JUL - This Month's Astronomy History

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This Month in the History of Astronomy - July

Birthdays || Discoveries

Jul 1, 1916 - Iosif Samuilovich Shklovsky, Russian astrophysicist especially known for his wide ranging work in the pioneering field of radio astrophysics. Shklovsky was the first to work out that the radio wavelength radiation received from the Sun originated in the ionized gas of the corona (1946). He then went on to show that the radio wavelength radiation from the supernova remnant known as the Crab Nebula (M1) was synchrotron radiation, produced by high energy electrons circulating in strong magnetic fields. He also developed a way to separate radio energy detected from the Milky Way into thermal (produced by hot objects) and non-thermal components (like synchrotron radiation).
Shklovsky proposed that cosmic rays produced by supernovae explosions within about 300 light years of earth in the past might have been responsible for some of the mass extinction events found in the fossil record. And, in 1967, before pulsars were discovered, he studied the optical and x-ray radiation coming from Scorpius X-1 and determined that it could be explained by material accreting onto a neutron star.
Jul 2, 1906 - Hans Bethe, German-American astrophysicist who won the 1967 Nobel Prize in Physics for his work thirty years earlier on the theory of stellar nucleosynthesis and energy generation. During World War II, he was head of the Theoretical Division at the Los Alamos laboratory as part of the Manhattan Project to build the first atomic bomb.
Jul 13, 1924 - Donald Osterbrock, American astronomer best known for his many books and articles on the recent history of astronomy, which he took to writing fairly late in his career, as well as a graduate level textbook on ionization nebulae that went through multiple editions over more than a three decade span, the last revision being made just a year before he died in 2007.
Osterbrock started working as a graduate student around 1952, along with Stewart Sharpless (also a student), under W.W. Morgan at the University of Chicago and the Yerkes Observatoty on the elucidation of the Milky Way's spiral structure, by searching for O and B stars and their associated emission nebulae (all act as tracers), and determining their distances.
After several years as a post-doctoral fellow, instructor, and assistant professor at Cal Tech, Osterbrock moved to the University of Wisconsin-Madison, receiving tenure there in 1959. In 1973 he moved to UC-Santa Cruz and became director of the Lick Observatory for the next eight years, retiring in 1993. He was president of the American Astronomical Society (AAS) from 1988 to 1990, and received three major lifetime achievement awards: the Henry Norris Russell Lectureship from the AAS, the Gold Medal of the Royal Astronomical Society, and the Astronomical Society of the Pacific's Catherine Wolfe Bruce Gold Medal.
Jul 17, 1894 - Georges Édouard Lemaître, Belgian astrophysicist and cosmologist, who also, during WW I, witnessed the first use of poison gas (chlorine) in the history of warfare.
Lemaître was the first to theorize, using Einstein's general relativity theory, that a dynamical, expanding universe was possible, and that it would lead to the recession velocity of galaxies increasing with distance -- two years before Hubble's famous observational work on the subject appeared in print -- though the recession velocities of many galaxies was already known for several years by then, through the work (primarily) of Vesto Slipher at the Lowell Observatory. The paper, titled "An Homogeneous Universe of Constant Mass and Growing Radius Accounting for the Radial Velocity of Extragalactic Nebulae" (1927), included an estimate of what later would be called Hubble's constant, now the Hubble-Lemaître constant. Because it was published in a relatively obscure Belgian journal the paper was seen by few astronomers or cosmologists at the time, and an English translation did not appear until four years later. Lemaître first proposed what would later be called (derisively, by Fred Hoyle) the big bang theory, the "hypothesis of the primeval atom", as he called it in 1931 -- in which he also raised the possibility that the expansion of the universe was accelerating; this wasn't confirmed by observations until more than six decades later.
Jul 19, 1846 - Edward Pickering, pioneering American observer and Harvard College Observatory director from 1876 to 1919; this was the era of the introduction of photography in astronomy and the Harvard plate collection started during Pickering's tenure is still a valuable archival source of data.
Pickering was the first to adopt Norman Pogson's 1854 suggestion for a magnitude scale which is essentially the one still in use today (5 mags -> 100x), though he chose Polaris (at m=2.1) as the fundamental reference star, not realizing that it is slightly variable. The first great catalog of stellar magnitudes, containing 4,260 stars, was published in 1884. By 1908 the number was up to 45,000 stars, and it is estimated Pickering made 1.5 million visual photometric measures during its compilation.
Pickering was also responsible for the introduction of stellar color indices (c.1890), which compare brightnesses at blue and yellow wavelengths. After it was recognized that stars radiate thermally, like hot, dense solids, the color index became central to knowing what a star's photospheric ("surface") temperature was: bluer=hotter, redder=cooler.
Pickering made advances in spectroscopy such that it became possible to observe several stellar spectra simultaneously, leading in time to the Henry Draper Catalog (1918), with 225,320 stars, which is the basis for all modern stellar spectroscopic classification. HD numbers are still commonplace in observational astronomy for relatively bright stars -- brighter than about 9th magnitude -- since on average there are several (~5) per square degree of sky.
As if all that wasn't enough, Pickering also was instrumental in the construction of the first all-sky photographic atlas (1903), utilizing a southern observing station in Peru run by his brother. It consisted of 55 wide field plates and went down to the 12th magnitude.
Besides being awarded the Royal Astronomical Society's Gold Medal twice, Pickering became publicly well known in 1909 via an article in the magazine Popular Astronomy, when, in the wake of Percival Lowell's promotion of the idea that there was intelligent life on Mars, he suggested the practicality of signaling them with sunlight reflected off a mirror a half square mile in area.
Jul 22, 1784 - Friedrich Bessel, German astronomer and mathematician, who was the first ever, in 1837, to measure a star's parallax. (The star was 61 Cygni and the parallax was a mere 1/3rd of an arc-second). This ended a debate that dated back two millenia to the Greeks (Aristotle) about the distances to the stars. Bessel is also remembered for the mathematical functions that bear his name (1817), which appear in many areas of mathematical physics.
Bessel's early work on the orbit of Halley's Comet (1804) so impressed Heinrich Olbers that a position was found for him, and four years later the Prussian government put Bessel in charge of constructing the first large German observatory (1810-13), at Königsberg, where he was professor of astronomy and director until his death (1846). There he compiled accurate positions for 50,000 stars, and is also credited with the first two astrometric binaries: uncovering the invisible companions Sirius B and Procyon B by wiggles in the motions of the primary stars. Before he died, Olbers said his most important contribution to astronomy had been in recognizing and furthering Bessel's genius.
Jul 23, 1928 - Vera Rubin, American astronomer best known for her spectroscopy of disk galaxy rotation curves, suggesting the stars visible can only account for a small fraction of the mass needed to explain their velocities.
Her doctoral thesis advisor was the famed hot early universe theorist George Gamow, and one of her students was Sandra Faber, who headed up the Lick Observatory and helped design the Keck Observatory. Among many other honors, Rubin was only the second woman to be awarded the Gold Medal of the Royal Astronomical Society (1996), 168 years after Caroline Herschel received it (1828), and was awarded the Presidential Medal of Science in 1993.
"An Interesting Voyage", by Vera Rubin (2011).
Jul 25, 1573 - Christoph Scheiner, German astronomer who made early studies of sunspots, made improvements to the helioscope and telescope, and invented the pantograph (1603-05) -- a favorite device of Thomas Jefferson 150 years later, which copies documents, plans, or drawings to any scale.
Scheiner started observations of the Sun in 1611 with a well-mounted telescope he himself built, and was perhaps the first to understand the utility of projecting the image onto a white screen rather than viewing it directly through an eyepiece. He was the first to measure the Sun's period of rotation using sunspots, as well as noting the brighter patches known as faculae.
His early observations of sunspots were communicated to Galileo and Kepler using a pseudonym (because of his employment by the church), though he incorrectly thought they were small planets in close orbit about the Sun. Galileo somehow figured out Scheiner's identity and hinted he was guilty of plagiarism, even though confirmation of Galileo's discovery of sunspots was coming in from several other venues as well.
Scheiner observed both Mercury and Venus at inferior conjunction and concluded they orbited the Sun, but held to the geocentric view that the earth was stationary at the center of the universe.
Through years of observations he was able to be the first to measure the tilt of the Sun's sunspot rotation axis relative to the ecliptic, at 7½° -- only ¼° higher than the value in use today.
Jul 25, 1920 - Chushiro Hayashi, Japanese astrophysicist and cosmologist who made important early contributions to the theory of a hot Big Bang. He was also a pioneer in modeling star formation and stellar evolution, and is the namesake of the pre-main sequence stellar evolutionary 'Hayashi tracks' in the Hertzprung-Russell diagram.
In 1950, two years after Alpher, Bethe, and Gamow had first worked out the details of how nuclear synthesis in a very early, hot, dense universe would have built up heavier elements due to neutrons combining with protons, and in decreasing proportions as their mass increased (as is observed - gold is rare, carbon common), Hayashi showed that the weak (nuclear) interaction would have 'frozen' the ratio of neutrons to protons (at ~1:6) two or three seconds after t=0, making the resulting primordial helium abundance in the universe independent of density, and dependent almost entirely on the exact nature of the weak interaction.
In 1970 Hayashi won the Eddington Medal, awarded by the Royal Astronomical Society for investigations of outstanding merit in theoretical astrophysics, and in 2004 the Bruce Medal, awarded by the Astronomical Society of the Pacific for outstanding contributions to astronomy over a lifetime.
Jul 27, 1870 - B.B. Beltwood (Bertram Borden), American analytical chemist, radio-chemist, and geochemist who first measured the age of the earth using the radioactive decay of uranium into lead, upsetting ideas prevalent for decades that the earth was only about 100 million years old.
Beltwood came from a fairly prestigious New England family, his grandfather having been involved in the founding of Amherst College, and being Secretary there for decades afterwards. He also was a candidate for the governorship of Massachusetts. But Beltwood's father died when he was only two, so he was raised mainly by his mother and her family. He was a cousin to Ralph Waldo Emerson, and had an uncle who was a professor of mineralogy.
From the Curie's announcement of the discovery of radium in 1898, Boltwood started applying his laboratory talents and techniques to the investigation of radioactivity, and to uranium bearing minerals in particular. He worked or corresponded with many of the other pioneers in this field in the period before World War I, including Ernest Rutherford, with whom he engaged in a nearly constant exchange of letters during the first decade of the new century; Rutherford was in Cananda at McGill University then, so they met multiple times and became close friends. Beltwood was an independent, consulting chemist until he joined the faculty of Yale in 1906.
Lead had long been known to be present in uranium containing minerals. By 1905 the field was beginning to grasp that uranium was the "parent" of an entire series of radioactive decays that transformed it eventually into lead over long periods of time, and that in minerals -- rather than in pure, extracted compounds of uranium -- the ratios of the various elements would reach an equilibrium value that depended only on their relative lifetimes (half-lives). For U²³⁸ to Pb²⁰⁶ there were 8 alpha particles emitted (plus a few betas), though the concept of isotopes was yet a few years away, there was little realization of the many elements involved in the chain (beside radium, maybe polonium, and a few others given tentative names), and there was still uncertainty even that an alpha particle was the same as a helium nucleus with a mass of 4 atomic units.
It's also worth mentioning that Lord Kelvin's 1864 estimate of a 40-200 million year old earth, based on a simple cooling trajectory with no internal source of new heat, was already being called into question on account of the amount of energy obviously being given off by radioactive elements, which were found everywhere -- soil, water, air -- once people started looking.
It was Rutherford who first came up with the idea of using the Pb/U ratio as a dating method. It had previously been used the other way around, using standard geologic methods to try and infer which mineral from where was younger or older than another, and thus would be expected to have less or more lead in it. Boltwood always gave Rutherford full credit, but it was the former who did the careful lab work (1905-6) and established that a Connecticut uraninite sample was 410 million yearls old, while a specimen of thorianite from Ceylon measured 2.2 billion years old, using the best known values for the half-lives then available.
Age = Pb/U × 10¹⁰ years.
[Uranium's half-life was so long that its very low radioactivity made its half-life difficult to measure in purified samples; the radioactivity of minerals is 4-5x that of extracted samples because of the presence of what came to be known as "daughter" elements. Radium is perhaps the most famous of these Though present in only teeny tiny amounts, it's something like a million or more times "hotter" than uranium, because of its much shorter half-life (by that same large factor), and so it, along with some other intermediate isotopes, actually account for more of a mineral's radioactivity than the uranium present. It's also worth noting that except for refinements in the half-lives, the technique of geological dating of rocks using this method is still virtually the same as Boltwood used.]
The discovery made a huge splash with the public, as the age of the earth had been a highly contested subject at least since Darwin's famous work (1859). The Darwinians actually allowed for an infinite amount of time, since there was no quantitative value for the rate of evolution until after radioactive dating of geologic strata became available. The idea quickly caught on because it was simple enough that the public, by then fascinated with radioactivity, could easily grasp where the numbers came from. Lord Kelvin would die the next year (1907).
Largely forgotten now, Boltwood was the namesake for Boltwax, a wax with a low melting point useful for vacuum seals.
Jul 30, 1878 - Joel Stebbins, U.S. astronomer who first developed techniques for photoelectric photometry -- the measurement of the brightness of stars (and other objects) with electronic light meters.
Stebbins got his Ph.D. at the Lick Observatory (1901-03) and observed there at times until the age of 80, while being at the Washburn Observatory and University of Wisconsin from 1922-48; inbetween he was at the University of Illinois.
From 1909-25 he worked on the development of the photo cell, using it to measure light curves of eclipsing binary stars. By the 1930's he had moved into measuring the effect of interstellar absorption on starlight and the distribution of interstellar dust in the Milky Way. He also made early determinations of how this absorption depends on the wavelength of light.

Discoveries and other firsts

Jul 1, 1770 - Lexell's comet passes a mere 2.3 million km from Earth, less than 9 times the distance to the Moon.
Jul 1, 1917 - The 100" mirror arrived on Mt. Wilson. Businessman John D. Hooker donated the funds for the glass, which was the same as that used for the wine bottles made by the Saint Gobrain Glassworks in France. This was the last regular glass large telescope mirror made before Pyrex became the standard.
Jul 2, 1967 - The Vela gamma-ray satellite was launched with the intention of detecting nuclear bomb explosions but became famous for its serendipitous discovery of natural gamma-ray bursters. GRBs, the brightest electromagnetic events known to occur in the universe, were almost a complete mystery for decades, until it was possible to catch a few in other wavelength bands simultaneously. This placed GRBs in distant galaxies, where they could possibly be due to supernovae forming black holes or colliding/merging neutron star explosions, or stars being tidally torn apart by close passage by a black hole.
Jul 3, 2005 - The Deep Impact spacecraft crashes an 800 pound ballistic projectile into Comet Tempel 1 with the energy of about 5 tons of TNT -- to kick up ices and dust from its surface for its flyby mothership to analyze.
Jul 4, 1054 - The bright supernova recorded by Chinese astronomers and known today as Messier 1, the Crab Nebula, is thought to have first been visible on this day, likely in the morning around sunrise. It was visible during the daytime for about three weeks (23 days), and was likely also seen (and recorded) by Anasazi astronomers in the Four Corners area, based on rock art found in an alcove there which correctly depicts its relation to a crescent moon. The Chinese astronomers could see it in the night sky for more than 20 months, but it wasn't until the 20th century (roughly 1921 to 1942) that the Crab Nebula was positively identified by a number of astronomers who studied it as the 1054 A.D. supernova remnant.
Jul 5-6, 1687 - The publication date of Isaac Newton's Principia, with his three famed laws of motion. Edmond Halley was instrumental in getting the work to press, only 600 copies of the 500 page book were printed, and the estimate is that Newton's style of writing was such that there were only about 100 people in the world who were able to understand it.
Jul 6, 1924 - The Johnstown, Colorado, meteorite fall is observed by 200 mourners at a funeral in Weld County, who reported loud noises, as well as the smell of sulfur afterwards. The strewn field spread over about 10 miles, and 27 fragments were recovered. One nearly 50-pound chunk left a 6-foot deep crater in the ground. This is one of 90 meteorites ever found in Colorado, and probably the best observed fall.
The meteorite has been classified as a Diogenite, named for the ancient Greek philosopher Diogenes, who was the first to suggest that meteorites were not terrestrial rocks and originated from space. It is an achondrite (no chondrules) and believed to have come from the surface of the asteroid Vesta, though it is an igneous rock which cooled very slowly deep inside its parent body, resulting in large crystals. Radioisotope dating says it crystallized between 4.43 and 4.55 billion years ago.
Jul 9, 1979 - Voyager 2 made its closest approach to Jupiter. Over approximately the next decade it would fly by the other three gas giant planets in the outer solar system, being the first to both Uranus and Neptune.
Jul 11, 1991 - A total solar eclipse passes over Mauna Kea, Hawaii, and the largest telescope in the world (the Keck I 10-meter).
Jul 14, 1965 - First ever flyby of Mars: Mariner 4. The spacecraft sent back 22 pictures showing a heavily cratered, barren, almost lunar surface, finally putting to rest the notion of there being any advance lifeforms or civilization on the planet.
Jul 14, 2015 - The New Horizons spacecraft, almost a decade after its launch in 2006, became the first spacecraft to fly by Pluto. Two of its five moons (Kerberos and Styx) were only discovered after launch (in 2011 and 2012), and so were only barely able to be worked into the imaging plans, and two of the other three (Nix and Hydra) had only been discovered by the Hubble telescope about six months before launch.
Jul 16, 1850 - The first photograph of a star (Vega) other than the sun was made at the Harvard Observatory, by James Adams Whipple and William Bond, using the 15-inch refractor.
Jul 16, 1994 - The first of nearly two dozen fragments from Comet Shoemaker-Levy 9 impacts Jupiter, leaving the most visible features in the planet's atmosphere ever seen.
Jul 16, 2186 - Future history... the total solar eclipse with the longest duration between 2000 B.C. and 3000 A.D., 7 minutes and 29 seconds, will occur.
Jul 17, 334 - The Sicilian Firmicus is the first to report seeing solar prominences during an eclipse of the sun (annular in this case).
Jul 17, 1963 - The Nuclear Test Ban Treaty is signed, prohibiting the detonation of nuclear devices in the atmosphere. In order to monitor compliance with the treaty, the U.S. subsequently launches the first gamma ray detectors into orbit. In 1967 these inadvertently discover the first of many cosmic gamma ray sources, which are even today among astronomy's biggest mysteries.
Jul 17, 2017 - In what was called "the most challenging stellar occultation in the history of astronomy," NASA's New Horizons team, in a remote region of Argentina, observed in the direction of the distant Kuiper Belt object known as 2014 MU₆₉ using a "picket fence" of 24 mobile telescopes, of which five recorded the occultation. Only the Hubble Space Telescope can detect the 22-40 km diameter object directly (using reflected sunlight), which is over a billion miles farther from the sun than Pluto. The observations help refine the orbit of 2014 MU₆₉ for the Jan 1, 2019, flyby by the New Horizons spacecraft.
Jul 18, 1860 - First wet plate photo of an eclipse of the sun, the new process being 30x faster than a daguerreotype.
Jul 18, 1980 - India launches its first satellite.
Jul 18, 2011 - At least the fifth known witnessed fall of what turned out to be a Martian meteorite is accompanied by an early morning fireball and multiple loud booms around Tissint, Morocco. Several pieces were found three months later nearly 30 miles away. The first such fall (4 kg) occurred in Oct, 1815, near Chassigny, France. Another happened near Shergotty (Sherghati), India, fifty years later (5 kg - Aug, 1865). The 10 kg Nakhla, Egypt, fall was in 1911, and the largest, at 18 kg, occurred in 1962 near Zagami, Nigeria; this one dug a hole 2 feet deep hardly 10 feet from a likely very startled farmer.
Jul 19, 418 - The historian Philostorgius reports the first comet discovered during a total solar eclipse in Asia Minor.
Jul 19, 2009 - The Australian amateur astronomer Anthony Wesley observes a "bruise" in the atmosphere of Jupiter, an artifact from a collision with a small asteroid or piece of cometary material that hit on the side of the planet not visible from from earth, the site of which subsequently rotated into view.
Eleven months later he recorded a bright flash from an impact on the facing side of the planet. There was another ten weeks later, and a third visible flash was seen in Sep 2012. Four more have been recorded by observers since. The estimated size of these is less than 20 meters, though it probably takes one more than 10x larger to produce a darkening at the point of impact, something expected to occur about every seven years on average.
Jul 19, 2020 - The shortest sidereal day on record, by 1.4602 milliseconds, since atomic clocks started keeping track of the earth's spin rate. A total of 27 leap seconds have been added to Coordinated Universal Time (UTC) since the 1970’s to keep it synched up with the earth's rotation and generally lengthening days, the last of these being in 2016. Since the Earth is now spinning faster than at any time in the last 50 years there's talk of possibly having to add "negative leap seconds", and 2021 is expected to be the shortest year yet measured, to the tune of ~½ millisecond per day. The exact cause is not known but could be due to material of differeng densities in the core (or mantle) of the earth rearranging itself in terms of its distance from the center, changing the earth's moment of rotational inertia.
Jul 20, 1969 - The first humans set booted foot on the Moon: Apollo 11 lander with Neil Armstrong and Edwin Aldrin. Most people don't realize that Armstrong's famous words were meant to be "A small step for a man. A giant leap for mankind." The small stumble was the cause of the inordinately long pause between the two halves of the utterance, while Armstrong realized that on live TV there was only going to be the one 'take'.
Jul 20, 1976 - Viking 1 lands on Mars and the first images ever taken from that planet's surface are returned.
Jul 20, 2007 - An automated camera network operated since 2005 by astronomers at Curtain University in Perth, Australia, observe a fireball and recover multiple fragments within 100 meters of the calculated location on the ground, now known as the Bunburra Rockhole. The meteorite was a particularly rare variety and the tracking allowed its original location in the asteroid belt to be determined, as well as the fact that it nearly hit Venus in 2001.
Jul 22, 1962 - The first ever attempt at an interplanetary spaceflight, Mariner 1, launched to fly-by Venus, fails less than 5 minutes after launch and just seconds before the upper stage carrying the spacecraft was set to separate from its first stage booster rocket. About a month later (see Aug 27) Mariner 2 would successfully complete the mission.
Jul 23, 1999 - Launch of NASA's Advanced X-Ray Astrophysics Facility (AXAF), later renamed the Chandra X-Ray Observatory, after Nobel Prize-winning Indian-American astrophysicist Subrahmanyan Chandrasekhar.
At more than 25 tons, the telescope was the heaviest payload taken up by the Space Shuttle, largely on account of the two-stage rocket needed to put it into a high orbit, above earth's radiation belts; at apogee it is almost a third of the way to the moon. The system is 100x more sensitive than any previous x-ray telescope and has ½ arc-second resolution. It does not observe hard (high energy) x-rays, being confined to the 0.1 to 10 keV ("soft") part of the x-ray spectrum.
Jul 24, 1790 - The Barbotan meteorite fall in the south of France with a bright thunderous fireball that was seen by thousands of people occurs. Stones were collected across a wide area in several neighboring villages. Even though reports of meteorite falls had been recorded for centuries, meteorites were not then recognized as originating from solar system debris migrating from the asteroid belt into earth's vicinity. Partly due to the influence of such luminaries as Aristotle, Newton, Descartes, and Lavoisier, they were thought to somehow originate from earthly volcanoes, lightning, atmospheric dust, or rocks levitated by strong winds such as hurricanes; William Herschel had suggested they might be ejecta from lunar volcanoes, which he had recently claimed to observe. Or they were dismissed as being made up stories by peasants and simpletons, or attention seekers.
Jul 25, 2022 - An international team of researchers, part of the Cosmic Evolution Early Release Science (CEERS) Survey, studying the first deep field image data from the James Webb Space Telescope, of the massive lensing galaxy cluster SMACS 0723-7327 and the many objects beyond it which it magnifies and makes visible, report the highest known photometric redshift for a galaxy, at z ~16.7. This value is based on the relative brightness of a galaxy in broadband filtered direct images -- seven different bandpasses -- as well as a theoretical model spectral energy distribution (SED) curve for the light expected from just-forming galaxies, not on spectroscopic measures of known spectral lines, and is thus subject to revision as more observations are made. The seven bands, when de-redshifted, basically correspond to the optical/visual part of the spectrum, allowing comparison with local, present-day galaxies undergoing large rates of star formation. One other galaxy had nearly as high an imputed redshift, and the technique is thought to be able to find even more distant galaxies, up to about z=21.
Jul 26, 2006 - The first ever observed transit of a Uranian moon (Ariel) was made by the Hubble Space Telescope (photo at right), the first opportunity to do so since 1965 because of the extreme tilt of Uranus's spin axis and the moon's orbit being more or less in the plane of Uranus's equator.
Jul 28, 1917 - The announcement of the discovery of a nova in the galaxy NGC 6946 at magnitude 14.6 with the 60" telescope on Mount Wilson by George W. Ritchey.
As described by Sandage in the Hubble Atlas of Galaxies (1961), the nova itself was not important except for it causing Ritchey to get curious and start carefully inspecting the entire, nearly decade long, 60" plate collection for others like it, which netted two more novae that had been photographed in M31 in 1909.
At the Lick Observatory, Heber D. Curtis inspected the plate collection made with the 36" Crossley reflector and found novae in NGC's 4227 and 4321 -- two in the latter, both fainter than magnitude 15½. Within months others had chimed in and there were then eleven novae known in seven galaxies, with four in M31. Within two years, new observations had put the M31 total up to twenty-two.
One of these, known as S Andromedae (the second ever variable star, as nova were classified then, discovered in that constellation) had been observed in 1885 by Hartwig in M31 at a magnitude of 5.8 (though Sandage says 7.2). A decade later, Z Centauri had been discovered by Fleming at magnitude 8 near the center of NGC 5253. Earlier that same year, VW Virginus had been found by Wolf at magnitude 12½ in NGC 4424 in the Virgo Cluster of galaxies.
This confused state of affairs led Knut Lundmark in Sweden to sort things out in his 1920 Ph.D. thesis, discovering it made sense if there were two classes of novae: novae of the sort seen in the Milky Way -- twenty-six were known at that time -- and for which distances and thus absolute magnitudes could be determined to a greater or lesser degree; and the class of what are now called supernovae, 12 magnitudes (63,000x) brighter.
S And, and the "novae" seen in distant galaxies, were in this latter, new class, while the new ones being turned up in nearby M31 were of the former, old class. What was more, the apparent brightnesses observed only made sense if M31 was 650,000 light years away, and thus far outside the Milky Way. The supernovae seen in other galaxies were so faint these objects must be many times (30x) further still.
People were not immediately convinced by these incredible and revolutionary ideas from a new Ph.D., though the idea of the possibility of there being two classes of novae had first been floated by Heber D. Curtis (1917), but it would be four more years before Hubble, working with the new 100" telescope, turned up Cepheid variable stars in M31, M33, and NGC 6822 and finally settled the issue of whether or not the "spiral nebulae" were "island universes", as well as establishing the reality of the new class of exploding stars, though it would be several decades before it was understood what kind of explosions were taking place in both classes.
Jul 28, 1851 - The first photograph of the Sun during a total eclipse is made, a daguerreotype by Berkowski at Königsberg, Prussia.
Jul 29, 1878 - A total solar eclipse passes across parts of the United States. The eclipse was observed by the distinguished Simon Newcomb (see March 12), whose sketches of the event were widely reproduced in magazines of the day, and still seen today. The event caused such a stir that even Thomas Edison going to Denver to see it -- Colorado had only been a state for less than two years (so attack by "injuns" was still a widely hyped if somewhat mistaken fear just two years after Custer's Last Stand) -- was national front page news.
The eclipse was also the occasion for the first known astronomical observations from the summit of Pikes Peak, by the famed Samuel Pierpont Langely. The carriage road to the top of the peak was still a decade in the future, and the Army Signal Service's Weather Observatory there was less than five years old at the time.

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