NOV - This Month's Astronomy History

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This Month in the History of Astronomy - November

Birthdays || Discoveries

Nov 1, 1919 - Hermann Bondi, cosmologist, co-inventor of the Steady State theory of the cosmos.
Bondi was born in Vienna, Austria, where experience at a young age with the orthodox Jewish community left him with strong anti-religious views, seeing it as associated with repression and intolerance, even though he himself was technically of Jewish descent; he described himself as "direct hostile" to religion.
When he was sixteen the famous British astronomer Sir Arthur Eddington was visiting Vienna and Bondi was able to meet him. Deciding that Austria was too much of a scientific backwater, Bondi applied to and got admitted to university in Cambridge the next year. As a foreign student, when Austria became part of the pan-German Reich, Bondi was interned for fifteen months (1940-41), but it was in Quebec, Canada. His parents immigrated to New York, and even got Einstein to intervene on his behalf, but he was not allowed to cross into the US. Thus he became a British citizen and not an American.
After release from internment, he returned to academia in Great Britain before joining Fred Hoyle's military radar development group (magnetrons, specifically), where he worked with Tommy Gold [see May 22]. Bondi and Gold developed a cosmological theory which was in many ways quite distinct from Hoyle's, though today the three together are remembered as the originators of the Steady State theory during the 1947-53 period, even though cosmologies with somewhat similar aspects had been around for decades in Great Britain, involving names such as Eddington, Jeans, Millikan, Nernst, and Milne.
Nov 2, 1885 - Harlow Shapley, American pioneer in determining distances to stars, clusters, and the center of the Milky Way; Harvard College Observatory director for more than three decades.
Early in his career (1911-14) he was Henry Norris Russell's assistant and Ph.D. student at Princeton, working on eclipsing binary stars. Nearly 10,000 photo-polarimeter measurements on some 90 such systems with the 23" refractor led to great advances in the understanding of very close double stars. He was also able to show that Cepheid variable stars are pulsating single stars, not double stars.

After seven subsequent years at the Mount Wilson Observatory, where he'd been hired by George Hale, he moved to Harvard as the Director, replacing the recently deceased Edward Pickering (who'd been in charge since before Shapley was born). At Mount Wilson he began studying the variable stars in globular star clusters known as RR Lyrae variables (after the prototype). With these he was able to determine distances to the clusters, more than 90 of them, showing that the Sun wasn't at the center of a flattened star system some 10,000 light years in diameter (as Kapteyn's 1923 model had it), but that the center of the system of globular star clusters was some 60,000 light years away -- high by ~2x because he didn't take interstellar extinction and its dimming of starlight into account, which makes things look farther away than they are -- in the direction of what we now take as being the center of the Milky Way galaxy in Sagittarius.
Part I of a two-part 1966 interview, the first third or half of which reads like an advertisement for when America was a land of opportunity.
Nov 5, 1906 - Fred Whipple, developer of the dirty snowball model for comets. After an education at UCLA, a teaching fellowship at UC/Berkeley, and a Ph.D. at Lick Observatory (1931), Whipple moved to Harvard and became a full professor by 1950, a post he held until retirement 27 years later. During WWII he worked on radar for the Office of Scientific Research and Development. He was also Director of the Smithsonian Astrophysical Observatory from 1955 to 1973. Whipple discovered six new comets, and worked on a number of related subjects, from the connection between comets and meteors, to the determination of cometary orbits, and the formation of solar systems.
Nov 8, 1656 - Edmund Halley, multi-talented English scientist best known for first determining the orbit of the comet which bears his name, and for encouraging Isaac Newton to publish his famous work on calculus, gravity, and the laws of motion. He also discovered (1718) that some of the "fixed stars" actually had what's called "proper motion", meaning they're not stationary ("fixed") after all.
Nov 9, 1934 - Carl Sagan, U.S. astronomer, planetologist, exobiologist, and popularizer of science and astronomy during the Space Age, (and novelist) and arguably the most famous and well known scientist of about the last third of the twentieth century.
Nov 10, 1843 - The Cincinnati Observatory, the first professional observatory in the U.S., is dedicated and its cornerstone laid by former President John Quincy Adams. It featured a 12" refractor and went into astronomical operation in January 1845.
Nov 11, 1875 - Vesto Slipher, pioneer American observer who was the first to photograph galaxy spectra and measure their redshifts, which led to the discovery of the expansion of the universe by Hubble. By 1925 Slipher had compiled redshifts for 44 galaxies, which Hubble added distance determinations to, leading to the development of his famed distance-redshift relationship (Hubble's Law), as well as the idea of an expanding universe.
Slipher spent his career at the Lowell Observatory, where he was acting or actual Director from 1916 until retiring in 1952. He was the chairman of the Flagstaff school board in 1925.
Slipher was behind the search for Pluto which led to its discovery by Clyde Tombaugh in 1930. His other work centered on determining the rotation rate of the planets, and his result for featureless Venus, based on spectral Doppler shifts, is basically the modern value. This same technique is used to determine the rotation curves (and masses) of galaxies. For all the planets outward from Venus except Neptune he had a rotation rate he'd measured. His initial interest in measuring galaxy spectra, around 1907, was actually based on the hypothesis that they were possibly planet-forming nebulae.
Slipher also worked on gaseous nebulae in the Milky Way, the interstellar calcium absorption lines in stellar spectra, and was the first to show that the nebulosity around the Pleiades star cluster was reflected starlight, due to its hot, B-type stellar spectrum -- same as its brightest stars.
Nov 13, 1831 - James Clerk Maxwell, English pioneer theoretician in electromagnetism and the nature of light.
Nov 15, 1738 - William Herschel, British astronomer and musician, the discoverer of the planet Uranus (1781), the motion of the Sun in the Milky Way (1785), Castor's binary companion (1804, and in accordance with Kepler's Laws), and infrared radiation. Herschel also discovered many clusters, nebulae, and galaxies in the course of surveying the night sky and compiling catalogues whose basic data is still in use today.
Nov 16, 1717 - Jean-Baptiste d'Alembert, French mathematician, physicist, and theoretical astronomer who worked out an early theory of refraction (1740) from considering models of fluids, invented the field of differential equations, and was the first, along with Lagrange and Laplace, to apply principles of calculus to celestial mechanics.
Nov 18, 1897 - Patrick Blackett, British physicist who won the 1948 Nobel Prize for the invention of the cloud chamber, with which he obtained the first photograph (1924) of an atomic transmutation -- nitrogen bombarded with alpha particles turning into oxygen.
By 1932 his cloud chamber was automatically recording cosmic rays, and the next year he confirmed the existence of the positron (the anti-electron or positive electron, e⁺). Several years later his cosmic ray studies turned up the first 'strange' particles, such as the hyperon, with lifetimes of only 10^-10 seconds; moving at almost the speed of light, a particle such as this would only travel an inch before decaying into other particles. Blackett also confirmed Einstein's famous E=mc² equation by being the first to observe partice-antiparticle pair creation by energetic cosmic gamma rays.
Nov 18, 1915 - General Relativity. On this date Einstein addressed the Prussian Academy of Sciences with his new, comprehensive theory and announced the solution to the mystery of the perihelion advance of Mercury's orbit, the result of a minute amount of spacetime curvature so close to the Sun.
Nov 20, 1889 - Edwin Hubble, American astronomer who first identified Cepheid variables in M31, establishing the extragalactic nature of the spiral nebulae (galaxies). Building on work by Carl Wirtz, and with Slipher's redshifts (see above), Hubble established the velocity-distance relation for galaxies (Hubble's Law) which demonstrates the universe's expansion.
Nov 25, 1858 - Julius Scheiner, German astronomer and early astro-photographer. He started out as an assistant at the observatory in Potsdam in 1887, and became its observer-in-chief in 1898, three years after being appointed to the chair of astrophysics at the University of Berlin.
Scheiner developed the first system for measuring the sensitivity of photographic emulsions (1894), and made the first known spectrum of the Andromeda Galaxy (M31) in January, 1899, published shortly thereafter in the then 3-4 year old Astrophysical Journal.
Nov 29, 1913 - Benjamin Markarian, Armenian astronomer who did his thesis under Viktor Ambartsumian, started out studying the spectra of white dwarfs and stars in open clusters, but was tasked, starting in 1965 by the famed Byurakan Observatory director, with finding faint blue galaxies that had strong ultraviolet emission. Using the 1-meter Schmidt telescope, which was the largest such telescope in the world to have an objective prism, he searched spectra on some 2,000 plates -- each with more than 10,000 objects -- and found 1,500 such galaxies by the time the survey was completed in 1978. Today such active galaxies are known by their Markarian numbers, though a significant fraction are quasars and there are about a dozen which are simply giant HII regions inside of galaxies.

Discoveries and other firsts

Halton C.
- Chip - Arp, from a 1975 interview

Nov 1, 1977 - Charles Kowal discovers Chiron, the first of a population of smallish icy objects residing in the outer solar system.
Nov 2, 1917 - First light for the Mt. Wilson 100" telescope.
Nov 3, 1955 - A woman in the U.S. is struck by a falling meteorite, one of the few well-documented instances of this having happened.
Nov 3, 1957 - First Earth life in orbit: the "Muttnik" dog Laika is launched aboard the USSR's Sputnik 2 and dies in orbit. Sputnik 2 stayed up another 5 months before burning up on re-enty Apr 14, 1958.
BBC World Service Radio's "Witness History" 10 minute piece on Laika
Nov 4, 2019 - The first star ever detected with a velocity much greater than the Milky Way's escape velocity, which has been generally thought to lie at ~450-600 km/sec in the Sun's vicinity. The star is believed to be in the process of being flung out of the galaxy by a close encounter with the massive black hole thought to be at its center nearly five million years ago -- is announced by an Australian team using the 3.9-meter telescope at the Siding Spring Observatory. From the abstract for their paper:

We present the serendipitous discovery of the fastest main-sequence hyper-velocity star (HVS) by the Southern Stellar Stream Spectroscopic Survey (S5). The star S5-HVS1 is a ∼2.35 M⊙ A-type star located at a distance of ∼9 kpc from the Sun and has a heliocentric radial velocity of 1017 ± 2.7 kms⁻¹ without any signature of velocity variability. The current 3D velocity of the star in the Galactic frame is 1755 ± 50 kms⁻¹. When integrated backwards in time, the orbit of the star points unambiguously to the Galactic Centre, implying that S5-HVS1 was kicked away from Sgr A* with a velocity of ∼1800 kms⁻¹ and travelled for 4.8 Myr to its current location. This is so far the only HVS confidently associated with the Galactic Centre. S5-HVS1 is also the first hyper-velocity star to provide constraints on the geometry and kinematics of the Galaxy, such as the Solar motion Vy,⊙ = 246.1 ± 5.3 kms⁻¹ or position R0 = 8.12 ± 0.23 kpc.
S5-HVS1 is the third-fastest star on record, the two others having been accelerated by supernovae explosions. It will be nearly 100 million years before S5-HVS1 leaves the Milky Way, even at this high a velocity.
Nov 4, 2023 - Scott Sheppard (Carnegie Science) discovers S/2023 U1, the first new moon discovered orbiting Uranus in more than 20 years, with the Magellan telescope at Las Campanas Observatory in Chile. A post-discovery check of images taken in 2021 with both the Magellan and Subaru telescopes showed the moon and helped determine its orbital period of 680 days.
At only ~5 miles across, the orbit of S/2023 U1 puts it in a group with two larger and better-known moons of Uranus, Caliban and Stephano; it's thought all three originated from the break-up of a single larger body.
Nov 5, 2018 - The Voyager 2 spacecraft reaches the heliopause and makes the transition into interstellar space, its plasma detector registering a sharp decrease in the speed of solar wind particles. Around the same time it saw a sharp increase in the number of cosmic ray particles, as well as an increase in the ambient magnetic field. Voyager 1 crossed the heliopause into interstellar space more than half a dozen years earlier (see Aug 25, 2012) but its plasma detector had failed back in 1980 so the transition was not as distinct. Both spacecraft are expected to continue operating and sending back data for another 5-10 years.
Nov 6, 1572 - Tycho Brahe records a bright new star -- now known to have been a supernova -- in Cassiopeia, "visible" today only at very long, radio wavelengths. The SN was visible to the unaided eye -- the telescope not having been invented yet -- for 16 months (until March 1574), and was visible during the daytime, reaching a maximum brightness estimated at mag -4.0 (almost as bright as Venus). In 1934 Walter Baade re-analyzed Tycho's data and concluded the light curve was that of a Type I supernova.
Nov 7, 1492 - The Ensisheim meteorite fall occurred in the Alsace region of eastern France shortly before noon, was witnessed by thousands of people, heard for many dozens of miles around, and left a crater a meter deep. Of the original estimated mass of ~135 kg (300 pounds), the largest surviving piece weighs about 56 kg (125 pounds). This was the earliest known widely witnessed meteorite fall in Europe which has been preserved.
Nov 7, 1631 - French astronomer Pierre Gassendi becomes the first to witness a transit of Mercury (across the Sun).
Nov 8, 1985 - Stephen Edberg, then serving as the Coordinator for Amateur Observations at NASA's Jet Propulsion Laboratory, and Charles Morris were the first to observe Halley's Comet with the naked eye at its 1986 apparition.
Nov 11-12, 1799 (79?) - Swedish astronomer Peter Wargentin observes the brightest maximum ever recorded for the famed variable star Mira (ο Ceti) at magnitude 1.2.
Nov 12, 1782 - Eighteen year-old John Goodricke of York, England, begins the first systematic observations of the star Algol (β Persei), by chance during one of its eclipses. He was working off a list of suspected variable stars put together by friend and mentor Edward Pigott, who had been comparing Flamsteed's newest star maps with older maps going back to antiquity, looking for stars that might have changed in brightness. At the time, only Mira (ο Ceti), with an eleven month period, was known to be variable, and for centuries the stars had been believed to be fixed and unvarying.
Observing every clear night possible, Goodricke and Pigott were not able to see another eclipse until Dec 28th. They soon determined the dip in brightness from second magnitude to fourth or fifth magnitude lasted seven hours and occurred every 2 days 20 hours and 45 seconds.
Both Goodricke and Pigott interpreted the light curve as being due to an eclipsing planet in orbit about the star, and roughly half its size, not a companion star, but after the observation was confirmed by William Herschel, in May, 1783, a controversey arose: spots on the sun had been known for 175 years, but no other planetary systems or binary stars were definitively known, so the conservative view held that Algol was a heavily spotted star, light on one side and dark on the other, which rotated. Goodricke was eventually persuaded that it must be so. It would be more than a century before his original explanation about the eclipsing nature of the system was confirmed by spectroscopy.
The next year, 1784, Goodricke and Pigott turned up three more variable stars: β Lyrae (another eclipsing system) and the first two Cepheid variables, δ Cephei (the prototype) and η Aquilæ.
Unfortunately for both himself and astronomy, Goodricke, who was deaf and suffered from other ailments, would only live until Apr 20, 1786, just two weeks after being elected to membership in the Royal Society. Pigott would go on to discover two more variable stars, R Coronae Borealis and R Scutti, thus establishing the reality, with John Goodricke, of a new class of stars of variable brightness.
Nov 12, 1949 -The first scientific observations were made with the Palomar 5-meter (200-inch) telescope.
The telescope, the first plans for which originated twenty years earlier, had been completed and formally dedicated some sixteen months earlier, but observatory director Ira S. Bowen wouldn't okay the telescope for scientific use until everything with it was in tip-top shape, because he knew once it was in general use it would be near-impossible to take it off-line to work on the remaining small problems.
Chief among these was a slight turned-up edge on the mirror. Because the supports for the mirror on its back went out only to within 20" of its edge, the turn-up was actually intentional, with the idea that these unsupported edges would sag slightly in operation, cancelling out the departure from a perfect figure. As it turned out, the mirror was stiffer than anticipated and had to be removed from the telescope and worked on on the floor of the dome with fine abrasives to take the edges down the needed amount.
Nov 12, 1980 - Voyager 1 makes its closest approach to Saturn before heading out of the solar system.
Nov 12, 2014 -The European Space Agency's Rosetta mission, launched on 2 March 2004, and in orbit around the two-lobed comet 67P/Churyumov–Gerasimenko since Sep 10th, deploys its Philae lander to the surface, the first spacecraft to land on a comet nucleus. Because the surface gravity of the comet is only 1/10,000 that of Earth, the spacecraft had mechanisms to try and attach itself, but these failed and the lander bounced twice before apparently falling into a crack or crevice. Its solar panels inoperable, its battery power only lasted three days. Before losing contact, the Ptolemy instruments on the Philae's lander revealed sixteen organic compounds, four of which (acetamide, acetone, methyl isocyanate and propionaldehyde) were seen for the first time on a comet.
Nov 12/13, 1833 - The night of the Great Meteor Shower (Leonid). On the morning of 11/17/1967 a rate of 150,000/hour for ~20 minutes was reported -- the last time there's been such a high rate for the Leonid shower.
Nov 13, 1970 - First ever detection of a neutrino on earth:

The neutrino comes in, invisibly, from about the 4 o'clock direction, and hits the proton (hydrogen nucleus) which is already moving in the 11 o'clock direction because of its thermal motion; as part of a neutral hydrogen atom (or molecule) it is not previously visible. This bubble chamber photo also demonstrates another aspect of particle physics: fermions (the two mesons) are always created in pairs.
Nov 13, 1971 - The U.S.'s Mariner 9 becomes the first spaceprobe to orbit Mars. 7,000+ images, some of which showed features like those on earth associated with running water, suggested that at some time in the past -- 3½-4 billion years ago is the current best estimate -- Mars had a much denser atmosphere and a warmer climate, since liquid water can't exist there now.
Nov 14, 1680 - The Great Comet of 1680, the first comet discovered with a telescope, by German astronomer Gottfried Kirch, is first seen. It was one of the brightest comets of the 17th Century, had a very long tail, and was supposedly visible even during daytime. It was used by Isaac Newton to validate Kepler's laws; there's a diagram of the comet's orbit in his famed book Principia.
The comet's orbit was essentially parabolic (period ~10,000 years) and it was a sun-grazer, with a perihelion distance about a month after discovery of only 0.0062 AU (1.33 solar radii). This means it zipped by the sun at only 1/3rd of a solar radius above the photosphere. The comet was at its brightest about 10 days after perihelion passage and was observed for another fifteen months. It is now some 8x farther away than Pluto.
Nov 14, 2003 - 90377 Sedna is discovered by Palomar's QUEST (Quasar Equatorial Survey Team) -- a mosaic of 112 CCD detectors covering a 4° x 4° field of view of the 48" Schmidt telescope -- that has discovered some 40 Kuiper Belt objects.
Nov 15, 1968 - R.B.E. Lovelace and associates observe the pulsar NP 0532 in Taurus with the 305-meter Arecibo radio telescope and determine its position to be within 10 arc-minutes of the center of the Crab Nebula (M1), the remnant of the supernova observed in 1054 A.D.
Because lower frequency radio waves are slowed a tiny bit by free electrons in the interstellar medium (trapped in the galaxy's magnetic field) between us and the pulsar, it's possible to estimate its distance from the relative delay of its pulses at one frequency relative to another. This distance was in line with estimates of the distance to M1.
Along with another pulsar previously found that was near the center of the radio source Vela X, which has a broken up shell-like or bubble appearance at visual wavelengths and had been hypothesized to perhaps be an older, larger, and more evolved supernova remnant, less than a year after the first pulsar was discovered this was the start of the idea that they were the stellar remnants of supernovae explosions, though at that time their nature was unknown and they were thought to maybe be pulsating stars of some sort rather than rotating highly magnetized neutron stars.
Nov 16, 1974 - The new surface of the giant 1000-foot radio telescope at Arecibo, Puerto Rico, is dedicated by sending a brief message in the direction of the half million or so stars in the globular cluster M13. [Full story]
Nov 17, 1970 - Luna 17 is the 1st wheeled vehicle to land on the moon. Remotely controlled, it took pictures, gathered soil samples, and made other measurements for several months.
Nov 17, 1981 - The last occultation of Sigma (σ) Sag by a planet (Venus) took place. At magnitude +2.05 and ~3½° S of the ecliptic, σ Sag is the brightest star that can be occulted by a planet outside earth's orbit, though only Mars has an inclined enough orbit to do so; this last happened Sep 3, 423.
σ Sag bore the traditional name of Nunki, which was an Assyrian or Babylonian name recovered by archaeologists. It's a part of the well-known "Teapot" asterism, at the top of the handle. It's a fairly rare B2½ spectral type main sequence star, almost eight times the mass of the sun, a rotation rate ~200x greater than the sun, and has a much fainter 10th magnitude companion some 5 arc-minutes away, making it an easy visual double star in a small telescope.
The star was one of two stars -- Antares being the other -- first visible to the Apollo 13 astronauts after they went into the shadow of the moon ~24 hours after oxygen tank #2 exploded, surrounding the spacecraft in a dense cloud of O₂ ice crystals and debris that entirely obscured their view beyond the spacecraft, seriously hampering their ability to get a good navigational fix on their direction of travel following the onset of the emergency.
Nov 18, 1989 - Launch of the COBE (COsmic Background Explorer) satellite aboard a Delta rocket into a polar, sun-synchronous orbit. By April 23, 1992, the COBE team had acquired sufficient data (~10 months) to detect and announce the anisotropy in the 3° cosmic microwave background, at the level of only one part in 100,000 of its absolute brightness, which won the Physics Nobel Prize in 2006 for Smoot and Mather, two of the mission instrument designers and principal investigators.
COBE also made important measurements and discoveries relating to the diffuse infrared background (w/DIRBE - the Diffuse InfraRed Background Experiment), which showed that the interplanetary dust responsible for the zodiacal light is likely of asteroidal (and/or cometary) origin. These measurement also determined that the sun's orbit around the Milky Way galaxy is such that the sun is currently 15.6 parsecs (51 light years) above the midplane of the disk. Stars like the sun in nearly circular orbits around the galaxy do not follow Keplerian orbits, and are thought to oscillate up and down through the midplane several times per orbit.
Nov 19, 1816 - Though he did not write up the report until 1820, Carl Wolfgang Benjamin Goldschmidt calls attention to the "shadow bands" visible just before and after totality at some total solar eclipses. The earliest known record of these goes back to the Volospa, part of the old German poetic edda from the 9th century.
Nov 19, 1962 - The first interplanetary radio message, the so-called Mir Message, was sent from a radar dish in the Ukraine (then part of the Soviet Union) towards Venus, in Morse code.
Nov 20, 2010 - The launch of NASA's NanoSail-D2, a low Earth orbit satellite which tested solar sail technology by unfurling one with an area of 10 square meters, on Jan 20, 2011. The satellite re-entered the atmosphere on Sep 17, 2011.
Nov 21, 1862 -- Warren de la Rue makes the first photograph of a solar eclipse (partial), but had to go all the way to Antarctica to do it.
Nov 21, 2009 - The Cassini spacecraft first sees erupting geysers on Saturn's moon Enceladus.
Nov 23, 1885 - The first photograph of a meteor shower is made.
Nov 23, 1949 - Walter Baade images the area around SN 1572 (Tycho's Supernova) with the new 200-inch telescope on Mount Palomar. His red sensitive plates showed nebulosity on the E edge of where the remnant was expected to be (based on its not very precise radio position), but he didn't report its detection after concluding what he saw was too far away in angular distance to be related to Tycho's Star.
Credit for the discovery of the remnant, in 1952, thus goes to Hanbury Brown and Hazard at the Jodrell Bank radio observatory. 3C 10, as its radio catalogue name goes, is the second brightest radio source in the constellation Cassiopeiae, and Cas A (the brightest) is the brightest radio source in the sky outside the solar system. Almost all the supernovae remnants in the Milky Way (50+) have been discovered by their radio emissions.
Nov 23, 1977 - Meteosat 1 becomes the first satellite put into orbit by the European Space Agency (ESA).
Nov 26, 1965 - First French satellite launch -- Asterix 1.
Nov 26, 2018 - The landing of NASA's InSight spacecraft in Elysium Planita on Mars, the first seismometer to operate on the planet since the Viking landers attempted similar operations in 1976, albeit with several orders of magnitude less sensitivity.
Data collected from this equatorial site in the first 3-3½ years casts doubt on the existence of extensive sub-surface deposits of water ice (permafrost), long hypothesized as being a possibile location for all the remnant water thought to have existed on Mars way back when it was warmer and wetter ~3 billion years ago, at least at lower latitudes. No evidence was found for water or ice in the sedimentary layers down to 300 m (1,000 ft) beneath the lander.
Nov 26, 2019 - The red super-giant star Betelgeuse drops below magnitude 1.0, dimming to magnitude 1.7 by early February 2020. The star, known to be irregularly variable since at least the time of John Herschel (c.1840), had briefly dipped as low as 1.2, in 1927 and 1941, so this is the dimmest it's been in historical times.
Experts at Vanderbilt University who had monitored the star for decades say Betelgeuse hit a minimum visual magnitude of 1.614 ±0.008 from Feb 7-13, 2020, before returning over the next several weeks to a more normal brightness around magnitude ½. They say the dimming was a confluence of a 425-day cycle and a 5.9-year cycle. Infrared observers say the star's brightness in the IR has remained rock constant over the last five decades.
Observation in the ultraviolet by NASA's Hubble Space Telescope indicated an immense amount of hot material (more mass than the Moon) was ejected into space by the star, at a velocity of 90 km/sec, forming a dust cloud when it cooled and elements like carbon condensed into grains that blocked starlight coming from the star's surface. This would essentially be over-shoot from the upwelling of a large convection cell originating deeper within the star. The resulting dust cloud blocked light from about a quarter of the star's surface. Observations made with NASA's Solar TErrestrial RElations Observatory (STEREO) show that Betelgeuse dimmed again, though not as dramatically, from mid-May to mid-July 2020.
The re-adjustment in the star's interior seems to have completely quelled the 425-day variabilty cycle since The Great Dimming, as it's now being called.
Nov 27, 1885 - The first known photograph of a meteor, taken by Austro-Hungarian astronomer Ladislaus Weinek during the Andromedid shower, which showed spectacular displays of several thousand meteors per hour in both 1872 and 1885, with some estimates ranging as high as 20,000 per hour.
The shower is associated with Comet Biela/3D, the third periodic comet to be discovered (on Feb 26, 1826), after Halley's and Encke's comets. It was then linked by Gambart to a comet seen in 1805. The great mathematician and physicist Gauss, with the improved orbit, then linked it to a 1772 comet seen by Montaigne and Messier. It was the first comet seen to fission into several pieces, in 1845 at the Yale Observatory. The largest surviving fragment was last seen in 1852, and was thus the first comet to acquire the "D" designation, for "lost" (or "dead").
Though the Andromedid shower has been sparse or nearly defunct since the late nineteenth century, it is thought to consist of several streams, and predictions pop up occasionally that one of these will again become active at the rate of ~200 meteors/hour in, say, 2023.
Nov 27, 1971 - The Soviet Mars-2 spacecraft becomes the first manmade object to reach (& hit) Mars.
Nov 29, 1743 - The Great Comet of 1744 (C/1743 X1) is discovered by Jan de Munck in the Netherlands. It reached perihelion Mar 1, 1744, at 0.22 AU from the sun and its intrinsic brightness is thought to have made it the sixth brightest comet in recorded history, becoming as bright as Venus and being naked eye visible during the daytime. A week or 10 days after perihelion it famously developed a fan shaped tail with six separate parts, as it moved south and became visible only from the Southern Hemisphere, where the tail(s) is said to have spanned 90°.
The comet had a big influence on the then 13 year-old Charles Messier (along with an annular solar eclipse 4 years later) becoming an astronomer who discovered 13 comets, his famous list of bright nebulous and non-stellar objects being compiled as an aid in his comet hunting.
Nov 29, 1961 - After 1,250 hours of training, the "astrochimp" Enos becomes the first living creature put into orbit by the U.S., aboard Mercury-Atlas 5. The mission lasted 3 hours, 21 minutes -- about 2½ orbits -- before parachuting down to the Atlantic Ocean. This test launch paved the way for the U.S.'s first manned orbital flight three months later.
Nov 29, 1967 - First Australian satellite launch -- Wresat 1.
Nov 30, 3340 B.C. - Likely the first known recorded total solar eclipse. This is based on three stone monuments near Loughcrew, Ireland, with spiral petroglyphs carved into them. The archeological evidence is consistent with these dating from the time when modern eclipse calculations show there was one in the area on this date. Nearby there is a mass grave with the charred bones of about four dozen people, though it's not clear if this is in any way connect with the stone markers and/or an eclipse.
Nov 30, 1787 - The 10th magnitude satellite galaxy to the Andromeda Galaxy now known as NGC 185 is first noted by William Herschel, who cataloged it as "H II.707".
This was during the period when Herschel was most intensely surveying the skies for non-stellar objects using two 20 foot focal length telescopes, one with a 12" aperture, the other 18.7". These had been made possible by funding from King George III following Herschel's discovery of the planet Uranus in 1781, who made him "The King's Astronomer" the following year. Herschel not only constructed these telescopes, but several dozen others that he sold and made money from.
During this time (1783-90) Herschel observed some 2,400 "deep sky" objects, with the publication of lists starting in 1786 (the first thousand) and 1789 (the second thousand). With additions from both his wife, Caroline, and son, John (1754 more objects), the General Catalogue of Nebulae and Clusters was eventually published in 1864.
Twenty-four years later, with additions by other 19th century astronomers and with editor John Dreyer, this became the New General Catalogue (abbreviated NGC) of 7,840 non-stellar objects. As photography was just starting to be used by astronomers around this time, the NGC was followed by two supplementary "index catalogues" (IC), also edited by Dreyer, in 1895 (1,520 objects) and 1908 (3,866 objects) mostly discovered on time exposure photographs. The 13,226 objects total continue to be referenced today mostly by their NGC and IC numbers, as they represent the brightest galaxies, star clusters, and emission nebulae in the night sky. Several hundred of the objects may be duplicates, mistakes, or non-existent, and coverage of the sky to comparable depths in the southern hemisphere was relatively poor until the latter parts of the twentieth century.
Nov 30, 1954 - Ann Elizabeth Hodges is hit by a 5 kg, grapefruit sized meteorite in Sylacauga, Alabama, after it comes through the roof of her house and ricochets around in the ground floor room where she was taking a nap on a sofa, bouncing off a radio before causing her a bruised hip. The meteorite was one of at least three fragments from the fall. A slice can be seen at the Smithsonian's National Museum of Natural History in Washington, D.C.

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