3 degrees. Then the satellite maneuvered to the quasi-circular sun-synchronous orbit over the day/night terminator, which allows near-continuous observation of the Sun. On 28 October 2006, the probe’s instruments captured their first images.
The data from Hinode are being downloaded to the Norwegian, terrestrial Svalsat station, operated by Kongsberg a few kilometres west of Longyearbyen, Svalbard. From there, data are transmitted by Telenors through a fibre-optic network to mainland Norway at Harstad, and on to data users in North America, Europe and Japan.
The Scattered Disc
A sparsely populated region, overlapping with the Kuiper belt but extending as far as 100 AU and farther. Scattered disc objects (SDOs) travel in highly elliptical orbits, usually also highly inclined to the ecliptic. Most models of Solar System formation show both KBOs and SDOs first forming in a primordial comet belt, whereas later gravitational interactions, particularly with Neptune, sent the objects spiraling outward, some into stable orbits (the KBOs) and some into unstable orbits, becoming the scattered disc. Due to its unstable nature, the scattered disc is believed to be the point of origin for many of the Solar System’s short-period comets. Their dynamic orbits occasionally force them into the inner Solar System, becoming first centaurs, and then short-period comets.
According to the Minor Planet Center, which officially catalogues all trans-Neptunian objects, a KBO, strictly speaking, is any object that orbits exclusively within the defined Kuiper belt region regardless of origin or composition. Objects found outside the belt are classed as scattered objects. However, in some scientific circles the term “Kuiper belt object” has become synonymous with any icy minor planet native to the outer Solar System believed to have been part of that initial class, even if its orbit during the bulk of Solar System history has been beyond the Kuiper belt (e.g. in the scattered-disc region). They often describe scattered disc objects as “scattered Kuiper belt objects”. Eris, which is known to be more massive than Pluto, is often referred to as a KBO, but is technically an SDO. A consensus among astronomers as to the precise definition of the Kuiper belt has yet to be reached, and this issue remains unresolved.
The centaurs, which are not normally considered part of the Kuiper belt, are also believed to be scattered objects, the only difference being that they were scattered inward, rather than outward. The Minor Planet Center groups the centaurs and the SDOs together as scattered objects.
Outer Region of The Solar System
The Kuiper belt – sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but it is far larger—20 times as wide and 20 to 200 times as massive. Like the asteroid belt, it consists mainly of small bodies, or remnants from the Solar System’s formation. Although most asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles (termed “ices”), such as methane, ammonia and water. The Kuiper belt is home to at least three dwarf planets: Pluto, Haumea, and Makemake. Some of the Solar System’s moons, such as Neptune’s Triton and Saturn‘s Phoebe, are also believed to have originated in the region.
The Kuiper belt was named after Dutch-American astronomer Gerard Kuiper, though his role in hypothesising it has been heavily contested. Since it was discovered in 1992, the number of known Kuiper belt objects (KBOs) has increased to over a thousand, and more than 100,000 KBOs over 100 km (62 mi) in diameter are believed to exist. The Kuiper belt was initially thought to be the main repository for periodic comets, those with orbits lasting less than 200 years. However, studies since the mid-1990s have shown that the belt is dynamically stable, and that comets’ true place of origin is the scattered disc, a dynamically active zone created by the outward motion of Neptune 4.5 billion years ago; scattered disc objects such as Eris have extremely eccentric orbits that take them as far as 100 AU from the Sun.
The Kuiper belt should not be confused with the hypothesized Oort cloud, which is a thousand times more distant. The objects within the Kuiper belt, together with the members of the scattered disc and any potential Hills cloud or Oort cloud objects, are collectively referred to as trans-Neptunian objects (TNOs).
Pluto is the largest member of the Kuiper belt, and the second largest known TNO, the largest being Eris in the scattered disc. Originally considered a planet, Pluto’s status as part of the Kuiper belt caused it to be reclassified as a “dwarf planet” in 2006. It is compositionally similar to many other objects of the Kuiper belt, and its orbital period is characteristic of a class of KBOs, known as “plutinos“, that share the same 2:3 resonance with Neptune.
After the discovery of Pluto in 1930, many speculated that it might not be alone. The region now called the Kuiper belt was hypothesized in various forms for decades. It was only in 1992 that the first direct evidence for its existence was found. The number and variety of prior speculations on the nature of the Kuiper belt have led to continued uncertainty as to who deserves credit for first proposing it.
About Mr Kuiper Himself
Kuiper, the son of a tailor in the village of Harenkarspel in North Holland, had an early interest in astronomy. He had extraordinarily sharp eyesight, allowing him to see magnitude 7.5 stars with the naked eye, about four times fainter than visible to normal eyes. He went to study at Leiden University in 1924, where at the time a very large number of astronomers had congregated.
He befriended fellow students Bart Bok and Pieter Oosterhoff and was taught by Ejnar Hertzsprung, Antonie Pannekoek, Willem de Sitter, Jan Woltjer, Jan Oort and the physicist Paul Ehrenfest. He received his B.Sc. in Astronomy in 1927 and continued straight on with his graduate studies.
Kuiper finished his doctoral thesis on binary stars with Hertzsprung in 1933, after which he traveled to California to become a fellow under Robert Grant Aitken at the Lick Observatory. In 1935 he left to work at the Harvard College Observatory where he met Sarah Parker Fuller, whom he married on June 20, 1936. Although he had planned to move to Java to work at the Bosscha Observatory, he took a position at the Yerkes Observatory of the University of Chicago and became an American citizen in 1937. In 1949, Kuiper initiated the Yerkes–McDonald asteroid survey (1950–1952).
Kuiper discovered two natural satellites of planets in the Solar System, namely Uranus‘s satellite Miranda and Neptune‘s satellite Nereid. In addition, he discovered carbon dioxide in the atmosphere of Mars and the existence of a methane-laced atmosphere above Saturn‘s satellite Titan in 1944. Kuiper also pioneered airborne infrared observing using a Convair 990 aircraft in the 1960s.
Kuiper spent most of his career at the University of Chicago, but moved to Tucson, Arizona, in 1960 to found the Lunar and Planetary Laboratory at the University of Arizona. Kuiper was the laboratory’s director until his death in 1973 while on vacation with his wife in Mexico. One of the three buildings at Arizona that makes up the LPL is named in his honour.
Kuiper discovered several binary stars which received “Kuiper numbers” to identify them, such as KUI 79.
- In 1947, Kuiper was awarded the Prix Jules Janssen of the Astronomical Society of France.
- In 1959, Kuiper won the Henry Norris Russell Lectureship of the American Astronomical Society.
- In 1971, Kuiper received the Kepler Gold Medal from the American Association for the Advancement of Science and the Franklin Institute.
Astronomers refer to a region of small minor planets beyond Neptune as the “Kuiper belt“, since Kuiper had suggested that such small planets or comets may have formed there. However he believed that such objects would have been swept clear by planetary gravitational perturbations so that none or few would exist there today.
The Kuiper Prize, named in his honor, is the most distinguished award given by the American Astronomical Society‘s Division for Planetary Sciences, an international society of professional planetary scientists. The prize recognizes outstanding contributors to planetary science, and is awarded annually to scientists whose lifetime achievements have most advanced our understanding of planetary systems. Winners of this award include Carl Sagan, James Van Allen, and Eugene Shoemaker.
It Is Not A Sci-Fi Film!
Intergalactic dust is cosmic dust in between galaxies in intergalactic space. Evidence for intergalactic dust has been suggested as early as 1949, and study of it grew throughout the late 20th century. There are large variations in the distribution of intergalactic dust.
This is a clip from the Chandra website about elgordo.
•Scientists who discovered this galaxy cluster in 2012 nicknamed it “El Gordo” because of its gigantic mass.
•New data from Hubble indicate El Gordo may weigh 43 percent more than the original estimate.
•El Gordo is the most massive, the hottest, and gives off the most X-rays of any known cluster at its distance or beyond.
•Like the Bullet Cluster, El Gordo is the site of two galaxy clusters running into each other at several million miles per hour.El Gordo is located over 7 billion light years from Earth, meaning that it is being observed at a young age.
Comprehending the Huge Size of The Milky Way
It takes the Solar System about 240 million years to complete one orbit of the Galaxy (a Galactic year), so the Sun is thought to have completed 18–20 orbits during its lifetime and 1/1250 of a revolution since the origin of humans. The orbital speed of the Solar System about the center of the Galaxy is approximately 220 km/s or 0.073% of the speed of light. At this speed, it takes around 1,400 years for the Solar System to travel a distance of 1 light-year, or 8 days to travel 1 AU (astronomical unit). Galaxy rotation curve for the Milky Way. Vertical axis is speed of rotation about the Galactic Center. Horizontal axis is distance from the Galactic Center in kpcs. The Sun is marked with a yellow ball. The observed curve of speed of rotation is blue. The predicted curve based upon stellar mass and gas in the Milky Way is red. Scatter in observations roughly indicated by gray bars. The difference is due to dark matter.
The stars and gas in the Galaxy rotate about its center differentially, meaning that the rotation period varies with location. As is typical for spiral galaxies, the orbital speed of most stars in the Galaxy does not depend strongly on their distance from the center. Away from the central bulge or outer rim, the typical stellar orbital speed is between 210 and 240 km/s. Hence the orbital period of the typical star is directly proportional only to the length of the path traveled. This is unlike the situation within the Solar System, where two-body gravitational dynamics dominate and different orbits have significantly different velocities associated with them. The rotation curve (shown in the figure) describes this rotation. Toward the center of the galaxy the orbit speeds are too low while beyond 7 kpcs the speeds are too high to match what would be expected from the universal law of gravitation. If the Galaxy contained only the mass observed in stars, gas, and other baryonic (ordinary) matter, the rotation speed would decrease with distance from the center. However, the observed curve is relatively flat, indicating that there is additional mass that cannot be detected directly with electromagnetic radiation. This inconsistency is attributed to dark matter. Alternatively, a minority of astronomers propose that a modification of the law of gravity may explain the observed rotation curve. The Sun is near the inner rim of the Galaxy’s Orion Arm, within the Local Fluff of the Local Bubble, and in the Gould Belt, at a distance of 8.33 ± 0.35 kiloparsecs (27,200 ± 1,100 ly) from the Galactic Center. The Sun is currently 5–30 parsecs (16–98 ly) from the central plane of the Galactic disk. The distance between the local arm and the next arm out, the Perseus Arm, is about 2,000 parsecs (6,500 ly). The Sun, and thus the Solar System, is found in the Galactic habitable zone.
William Hyde Wollaston PRS (6 August 1766 – 22 December 1828) was an English chemist and physicist who is famous for discovering two chemical elements; he also developed a way to process platinum ore into malleable ingots.
Wollaston was born in East Dereham, Norfolk, the son of the priest-astronomer Francis Wollaston (1737–1815) and his wife Althea Hyde. The family, which included 17 children, was financially well-off and were part of an intellectually stimulating environment. Wollaston was educated at Gonville and Caius College, Cambridge: in 1793 he obtained a doctorate in medicine from Cambridge University, and was a fellow of his college from 1787 to 1828.
He worked as a physician in rural areas between 1793 and 1797, then moved to London. During his studies, Wollaston had become interested in chemistry, crystallography, metallurgy and physics. In 1800, after he had received a large sum of money from one of his older brothers, he left medicine. He concentrated on pursuing his interests in chemistry and other subjects outside his trained vocation.
He was elected a Fellow of the Royal Society in 1793, where he became an influential member. He served as president in 1820. In 1822 he was elected a Foreign Honorary Member of the American Academy of Arts and Sciences.
After having established a partnership with Smithson Tennant in 1800 in order to produce and sell chemical products, Wollaston became wealthy by developing the first physico-chemical method for processing platinum ore in practical quantities. He held the details of the process secret until near his death and made huge profits for about 20 years by being the only supplier in England of the product which had many of the same qualities as gold, but were much cheaper.
Anders Gustav Ekeberg discovered tantalum in 1802, however, Wollaston declared it was identical with niobium (then known as columbium). Later Heinrich Rose proved in 1846 that columbium and tantalum were indeed different elements and he renamed columbium “niobium“.
The mineral wollastonite was later named after Wollaston for his contributions to crystallography and mineral analysis.
Wollaston also performed important work in electricity. In 1801, he performed an experiment showing that the electricity from friction was identical to that produced by voltaic piles. During the last years of his life he performed electrical experiments that would pave the way to the eventual design of the electric motor. Controversy erupted when Michael Faraday constructed the first working electric motor and hastily published his results without acknowledging Wollaston’s previous work. Wollaston, however, saw nothing wrong with Faraday’s action. Wollaston also invented a battery that allowed the zinc plates in the battery to be raised out of the acid, so that the zinc would not be dissolved as quickly as it would if it were in the battery all the time.
His optical work was important as well, where he is remembered for his observations of dark Fraunhofer lines in the solar spectrum (1802), which eventually led to the discovery of the elements in the Sun. He invented the camera lucida (1807), the reflecting goniometer (1809), and the Wollaston prism. He also developed the first lens specifically for camera lens called Wollaston’s meniscus lens, or just meniscus lens, in 1812. The lens was designed to improve the image projected by the camera obscura. By changing the shape of the lens, Wollaston was able to project a flatter image, eliminating much of the distortion that was a problem with many of that day’s biconvex lenses.
Wollaston also devised a cryophorus, “a glass container containing liquid water and water vapor. It is used in physics courses to demonstrate rapid freezing by evaporation.” He used his Bakerian lecture in 1805, On the Force of Percussion, to defend Gottfried Leibniz‘s principle of vis viva, an early formulation of the conservation of energy. Wollaston was too ill to deliver his final Bakerian in 1828 and dictated it to Henry Warburton who read it on 20 November.
Wollaston’s attempt to demonstrate the presence of glucose in the blood serum of diabetics was unsuccessful due to the limited means of detection available to him. His 1811 paper “On the non-existence of sugar in the blood of persons labouring under diabetes mellitus” concluded that sugar must travel via lymphatic channels from the stomach directly to the kidneys, without entering the bloodstream. Wollaston supported this theory by referring to the thesis of a young medical student at Edinburgh, Charles Darwin (1758–1778), “Experiments establishing a criterion between mucaginous and purulent matter. And an account of the retrograde motions of the absorbent vessels of animal bodies in some diseases.” This Charles Darwin was the eldest son of Erasmus Darwin and not his more famous nephew, Charles Robert Darwin.
Wollaston prophetically foretold that if once an accurate knowledge were gained of the relative weights of elementary atoms, philosophers would not rest satisfied with the determination of mere numbers, but would have to gain a geometrical conception of how the elementary particles were placed in space. Jacobus Henricus van ‘t Hoff‘s La Chimie dans l’Espace was the first practical realisation of this prophecy.
Wollaston was part of a royal commission that recommended adoption of the imperial gallon in 1814. He served on the government’s Board of Longitude between 1818 and 1828 and was part of royal commission that opposed adoption of the metric system (1819).
Rosetta & Philae Make History
Quite a week for science and the E.S.A. – I have created this post as a summary to check back on. Not to reassure myself it actually happened but as a reference point!
Rosetta’s lander has completed its primary science mission after nearly 57 hours on Comet 67P/Churyumov–Gerasimenko.
After being out of communication visibility with the lander since 09:58 GMT / 10:58 CET on Friday, Rosetta regained contact with Philae at 22:19 GMT /23:19 CET last night. The signal was initially intermittent, but quickly stabilised and remained very good until 00:36 GMT / 01:36 CET this morning.
In that time, the lander returned all of its housekeeping data, as well as science data from the targeted instruments, including ROLIS, COSAC, Ptolemy, SD2 and CONSERT. This completed the measurements planned for the final block of experiments on the surface.
— ESA (@esa) November 16, 2014
Uranus and 27 Moon’s
Uranus, the seventh planet of the Solar System, has 27 known moons, all of which are named after characters from the works of William Shakespeare and Alexander Pope. William Herschel discovered the first two moons, Titania and Oberon, in 1787, and the other three ellipsoidal moons were discovered in 1851 by William Lassell (Ariel and Umbriel) and in 1948 by Gerard Kuiper (Miranda). These five have planetary mass, and so would be considered (dwarf) planets if they were in direct orbit about the Sun. The remaining moons were discovered after 1985, either during the Voyager 2 flyby mission or with the aid of advanced Earth-based telescopes.
Uranian moons are divided into three groups: thirteen inner moons, five major moons, and nine irregular moons. The inner moons are small dark bodies that share common properties and origins with the planet’s rings. The five major moons are massive enough to have achieved hydrostatic equilibrium, and four of them show signs of internally driven processes such as canyon formation and volcanism on their surfaces. The largest of these five, Titania, is 1,578 km in diameter and the eighth-largest moon in the Solar System, and about 20 times less massive than the Moon. Uranus’s irregular moons have elliptical and strongly inclined (mostly retrograde) orbits at great distances from the planet.
Joseph Fraunhofer, ennobled in 1824 as Ritter von Fraunhofer (6 March 1787 – 7 June 1826) was a German optician. He is known for the discovery of the dark absorption lines known as Fraunhofer lines in the Sun’s spectrum, and for making excellent optical glass and achromatic telescope objectives.
In physics and optics, the Fraunhofer lines are a set of spectral lines named after the German physicist Joseph von Fraunhofer (1787–1826) . The lines were originally observed as dark features (absorption lines) in the optical spectrum of the Sun.
In 1802, the English chemist William Hyde Wollaston was the first person to note the appearance of a number of dark features in the solar spectrum. In 1814, Fraunhofer independently rediscovered the lines and began a systematic study and careful measurement of the wavelength of these features. In all, he mapped over 570 lines, and designated the principal features with the letters A through K, and weaker lines with other letters. Modern observations of sunlight can detect many thousands of lines.
About 45 years later Kirchhoff and Bunsen noticed that several Fraunhofer lines coincide with characteristic emission lines identified in the spectra of heated elements. It was correctly deduced that dark lines in the solar spectrum are caused by absorption by chemical elements in the Solar atmosphere. Some of the observed features were identified as telluric lines originating from absorption in oxygen molecules in the Earth’s atmosphere.
The Fraunhofer lines are typical spectral absorption lines. These dark lines are produced whenever a cold gas is between a broad spectrum photon source and the detector. In this case, a decrease in the intensity of light in the frequency of the incident photon is seen as the photons are absorbed, then re-emitted in random directions, which are mostly in directions different from the original one. This results in an absorption line, since the narrow frequency band of light initially traveling toward the detector, has been turned into heat or re-emitted in other directions. By contrast, if the detector sees photons emitted directly from a glowing gas, then the detector often sees photons emitted in a narrow frequency range by quantum emission processes in atoms in the hot gas, resulting in an emission line. In the Sun, Fraunhofer lines are seen from gas in the outer regions of the Sun, which are too cold to directly produce emission lines of the elements they represent.
The surface area of Mimas is slightly less than the land area of Spain. The low density of Mimas, 1.15 g/cm³, indicates that it is composed mostly of water ice with only a small amount of rock. Due to the tidal forces acting on it, Mimas is noticeably prolate; its longest axis is about 10% longer than the shortest. The ellipsoidal shape of Mimas is especially noticeable in some recent images from the Cassini probe.
Mimas’s most distinctive feature is a giant impact crater 130 kilometres (81 mi) across, named Herschel after the discoverer of Mimas. Herschel’s diameter is almost a third of Mimas’s own diameter; its walls are approximately 5 kilometres (3.1 mi) high, parts of its floor measure 10 kilometres (6.2 mi) deep, and its central peak rises 6 kilometres (3.7 mi) above the crater floor. If there were a crater of an equivalent scale on Earth it would be over 4,000 kilometres (2,500 mi) in diameter, wider than Australia. The impact that made this crater must have nearly shattered Mimas: fractures can be seen on the opposite side of Mimas that may have been created by shock waves from the impact travelling through Mimas’s body.
The Mimantean surface is saturated with smaller impact craters, but no others are anywhere near the size of Herschel. Although Mimas is heavily cratered, the cratering is not uniform. Most of the surface is covered with craters greater than 40 kilometres (25 mi) in diameter, but in the south polar region, craters greater than 20 kilometres (12 mi) are generally lacking.
James Alfred Van Allen (September 7, 1914 – August 9, 2006) was an American space scientist at the University of Iowa. He was instrumental in establishing the field of magnetospheric research in space.
The Van Allen radiation belts were named after him, following their discovery by his Geiger–Müller tube instruments on the 1958 satellites: (Explorer 1, Explorer 3, and Pioneer 3) during the International Geophysical Year. Van Allen led the scientific community for the inclusion of scientific research instruments on space satellites.
About Van Allen
Born in Mount Pleasant, Iowa on September 7, 1914, Van Allen was valedictorian of his high school class in 1931, and received his bachelor’s degree in physics, summa cum laude, from Iowa Wesleyan College in 1935. While an undergraduate at Iowa Wesleyan, he assisted the senior scientist of the second Byrd Expedition (1934–35) to Antarctica in preparing seismic and magnetic experimental equipment. (In 2004, the American Polar Society commemorated his work by presenting Van Allen with its Honors of the Society award.) He earned his master’s and doctorate from the University of Iowa in 1936 and 1939, respectively.
From 1940 through 1942, he helped develop radio proximity fuzes—detonators to increase the effectiveness of anti-aircraft fire—for the defense of ships. Sponsored by the National Defense Research Council, his work was conducted at the Carnegie Institution of Washington and at the Applied Physics Laboratory of Johns Hopkins University. In November 1942, he was commissioned as a naval officer, and he served 16 months on various ships in the South Pacific Fleet as assistant staff gunnery officer.
In 1946, Van Allen returned to the Applied Physics Laboratory where he organized and directed a team to conduct high-altitude experimental work using V2 and Aerobee rockets, and, in 1951, he accepted a Guggenheim research fellowship at the Brookhaven National Laboratory.
Later in 1951, Van Allen became professor and head of the University of Iowa Department of Physics and Astronomy, a position he held until he retired from teaching in 1985. During the 1950s, he and his graduate students used the UI football practice field to launch rockets and “rockoons”—rockets carried aloft by balloons—to conduct cosmic ray experiments above the atmosphere. A highlight of that work was the 1953 discovery of electrons believed to be the driving force behind the aurora. In 1956, he proposed the use of U.S. satellites for cosmic-ray investigations and through “preparedness and good fortune,” he later wrote, the experiment was selected as the principal payload for the first flight of a four-stage Juno I rocket in October 1957.
Van Allen played an important role in planning the 1957-58 International Geophysical Year (IGY) and carried out shipboard expeditions to Greenland and southward to the Ross Sea off the coast of Antarctica in 1957. IGY culminated in the Jan. 31, 1958 launch of Explorer 1 and its scientific payload. Van Allen’s instruments included a Geiger–Müller tube, which provided data and information that regions of intense radiation surround the Earth. The discovery marked the birth of the research field of magnetospheric physics, an enterprise that grew to involve more than 1,000 investigators in more than 20 countries.
In 1974 People Magazine listed Van Allen as one of the top 10 teaching college professors in the country. His former graduate students list among their accomplishments experiments on NASA’s Pioneer 10 and 11, Voyager 1 and 2, Galileo and Cassini spacecraft. Van Allen joined the American Geophysical Union (AGU) in 1948 and served as the organization’s president from 1982 until 1984. He has received the AGU’s highest honors, including the John A. Fleming Award in 1963 for eminence in geophysics and the William Bowie Medal in 1977 for outstanding contributions to fundamental geophysics and for unselfish cooperation in research.
Also, in 1962 Van Allen became the second recipient of the Daniel and Florence Guggenheim International Astronautical Award presented by the International Academy of Astronautics for noteworthy contributions to astronautics, and in March 2006 he received the 2006 Smithsonian National Air and Space Museum Trophy for lifetime achievement. In 1994, Van Allen received the 1994 Gerard P. Kuiper Prize from the Division of Planetary Sciences of the American Astronomical Society “in recognition of his many contributions to the field of planetary science, both through his investigations of planetary magnetospheres and through his advocacy of planetary exploration.” Also in 1994, he was presented with a lifetime
achievement award by NASA on the occasion of his 80th birthday and the American Geophysical Union’s 75th anniversary.
Aerobee and Rockoon
Discharged from the Navy in 1946, Van Allen returned to civilian research at APL. He organized and directed a team at Johns Hopkins University to conduct high-altitude experiments, using V-2 rockets captured from the Germans at the end of World War II. Van Allen decided a small sounding rocket was needed for upper atmosphere research and the Aerojet WAC Corporal and the Bumblebee missile were developed under a US Navy program. He drew specifications for the Aerobee and headed the committee that convinced the U.S. government to produce it. The first instrument-carrying Aerobee was the A-5, launched on March 5, 1948 from White Sands, carrying instruments for cosmic radiation research, reaching an altitude of 117.5 km.
Van Allen elected chairman of the V-2 Upper Atmosphere Panel on December 29, 1947. The panel was renamed Upper Atmosphere Rocket Research Panel on March 18, 1948; then Rocket and Satellite Research Panel on April 29, 1948. The panel suspended operations on May 19, 1960 and had a reunion on February 2, 1968.
Cmdr. Lee Lewis, Cmdr. G. Halvorson, S.F. Singer, and James A. Van Allen develop the idea for the Rockoon on March 1, 1949 during the Aerobee rocket firing cruise on the research vessel U.S.S. Norton Sound.
On April 5, 1950 Van Allen left Applied Physics Laboratories, to accept a John Simon Guggenheim Memorial Foundation research fellowship at the Brookhaven National Laboratory. The following year (1951) Van Allen accepted the position as head of the physics department at the University of Iowa. Before long, he was enlisting students in his efforts to discover the secrets of the wild blue yonder and inventing ways to carry instruments higher into the atmosphere than ever before. By 1952, Van Allen was the first to devise a balloon-rocket combination that lifted rockets on balloons high above most of the Earth’s atmosphere before firing them even higher. The rockets were ignited after the balloons reached an altitude of 16 kilometers.
As Time magazine reported in 1959, “Van Allen’s ‘Rockoons’ could not be fired in Iowa for fear that the spent rockets would strike an Iowan or his house.” So Van Allen convinced the U.S. Coast Guard to let him fire his rockoons from the icebreaker Eastwind that was bound for Greenland. “The first balloon rose properly to 70,000 ft., but the rocket hanging under it did not fire. The second Rockoon behaved in the same maddening way. On the theory that extreme cold at high altitude might have stopped the clockwork supposed to ignite the rockets, Van Allen heated cans of orange juice, snuggled them into the third Rockoon’s gondola, and wrapped the whole business in insulation. The rocket fired.”
In 1953 the Rockoons and their science payloads fired off Newfoundland detected the first hint of radiation belts surrounding Earth. The low-cost Rockoon technique was later used by the Office of Naval Research and The University of Iowa research groups in 1953-55 and 1957, from ships at sea between Boston and Thule, Greenland.
In 1954, in a private discussion about the Redstone project with Ernst Stuhlinger, Wernher von Braun expressed his belief that they should have a “real, honest-to-goodness scientist” involved in their little unofficial satellite project. “I’m sure you know a scientist somewhere who would fill the bill, possibly in the Nobel Prize class, willing to work with us and to put some instruments on our satellite.” Stuhlinger, himself a cosmic ray researcher during his college years, and having worked with Van Allen at White Sands with V-2 rockets, was ready with his reply: “Yes, of course, I will talk to Dr. Van Allen.”
Stuhlinger followed this by a visit with Van Allen at his home in Princeton, New Jersey, where Van Allen was on sabbatical leave from Iowa to work on stellarator design. Van Allen later recounted, “Stuhlinger’s 1954 message was simple and eloquent. By virtue of ballistic missile developments at Army Ballistic Missile Agency (ABMA), it was realistic to expect that within a year or two a small scientific satellite could be propelled into a durable orbit around the earth (Project Orbiter)…. I expressed a keen interest in performing a worldwide survey of the cosmic-ray intensity above the atmosphere.”
In 1955, the U.S. announced Project Vanguard as part of the US contribution to the International Geophysical Year, a project to launch an artificial satellite into an orbit around the Earth. It was to be run by the US Navy and to be based on developing sounding rockets, which had the advantage that they were primarily used for non-military scientific experiments.
The symposium on “The Scientific Uses of Earth Satellites” was held on January 26 and 27, 1956 at the University of Michigan under sponsorship of the Upper Atmosphere Rocket Research Panel, chaired by Dr. Van Allen. 33 scientific proposals were presented for inclusion in the IGY satellites. Van Allen’s presentation highlighted the use of planned U.S. satellites for continuing cosmic-ray investigations. At this same time his Iowa Group began preparations for scientific research instruments to be carried by ‘Rockoons‘ and Vanguard for the International Geophysical Year. Through “preparedness and good fortune,” as he later wrote, those scientific instruments were available for incorporation in the 1958 Explorer and Pioneer IGY launches.
Van Allen Probes
On Nov. 9, 2012 NASA renamed the Radiation Belt Storm Probes (RBSP), a mission to study Earth’s Van Allen radiation belts, as the Van Allen Probes mission in honor of the late James A. Van Allen, U.S. space pioneer and longtime distinguished professor of physics in the University of Iowa College of Liberal Arts and Sciences. The Applied Physics Laboratory, where Dr. Van Allen worked for a decade, is responsible for the overall implementation and instrument management for RBSP. The primary mission is scheduled to last 2 years, with expendables expected to last for 4 years.
Draco is a constellation in the far northern sky.
Draco is a constellation in the far northern sky. Its name is Latin for dragon. Draco is circumpolar (that is, never setting) for many observers in the northern hemisphere. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations today. The north pole of the ecliptic is in Draco. Draco can be seen all year.
Thuban (a Draconis) was the northern pole star from 3942 BC, when it moved farther north than Theta Boötis, until 1793 BC. The Egyptian Pyramids were designed to have one side facing north, with an entrance passage designed so that Thuban would be visible at night. Due to the effects of precession, it will once again be the pole star around the year 21000 AD. It is a blue-white giant star of magnitude 3.7, 309 light-years from Earth. The traditional name of Alpha Draconis, Thuban, means “head of the serpent”.
There are two other stars above magnitude 3 in Draco. The brighter of the two—and the brightest star in Draco—is Gamma Draconis, traditionally called Etamin or Eltanin. It is an orange giant star of magnitude 2.2, 148 light-years from Earth. The aberration of starlight was discovered in 1728 when James Bradley observed Gamma Draconis. Beta Draconis, traditionally called Rastaban, is a yellow giant star of magnitude 2.8, 362 light-years from Earth. Its name shares a meaning with Thuban, “head of the serpent”.
Draco is home to several double stars and binary stars. Draconis is a double star with a yellow-hued primary of magnitude 2.8 and a white-hued secondary of magnitude 8.2 located south of the primary. The two are separated by 4.8 arcseconds. Mu Draconis, traditionally called Alrakis, is a binary star with two white components. Magnitude 5.6 and 5.7, the two components orbit each other every 670 years. The Alrakis system is 88 light-years from Earth. Nu Draconis is a similar binary star with two white components, 100 light-years from Earth. Both components are of magnitude 4.9 and can be distinguished in a small amateur telescope or a pair of binoculars. Omicron Draconis is a double star divisible in small telescopes. The primary is an orange giant of magnitude 4.6, 322 light-years from Earth.
The secondary is of magnitude 7.8. Psi Draconis is a binary star divisible in binoculars and small amateur telescopes, 72 light-years from Earth. The primary is a yellow-white star
of magnitude 4.6 and the secondary is a yellow star of magnitude 5.8. 16 Draconis and 17 Draconis are part of a triple star 400 light-years from Earth, divisible in medium-sized
amateur telescopes. The primary, a blue-white star of magnitude 5.1, is itself a binary with components of magnitude 5.4 and 6.5. The secondary is of magnitude 5.5 and the
system is 400 light-years away. 20 Draconis is a binary star with a white-hued primary of magnitude 7.1 and a yellow-hued secondary of magnitude 7.3 located east-northeast of the
primary. The two are separated by 1.2 arc seconds at their maximum and have an orbital period of 420 years. As of 2012, the two components are approaching their maximum
separation. 39 Draconis is a triple star 188 light-years from Earth, divisible in small amateur telescopes. The primary is a blue star of magnitude 5.0, the secondary is a yellow star of magnitude 7.4, and the tertiary is a star of magnitude 8.0; the tertiary appears to be a close companion to the primary. 40 Draconis and 41 Draconis are a binary star divisible in small telescopes. The two orange dwarf stars are 170 light-years from Earth and are of magnitude 5.7 and 6.1.
R Draconis is a red Mira-type variable star with a period of about 8 months. Its average minimum magnitude is approximately 12.4, and its average maximum magnitude is approximately 7.6. It was discovered to be a variable star by Hans Geelmuyden in 1876.
The constellation contains the star recently named Kepler-10 which has been confirmed to be orbited by Kepler-10b, the smallest ever rocky Earth-sized planet detected outside of our solar system.
The Deep-sky Objects in Draco
One of the deep-sky objects in Draco is the Cat’s Eye Nebula (NGC 6543), a planetary nebula approximately 3,000 light-years away that was discovered by English astronomer William Herschel in 1786. It is 9th magnitude and was named for its appearance in the Hubble Space Telescope, though it appears as a fuzzy blue-green disk in an amateur telescope.NGC 6543 has a very complex shape due to gravitational interactions between the components of the multiple star at its center, the progenitor of the nebula approximately 1,000 years ago. It is located 9.6 arcminutes away from the north ecliptic pole to the west-northwest. It is also related to IC 4677, a nebula that appears as a bar 1.8 arcminutes to the west of the Cat’s Eye nebula. In long-term exposures, IC 4677 appears as a portion of a ring surrounding the planetary nebula.
There are several faint galaxies in Draco, one of which is the lenticular galaxy NGC 5866, sometimes considered to be Messier Object 102. Another is the Draco Dwarf Galaxy, one of the least luminous galaxies with an absolute magnitude of -8.6 and a diameter of only about 3,500 light years, discovered by Albert G. Wilson of Lowell Observatory in 1954.
Another dwarf galaxy found in this constellation is PGC 39058.
Draco also features several interacting galaxies and galaxy clusters. One such massive cluster is Abell 2218, located at a distance of 3 billion light-years (redshift 0.171). It acts as a gravitational lens for even more distant background galaxies, allowing astronomers to study those galaxies as well as Abell 2218 itself; more specifically, the lensing effect allows
astronomers to confirm the cluster’s mass as determined by x-ray emissions. One of the most well-known interacting galaxies is Arp 188, also called the “Tadpole Galaxy”.
Named for its appearance, which features a “tail” of stars 280,000 light-years long, the Tadpole Galaxy is at a distance of 420 million light-years (redshift 0.0314). The tail of stars drawn off the Tadpole Galaxy appears blue because the gravitational interaction disturbed clouds of gas and sparked star formation.
Q1634+706 is a quasar that holds the distinction of being the most distant object usually visible in an amateur telescope. At magnitude 14.4, it appears starlike, though it is at a distance of 12.9 billion light-years. The light of Q1634+706 has taken 8.6 billion years to reach Earth, a discrepancy attributable to the expansion of the universe.
Dragons in Greek mythology that may have inspired the constellation’s name include Ladon, the dragon who guarded the golden apples of the Hesperides. Hercules killed Ladon during his 12 labors; he was tasked with stealing the golden apples. The constellation of Hercules is depicted near Draco.
In Greco- Roman legend, Draco was a dragon killed by the goddess Minerva and tossed into the sky upon his defeat. The dragon was one of the Gigantes, who battled the Olympic gods for ten years. As Minerva threw the dragon, it became twisted on itself and froze at the cold North Celestial Pole before it could right itself. Sometimes, Draco is represented as the demon son of Gaia, Typhon.
Traditional Arabic astronomy does not depict a dragon in modern-day Draco, which is called the Mother Camels. Instead, two hyenas, represented by Eta Draconis and Zeta Draconis are seen attacking a baby camel (a dim star near Beta Draconis), which is protected by four female camels, represented by Beta Draconis, Gamma Draconis, Nu Draconis, and Xi Draconis. The nomads who own the camels are camped nearby, represented by a cooking tripod composed of Upsilon, Tau, and Sigma Draconis.
In some mythology, Draco the dragon constellation had one- hundred magnificent heads, and gourded the golden apple tree, and put in the sky as a constellation for his bravery at protecting the apples. There are more myths than that, but that is one of the most common ones.
Not easy to see with the naked eye
Lacerta is one of the 88 modern constellations defined by the International Astronomical Union. Its name is Latin for lizard. A small, faint constellation, it was created in 1687 by the astronomer Johannes Hevelius. Its brightest stars form a “W” shape similar to that of Cassiopeia, and it is thus sometimes referred to as ‘Little Cassiopeia’. It is located between Cygnus, Cassiopeia and Andromeda on the northern celestial sphere. The northern part lies on the Milky Way.
Stars in Lacerta
Alpha Lacertae is a blue-white hued main-sequence star of magnitude 3.8, 102 light-years from Earth. It has a spectral type of A1 V and is an optical double star. Beta Lacertae is far dimmer, a yellow giant of magnitude 4.4, 170 light-years from Earth.
Roe 47 is a multiple star consisting of five components (magnitudes 5.8, 9.8, 10.1, 9.4, 9.8).
ADS 16402 is a binary star system in Lacerta, around which a planet orbits with some unusual properties. The Jupiter-sized planet exhibits an unexpectedly low density, about the same as cork. This planet is dubbed HAT P-1.
EV Lacertae is a rapidly spinning magnitude 10 red dwarf with a strong magnetic field. It is a flare star that can emit powerful flares potentially visible to the naked eye, thousands of times more energetic than any from Earth’s sun.
Need to know what is meant by the term hot jupiters?
Hot Jupiters (also called roaster planets, epistellar jovians, pegasids or pegasean planets) are a class of extrasolar planets whose characteristics are similar to Jupiter, but that have high surface temperatures because they orbit very close—between approximately 0.015 and 0.5 astronomical units (2.2×10^6 and 74.8×10^6 km)—to their parent stars, whereas Jupiter orbits its parent star (the Sun) at 5.2 astronomical units (780×10^6 km), causing low surface temperatures.
One of the best-known hot Jupiters is 51 Pegasi b, nicknamed Bellerophon. Discovered in 1995, it was the first extrasolar planet found orbiting a Sun-like star. 51 Pegasi b has an orbital period of about 4 days.
Hot Jupiters have some common characteristics:
- They have similar characteristics to Jupiter (gas giants, usually with masses close to or exceeding that of Jupiter, which is 1.9×1027 kg), however, orbit much more closely to the star and experience a high surface temperature.
- They have a much greater chance of transiting their star as seen from a farther outlying point than planets of the same mass in larger orbits. The most notable of these are HD 209458 b, the first transiting hot Jupiter found, HD 189733 b, which was first mapped in 2007 by the Spitzer Space Telescope, and HAT-P-7b, which was recently observed by the Kepler mission.
- Due to high levels of insolation they are of a lower density than they would otherwise be. This has implications for radius determination, because due to limb darkening of the planet’s background star during a transit, the planet’s ingress and egress boundaries are harder to determine.
- They are all thought to have migrated to their present positions because there would not have been enough material so close to the star for a planet of that mass to have formed in situ.
- Most of these have nearly circular orbits (low eccentricities). This is because their orbits have been circularized, or are being circularized, by the process of libration.
- They exhibit high-speed winds distributing the heat from the day side to the night side, thus the temperature difference between the two sides is relatively low.
- They are more common around F- and G-type stars and somewhat less common around K-type stars. Hot Jupiters around red dwarfs are very rare.
Hot Jupiters are the easiest extrasolar planets to detect via the radial-velocity method, because the oscillations they induce in their parent stars’ motion are relatively large and rapid, compared to other known types of planets.
They are thought to form at a distance from the star beyond the frost line, where the planet can form from rock, ice and gases. The planets then migrate inwards to the star where they eventually form a stable orbit. The planets usually move by type 2 migrations, or possibly via interaction with other planets. The migration happens during the solar nebula phase, and will typically stop when the star enters its T-Tauri phase. The strong stellar winds at this time remove most of the remaining nebula.
After their atmospheres and outer layers are stripped away (hydrodynamic escape), their cores may become chthonian planets. The amount of the outermost layers that is lost depends on the size and the material of the planet and the distance from the star. In a typical system a gas giant orbiting 0.02 AU around its parent star loses 5–7% of its mass during its lifetime, but orbiting closer than 0.015 AU can mean evaporation of the whole planet except for its core.
Terrestrial planets in systems with hot Jupiters
Simulations have shown that the migration of a Jupiter-sized planet through the inner protoplanetary disk (the region between 5 and 0.1 AU from the star) is not as destructive as one might assume. More than 60% of the solid disk materials in that region are scattered outward, including planetesimals and protoplanets, allowing the planet-forming disk to reform in the gas giant’s wake. In the simulation, planets up to two Earth masses were able to form in the habitable zone after the hot Jupiter passed through and its orbit stabilized at 0.1 AU. Due to the mixing of inner-planetary-system material with outer-planetary-system material from beyond the frost line, simulations indicated that the terrestrial planets that formed after a hot Jupiter’s passage would be particularly water-rich.
It has been found that several hot Jupiters have retrograde orbits and this calls into question the theories about the formation of planetary systems, although rather than a planet’s orbit having been disturbed, it may be that the star itself flipped over early in their system’s formation due to interactions between the star’s magnetic field and the planet-forming disc. By combining new observations with the old data it was found that more than half of all the hot Jupiters studied have orbits that are misaligned with the rotation axis of their parent stars, and six exoplanets in this study have retrograde motion.
Five ultra-short-period planets have been identified in the region of the Milky Way known as the galactic bulge. They were observed by the Hubble Space Telescope and first described by researchers from the Space Telescope Science Institute, the Universidad Catolica de Chile, Uppsala University, the High Altitude Observatory, the INAF–Osservatorio Astronomico di Padova and the University of California at Los Angeles.
In 1911, Bohr travelled to England. At the time, it was where most of the theoretical work on the structure of atoms and molecules was being done. He met J. J. Thomson of the Cavendish Laboratory and Trinity College, Cambridge. He attended lectures on electromagnetism given by James Jeans and Joseph Larmor, and did some research on cathode rays, but failed to impress Thomson. He had more success with younger physicists like the Australian William Lawrence Bragg, and New Zealand’s Ernest Rutherford, whose 1911 Rutherford model of the atom had challenged Thomson’s 1904 plum pudding model.
Bohr received an invitation from Rutherford to conduct post-doctoral work
at Victoria University of Manchester, where Bohr met George de Hevesy and Charles Galton Darwin (whom Bohr referred to as “the grandson of the real Darwin”).
Bohr returned to Denmark in July 1912 for his wedding, and travelled around England and Scotland on his honeymoon. On his return, he became a privatdocent at the University of Copenhagen, giving lectures on thermodynamics. Martin Knudsen put Bohr’s name forward for a docent, which was approved in July 1913, and Bohr then began teaching medical students. His three papers, which later became famous as “the trilogy”, were published in Philosophical Magazine in July, September and November of that year. He adapted Rutherford’s nuclear structure to Max Planck’s quantum theory and so created his Bohr model of the atom.
Planetary models of atoms were not new, but Bohr’s treatment was. Taking the 1912 paper by Darwin on the role of electrons in the interaction of alpha particles with a nucleus as his starting point, he advanced the theory of electrons travelling in orbits around the atom’s nucleus, with the chemical properties of each element being largely determined by the number of electrons in the outer orbits of its atoms. He introduced the idea that an electron could drop from a higher-energy orbit to a lower one, in the process emitting a quantum of discrete energy. This became a basis for what is now known as the old quantum theory.
In atomic physics, the Rutherford–Bohr model or Bohr model, introduced by Niels Bohr in 1913, depicts the atom as a small, positively charged nucleus surrounded by electrons that travel in circular orbits around the nucleus—similar in structure to the solar system, but with attraction provided by electrostatic forces rather than gravity. After the cubic model (1902), the plum-pudding model (1904), the Saturnian model (1904), and the Rutherford model (1911) came the Rutherford–Bohr model or just Bohr model for short (1913). The improvement to the Rutherford model is mostly a quantum physical interpretation of it. The Bohr model has been superseded, but the quantum theory remains sound.
The model’s key success lay in explaining the Rydberg formula for the spectral emission lines of atomic hydrogen. While the Rydberg formula had been known experimentally, it did not gain a theoretical underpinning until the Bohr model was introduced. Not only did the Bohr model explain the reason for the structure of the Rydberg formula, it also provided a justification for its empirical results in terms of fundamental physical constants.
The Bohr model is a relatively primitive model of the hydrogen atom, compared to the valence shell atom. As a theory, it can be derived as a first-order approximation of the hydrogen atom using the broader and much more accurate quantum mechanics and thus may be considered to be an obsolete scientific theory. However, because of its simplicity, and its correct results for selected systems (see below for application), the Bohr model is still commonly taught to introduce students to quantum mechanics or energy level diagrams before moving on to the more accurate, but more complex, valence shell atom. A related model was originally proposed by Arthur Erich Haas in 1910, but was rejected. The quantum theory of the period between Planck’s discovery of the quantum (1900) and the advent of a full-blown quantum mechanics (1925) is often referred to as the old quantum theory.
The Story of Niels Henrik David Bohr
Niels Bohr (7 October 1885 – 18 November 1962) was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory, for which he received the Nobel Prize in Physics in 1922. Bohr was also a philosopher and a promoter of scientific research.
Bohr developed the Bohr model of the atom, in which he proposed that energy levels of electrons are discrete and that the electrons revolve in stable orbits around the atomic nucleus but can jump from one energy level (or orbit) to another. Although the Bohr model has been supplanted by other models, its underlying principles remain valid. He conceived the principle of complementarity: that items could be separately analysed in terms of contradictory properties, like behaving as a wave or a stream of particles. The notion of complementarity dominated Bohr’s thinking in both science and philosophy.
Bohr founded the Institute of Theoretical Physics at the University of Copenhagen, now known as the Niels Bohr Institute, which opened in 1920. Bohr mentored and collaborated with physicists including Hans Kramers, Oskar Klein, George de Hevesy and Werner Heisenberg. He predicted the existence of a new zirconium-like element, which was named hafnium, after the Latin name for Copenhagen, where it was discovered. Later, the element bohrium was named after him.
During the 1930s, Bohr helped refugees from Nazism. After Denmark was occupied by the Germans, he had a famous meeting with Heisenberg, who had become the head of the German nuclear energy project. In September 1943, word reached Bohr that he was about to be arrested by the Germans, and he fled to Sweden. From there, he was flown to Britain, where he joined the British Tube Alloys nuclear weapons project, and was part of the British mission to the Manhattan Project. After the war, Bohr called for international cooperation on nuclear energy. He was involved with the establishment of CERN and the Research Establishment Risø of the Danish Atomic Energy Commission, and became the first chairman of the Nordic Institute for Theoretical Physics in 1957.
Niels Bohr was born in Copenhagen, Denmark, on 7 October 1885, the second of three children of Christian Bohr, a professor of physiology at the University of Copenhagen, and Ellen Adler Bohr, who came from a wealthy Danish Jewish family prominent in banking and parliamentary circles. He had an elder sister, Jenny, and a younger brother Harald. Jenny became a teacher, while Harald became a mathematician and Olympic footballer who played for the Danish national team at the 1908 Summer Olympics in London. Niels was a passionate footballer as well, and the two brothers played several matches for the Copenhagen-based Akademisk Boldklub, with Niels as goalkeeper.
Bohr was educated at Gammelholm Latin School, starting when he was seven. In 1903, Bohr enrolled as an undergraduate at Copenhagen University. His major was physics, which he studied under Professor Christian Christiansen, the university’s only professor of physics at that time. He also studied astronomy and mathematics under Professor Thorvald Thiele, and philosophy under Professor Harald Høffding, a friend of his father.
In 1905, a gold medal competition was sponsored by the Royal Danish Academy of Sciences and Letters to investigate a method for measuring the surface tension of liquids that had been proposed by Lord Rayleigh in 1879. This involved measuring the frequency of oscillation of the radius of a water jet. Bohr conducted a series of experiments using his father’s laboratory in the university; the university itself had no physics laboratory. To complete his experiments, he had to make his own glassware, creating test tubes with the required elliptical cross-sections. He went beyond the original task, incorporating improvements into both Rayleigh’s theory and his method, by taking into account the viscosity of the water, and by working with finite amplitudes instead of just infinitesimal ones. His essay, which he submitted at the last minute, won the prize. He later submitted an improved version of the paper to the Royal Society in London for publication in the Philosophical Transactions of the Royal Society.
Harald became the first of the two Bohr brothers to earn a master’s degree, which he earned for mathematics in April 1909. Niels took another nine months to earn his. Students had to submit a thesis on a subject assigned by their supervisor. Bohr’s supervisor was Christiansen, and the topic he chose was the electron theory of metals. Bohr subsequently elaborated his master’s thesis into his much larger Doctor of Philosophy (dr. phil.) thesis. He surveyed the literature on the subject, settling on a model postulated by Paul Drude and elaborated by Hendrik Lorentz, in which the electrons in a metal are considered to behave like a gas. Bohr extended Lorentz’s model but was still unable to account for phenomena like the Hall effect, and concluded that electron theory could not fully explain the magnetic properties of metals. The thesis was accepted in April 1911, and Bohr conducted his formal defence on 13 May. Harald had received his doctorate the previous year. Bohr’s thesis was ground breaking, but attracted little interest outside Scandinavia because it was written in Danish, a Copenhagen University requirement at the time. In 1921, the Dutch physicist Hendrika Johanna van Leeuwen would independently derive a theorem from Bohr’s thesis that is today known as the Bohr–van Leeuwen theorem.
An atomic orbital is a mathematical function that describes the wave-like behavior of either one electron or a pair of electrons in an atom. This function can be used to calculate the probability of finding any electron of an atom in any specific region around the atom’s nucleus. The term may also refer to the physical region or space where the electron can be calculated to be present, as defined by the particular mathematical form of the orbital.
Each orbital in an atom is characterized by a unique set of values of the three quantum numbers n, ℓ, and m, which correspond to the electron’s energy, angular momentum, and an angular momentum vector component, respectively. Any orbital can be occupied by a maximum of two electrons, each with its own spin quantum number. The simple names s orbital, p orbital, d orbital and f orbital refer to orbitals with angular momentum quantum number ℓ = 0, 1, 2 and 3 respectively. These names, together with the value of n, are used to describe the electron configurations. They are derived from the description by early spectroscopists of certain series of alkali metal spectroscopic lines as sharp, principal, diffuse, and fundamental. Orbitals for ℓ > 3 are named in alphabetical order (omitting j).
Atomic orbitals are the basic building blocks of the atomic orbital model (alternatively known as the electron cloud or wave mechanics model), a modern framework for visualizing the submicroscopic behavior of electrons in matter. In this model the electron cloud of a multi-electron atom may be seen as being built up (in approximation) in an electron configuration that is a product of simpler hydrogen-like atomic orbitals. The repeating periodicity of the blocks of 2, 6, 10, and 14 elements within sections of the periodic table arises naturally from the total number of electrons that occupy a complete set of s, p, d and f atomic orbitals, respectively.
Emanuel Swedenborg born Emanuel Swedberg on 29 January 1688; died 29 March 1772) was a Swedish scientist, philosopher, theologian, revelator, and mystic. He is best known for his book on the afterlife, Heaven and Hell (1758).
Swedenborg had a prolific career as an inventor and scientist. In 1741, at age 53, he entered into a spiritual phase in which he began to experience dreams and visions, beginning on Easter weekend of April 6, 1744. This culminated in a ‘spiritual awakening’, in which he received revelation that he was appointed by the Lord to write The Heavenly Doctrine to reform Christianity. According to The Heavenly Doctrine the Lord had opened Swedenborg’s spiritual eyes, so that from then on he could freely visit heaven and hell and talk with angels, demons and other spirits; and the Last Judgment had already occurred, in 1757. However, he tells us that at this day it is very dangerous to talk with spirits, unless a person is in true faith, and is led by the Lord.
For the remaining 28 years of his life, Swedenborg wrote 18 published theological works, and several more which were unpublished. He termed himself a “Servant of the Lord Jesus Christ” in True Christian Religion, a work he published himself. Some followers of The Heavenly Doctrine believe that, of his theological works, only those which Swedenborg published himself are fully divinely inspired.
In 1715 Swedenborg returned to Sweden, where he devoted himself to natural science and engineering projects for the next two decades. A first step was his meeting with King Charles XII of Sweden in the city of Lund, in 1716. The Swedish inventor Christopher Polhem, who became a close friend of Swedenborg, was also present. Swedenborg’s purpose was to persuade the king to fund an observatory in northern Sweden.
From 1716 to 1718, Swedenborg published a scientific periodical entitled Daedalus Hyperboreus (“The Northern Daedalus“), a record of mechanical and mathematical inventions and discoveries. One notable description was that of a flying machine, the same he had been sketching a few years earlier (see Flying Machine (Swedenborg)).
In 1718 Swedenborg published an article that attempted to explain spiritual and mental events in terms of minute vibrations or “tremulations”.
Upon the death of Charles XII, Queen Ulrika Eleonora ennobled Swedenborg and his siblings. It was common in Sweden during the 17th and 18th centuries for the children of bishops to receive this honour as a recognition of the services of their father. The family name was changed from Swedberg to Swedenborg.
In 1724, he was offered the chair of mathematics at Uppsala University, but he declined and said that he had mainly dealt with geometry, chemistry and metallurgy during his career. He also said that he did not have the gift of eloquent speech because of a stutter, as recognized by many acquaintances of his; it forced him to speak slowly and carefully, and there are no known occurrences of his speaking in public. The Swedish critic Olof Lagerkrantz proposed that Swedenborg compensated for his impediment by extensive argumentation in writing.
September Orion Sight
I have just seen Orion for the first time with my naked eye, in 2014. A beautiful site creeping up behind a tree from my window view. The only bad part of that is – it means winter is on it’s way already!
The Orion constellation is in my opinion, by far the most glorious of all to see.
Eridanus is a large constellation represented as a river.
It’s name is the Ancient Greek name for the Po River. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations. It is the sixth largest of the modern constellations.
The Stars of Eridanis
At its southern end is the magnitude 0.5 star Achernar, designated Alpha Eridani. 144 light-years from Earth, it is a blue-white hued main sequence star whose traditional name means “the river’s end”. Achernar is a very peculiar star because it is one of the flattest stars known. Observations indicate that its radius is about 50% larger at the equator than at the poles. This distortion occurs because the star is spinning extremely rapidly.
There are several other noteworthy stars in Eridanus, including some double stars. Beta Eridani, traditionally called Cursa, is a blue-white star of magnitude 2.8, 89 light-years from Earth. Its place to the south of Orion’s foot gives it its name, which means “the footstool”. Theta Eridani, called Acamar, is a binary star with blue-white components, distinguishable in small amateur telescopes and 161 light-years from Earth.
The primary is of magnitude 3.2 and the secondary is of magnitude 4.3. 32 Eridani is a binary star 290 light-years from Earth. The primary is a yellow-hued star of magnitude 4.8 and the secondary is a blue-green star of magnitude 6.1. 32 Eridani is divisible in small amateur telescopes. 39 Eridani is a binary star divisible in small amateur telescopes, 206 light-years from Earth. The primary is an orange-hued giant star of magnitude 4.9 and the secondary is of magnitude 8. 40 Eridani is a triple star system consisting of an orange main-sequence star, a white dwarf, and a red dwarf.
The orange main-sequence star is the primary of magnitude 4.4, and the white secondary of magnitude 9.5 is the most easily visible white dwarf. The red dwarf, of magnitude 11, orbits the white dwarf every 250 years. The 40 Eridani system is 16 light-years from Earth. p Eridani is a binary star with two orange components, 27 light-years from Earth. The magnitude 5.8 primary and 5.9 secondary have an orbital period of 500 years.
Epsilon Eridani is a star with one extrasolar planet similar to Jupiter. It is an orange-hued main-sequence star of magnitude 3.7, 10.5 light-years from Earth. Its one planet, with an approximate mass of one Jupiter mass, has a period of 7 years.
NGC 1535 is a small blue-gray planetary nebula visible in small amateur telescopes, with a disk visible in large amateur instruments. 2000 light-years away, it is of the 9th magnitude.
Eridanus contains the galaxies NGC 1232, NGC 1234 and NGC 1300, a grand design barred spiral galaxy.
NGC 1300 is a face-on barred spiral galaxy located 61 (plus or minus 8) million light-years away. The center of the bar shows an unusual structure: within the overall spiral structure, a grand design spiral that is 3,300 light-years in diameter exists. Its spiral arms are tightly wound.
The Nu Eridanids, a recently discovered meteor shower, radiate from the constellation between August 30 and September 12 every year; the shower’s parent body is an unidentified Oort cloud object. Another meteor shower in Eridanus is the Omicron Eridanids, which peak between November 1 and 10.
Astronomy Pioneer Jan Oort
Jan Oort (28 April 1900 – 5 November 1992) was a Dutch astronomer who made significant contributions to the understanding of the Milky Way and a pioneer in the field of radio astronomy. His New York Times obituary called him “one of the century’s foremost explorers of the universe;” the European Space Agency website describes him as, “one of the greatest astronomers of the 20th century,” and states that he “revolutionised astronomy through his ground-breaking discoveries.” In 1955, Oort’s name appeared in Life Magazine’s list of the 100 most famous living people. He has been described as “putting the Netherlands in the forefront of postwar astronomy.”
It’s a Southern Sky Costellation – that can be seen in the Northern Sky
It can be seen with the naked eye in the southern sky, low on the horizon – in the early hours of the morning in August.
Microscopium is a small constellation in the southern sky, defined in the 18th century by Nicolas Louis de Lacaille. Its brightest star is Gamma Microscopii of apparent magnitude 4.68, actually a yellow giant located around 381 light-years distant. Two star systems—WASP-7 and HD 205739—have been found to have planets, while another—AU Microscopii—has a debris disk.
The stars that now comprise Microscopium may formerly have belonged to the hind feet of Sagittarius. However, this is uncertain as, while its stars seem to be referred to by Al-Sufi as having been seen by Ptolemy, Al-Sufi does not specify their exact positions.
Its name is Latin for microscope; it was invented by Lacaille to commemorate the compound microscope. Its stars are very faint and hardly visible from most of the non-tropical northern hemisphere.
The brightest star is Gamma Microscopii, which has an apparent (visual) magnitude of 4.68. It is a yellow giant of spectral type G6III. Lying 381 light years away, It depicts the eyepiece of the microscope. Alpha Microscopii is also a yellow giant, though in this case a variable star, which ranges between apparent magnitudes 4.88 and 4.94. It is of spectral type G7III. Alpha has a 10th magnitude companion, visible in small telescopes. Epsilon Microscopii lies 165 light years away, and is a blue-white main sequence star of apparent magnitude 4.7, and spectral type A1V. Theta1 and Theta2 Microscopii make up a wide double whose components are splittable to the naked eye. Both are white A-class magnetic spectrum variable stars with strong metallic lines, similar to Cor Caroli. They mark the constellation’s specimen slide.
Many notable objects are too faint to be seen with the naked eye. AX Microscopii, better known as Lacaille 8760, is a red dwarf which lies only 12.9 light years from our solar system. HD 205739 has a jupiter-sized planet. WASP-7 is a star of magnitude 9.54 which has been discovered to have an exoplanet WASP-7b, while AU Microscopii is a young star which appears to be a solar system in the making with a debris disk. BO Microscopii is a rapidly rotating star, and PSR J2144-3933 is an unusual pulsar with an unusually long rotation period.
Cecilia Helena Payne-Gaposchkin (May 10, 1900 – December 7, 1979) was a British-American astronomer and astrophysicist who, in 1925, proposed in her Ph.D. thesis an explanation for the composition of stars in terms of the relative abundances of hydrogen and helium.
Shapley persuaded Payne to write a doctoral dissertation, and so in 1925 she became the first person to earn a Ph.D. in astronomy from Radcliffe College (now part of Harvard). Her thesis was “Stellar Atmospheres, A Contribution to the Observational Study of High Temperature in the Reversing Layers of Stars”. Astronomer Otto Struve called it “undoubtedly the most brilliant Ph.D. thesis ever written in astronomy”.
Payne was able to accurately relate the spectral classes of stars to their actual temperatures by applying the ionization theory developed by Indian physicist Meghnad Saha. She showed that the great variation in stellar absorption lines was due to differing amounts of ionization at different temperatures, not to different amounts of elements. She correctly suggested that silicon, carbon, and other common metals seen in the Sun’s spectrum were found in about the same relative amounts as on Earth, but that helium and particularly hydrogen were vastly more abundant (for hydrogen, by a factor of about one million). Her thesis established that hydrogen was the overwhelming constituent of the stars (see Metallicity), and thus the most abundant element in the Universe.
When Payne’s dissertation was reviewed, astronomer Henry Norris Russell dissuaded her from concluding that the composition of the Sun is different from that of the Earth, contradicting the accepted wisdom at the time. However, he changed his mind four years later after deriving the same result by different means. After Payne was proven correct, Russell was often given the credit, although he himself acknowledged her work in his paper.
Cecilia Helena Payne was one of three children born in Wendover, England to Emma Leonora Helena (née Pertz) and Edward John Payne, a London barrister, historian and accomplished musician. Her mother came from a Prussian family and had two distinguished uncles, historian Georg Heinrich Pertz and the Swedenborgian writer James John Garth Wilkinson. Cecilia Payne’s father died when she was four years old, forcing her mother to raise the family on her own.
She attended St Paul’s Girls’ School. Her mother did not choose to spend money on her college education, but only on her brother’s. In 1919, she won a scholarship to Newnham College, Cambridge University, where she read botany, physics, and chemistry. Here, she attended a lecture by Arthur Eddington on his 1919 expedition to the island of Principe in the Gulf of Guinea off the west coast of Africa to observe and photograph the stars near a solar eclipse as a test of Einstein‘s general theory of relativity. This sparked her interest in astronomy. She completed her studies, but was not awarded a degree because of her sex; Cambridge did not grant degrees to women until 1948.
Cecilia Payne realized that her only career option in the U.K. was to become a teacher, so she looked for grants that would enable her to move to the United States. After meeting Harlow Shapley, the Director of the Harvard College Observatory, who had just begun a graduate program in astronomy, she left England in 1923. This was made possible by a fellowship to encourage women to study at the Observatory. The first student on the fellowship was Adelaide Ames (1922) and the second was Payne.
After her doctorate, Payne studied stars of high luminosity in order to understand the structure of the Milky Way. Later she surveyed all the stars brighter than the tenth magnitude. She then studied variable stars, making over 1,250,000 observations with her assistants. This work later was extended to the Magellanic Clouds, adding a further 2,000,000 observations of variable stars. These data were used to determine the paths of stellar evolution. Her observations and analysis, with her husband, of variable stars laid the basis for all subsequent work on them.
Payne-Gaposchkin remained scientifically active throughout her life, spending her entire academic career at Harvard. At first, she had no official position, merely serving as a technical assistant to Shapley from 1927 to 1938. At one point she considered leaving Harvard because of her low status and poor salary. However, Shapley made efforts to improve her position, and in 1938 she was given the title of “Astronomer”. She later asked to have this title changed to Phillips Astronomer. None of the courses she taught at Harvard were recorded in the catalogue until 1945.
When Donald Menzel became Director of the Harvard College Observatory in 1954, he tried to improve her appointment, and in 1956 she became the first woman to be promoted to full professor from within the faculty at Harvard’s Faculty of Arts and Sciences. Later, with her appointment to the Chair of the Department of Astronomy, she also became the first woman to head a department at Harvard.
Her students included Helen Sawyer Hogg, Joseph Ashbrook, Frank Drake and Paul W. Hodge, who all made important contributions to astronomy. She also supervised Frank Kameny, who became a prominent advocate of gay rights.
Payne-Gaposchkin retired from active teaching in 1966 and was subsequently appointed Emeritus Professor of Harvard. She continued her research as a member of staff at the Smithsonian Astrophysical Observatory.
Staring at Cepheus In 2015
The Latest I Have Spotted
The last constellation for my naked eye to see is Cepheus. This has been quite a productive few weeks, I have added a handful of naked-eye view’s to my constellation list. I have also seen Saturn. Very pleased at that – just a shame you can’t see the rings without a telescope!
Cepheus is a constellation in the northern sky. It is named after Cepheus, King of Aethiopia in Greek mythology. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern constellations. Cepheus was the King of Aethiopia. He was married to Cassiopeia and was the father of Andromeda, both of whom are immortalized as modern day constellations along with Cepheus.
Cepheus son of Agenor is the more well-known Cepheus and the grandson of the other Cepheus. He is featured in the Perseus legend as the husband of lovely Cassiopeia and father of Princess Andromeda, and whose brother Phineus expected to marry Andromeda. When Poseidon sent the sea monster Cetus to attack Aethiopia after his wife boasted that Andromeda was more beautiful than the Nereids, Cepheus and Cassiopeia consulted with a wise oracle who told them to sacrifice Andromeda to Cetus. Cepheus and Cassiopeia had Andromeda chained to a rock near the ocean so that Cetus could devour her. Andromeda was saved from this fate when Perseus arrived and killed Cetus. Cepheus and Cassiopeia allowed Perseus to become Andromeda’s husband after he used Medusa‘s head to turn Phineus and his men to stone.
Cepheus was later made into the constellation Cepheus.
More Astro Info:
Mythology of the constellation Pegasus
The white, winged horse Pegasus was the offspring of Poseidon and the Gorgon , Medusa, springing from the latter’s neck when she was killed by Perseus. He immediately flew to Mount Helicon and struck the ground with his hoof. The resulting stream which flowed from the spot he had pawed became sacred to the Muses. Some time later Pegasus was to help Perseus to rescue Andromeda from the dreadful sea monster Cetus.
Bellerophon, the grandson of Sisyphus (a selfish man punished by the Gods for his arrogance by being forced to continually push an enormous boulder to the top of a hill, only for it to roll back down just as the goal seemed within reach) was also greatly aided by Pegasus when undertaking several dangerous missions, including his fight against the Chimaera, the three-headed monstrous female. However, the success of this and other missions turned Bellerophon’s head and he, too, became arrogant. So much so, that although a mere mortal, he forced Pegasus to fly him to Mount Olympus, the home of the Gods. Zeus , greatly annoyed at Bellerophon’s presumption that he was worthy to be in such august company, sent an insect to bite Pegasus on his flank, causing him to rear up and throw Bellerophon to the ground. He was then dispatched back to earth, and ended his days a sad and lonely figure, blind and lame. For Pegasus, however, there was the reward of a place in the stables on Mount Olympus, and the opportunity to carry around Zeus’s thunderbolts.
Mythology of the constellation Boötes
BOOTES, The Hunter has since early times been associated with country pursuits – as hunter, ploughman or herdsman. In Homer’s Odyssey he is referred to as Wagoner or Driver of the Wain. However, since the seventeenth century the figure has been associated with the hunting dogs (Canes Venatici) charted by Helvelius.
In Greek legend, Bootes is seen as representing Icarius, an Athenian who was taught the secret of winemaking by the god Dionysius. Icarius then allowed some peasants to sample his produce, but his kindness back-fired. The men became extremely drunk and were convinced that they had been poisoned, so they killed Icarius and buried him. His daughter Erigone and was so overcome with grief when she found his body that she hanged herself. Zeus transferred her to the heavens as Virgo, Icarius became Bootes, and Maera, the dog who had led Erigone to her father’s grave, became one of the dogs of Canes Venatici.
Mythology of the constellation Aquarius
This is the eleventh zodiacal sign and one which has always been connected with water. To the Babylonians it represented an overflowing urn, and they associated this with the heavy rains which fell in their eleventh month, whilst the Egyptians saw the constellation as Hapi, the god of the Nile.
Greek legend, however, tells of Ganymede, an exceptionally handsome, young prince of Troy. He was spotted by Zeus, who immediately decided that he would make a perfect cup-bearer. The story then differs – one version telling how Zeus sent his pet eagle, Aquila, to carry Ganymede to Olympus, another that it was Zeus, himself, disguised as an eagle, who swept up the youth and carried him to the home of the gods. In either case, once Ganymede arrived, he had to contend with the wrath of Hera, wife of Zeus. She was annoyed on two counts – firstly, that her husband should have such strong feelings for a mere boy and, secondly, that Ganymede was to occupy the favoured position previously held by her own daughter Hebe, goddess of youth. But Zeus was not to be thwarted and Ganymede, often riding on Aquila and always carrying the golden cup, accompanied the great god on his travels, impressing him with his kindness. This was made manifest when, realising how in need of water the people on earth were, he pleaded with Zeus to be allowed to help them and was given permission to send down rain. Eventually he was glorified as Aquarius, god of rain, and placed amongst the stars.
Mythology of the constellation Camelopardalis
CAMELOPARDALIS, The Giraffe. is said to represent the Biblical camel which carried Rebecca to Isaac. However, historians are divided as to the inventor of this modern constellation. Some say that Dutchman Petrus Plancius first charted Camelopardalis in 1613, it later being included in Jakob Bartsch’s book on the constellations, whilst others suggest that Bartsch, himself, invented the constellation in 1624.
Mythology of the constellation Coma Berenices
The constellation COMA BERENICES represents the beautiful hair of Queen Berenice of Egypt. She was so concerned for the safety of her husband Ptolemy III when he went off to war, that she vowed to cut off her glorious long hair as a sacrifice to Venus, should he be spared. When he eventually returned safely home, she kept her promise, and Zeus placed her beautiful hair in the heavens to shine among the stars.
Another account suggests that this constellation represents Thisbe’s veil (Legend of Leo).
Mythology of the constellation Cygnus
Many and varied are the myths relating to the naming of the constellation Cygnus, The Swan, some dating back to pre-Greek times, when it was thought that this particular group of stars represented the huge bird “Roc” from the tales of Sinbad the Sailor.
Amongst the many Greek myths relating to Cygnus are that it was once the pet bird of Cassiopeia, or that the constellation represents the murdered Orpheus who was changed into a swan after being murdered by the Thracian women. Two further possibilities are that it was named after either Cionus, Son of Neptune, who was changed into a swan and transported to the heavens by his father in order to prevent him from being smothered by Achilles, or after Cygnus, who tried to save his friend Phaeton, when the latter was struck by one of Zeus’s thunderbolts and hurled into the River Eridanus following his unsuccessful attempt to guide the Sun’s chariot across the heavens.
But possibly the most well known of myths surrounding this constellation is that it represents Zeus in the story of Leda and the swan, Leda being the very beautiful wife of King Tyndareus, of Sparta.
Zeus, noted for his affairs with mortal women, fell in love with Leda and changed himself into a swan in order to seduce her. She produced an egg from which emerged Castor, the mortal son of her husband, and Polydeuces (Pollux), immortal son of Zeus.
VY CMa – Red Hypergiant
It is around 3,900 light-years from Earth. VY CMa is a single star categorized as a semiregular variable and has an estimated period of 2,000 days. It has an average density of 5 to 10 mg/m3. If placed at the center of the Solar System, VY Canis Majoris’s surface would extend beyond the orbit of Jupiter, although there is still considerable variation in estimates of the radius, with some making it larger than the orbit of Saturn.