JUN - This Month's Astronomy History

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This Month in the History of Astronomy - June

Birthdays || Discoveries

Jun 3, 1900 - Adelaide Ames, American astronomer and co-author of what would become known as the Shapley-Ames Catalogue of Galaxies.
After graduating from Vassar College in 1922, Ames went on to Radcliffe, becoming a research assistant under Harvard College Observatory director Harlow Shapley the next year, and then becoming the first woman to earn an M.A in astronomy in 1924.
Her work was primarily in the cataloging of galaxies in the constellations Coma and Virgo. Much of this work was done with a Zeiss Tessar lens, probably a "IIb" f/6.3 with F=360mm, as the scale was said to be 10 arc-minutes per millimeter (implying F=345mm), so the galaxies were so small and almost star-like that their brightnesses could easily be compared to stars on the same plate. The lens front element is listed as being only 61 mm in diameter -- less than 2½ inches.
In 1931, the finished catalog, A Survey of the External Galaxies Brighter Than the Thirteenth Magnitude was published, included nearly 2800 objects. This would become known as the Shapley-Ames Catalogue, and, later, after additions and extensions, as the Revised Shapley-Ames Catalogue of Bright Galaxies, which is still a valuable reference and in use nearly a century later. The intrinsically brightest galaxies, at the faintest level, are ~500 Mega-parsecs distant (~1½ billion light years.)
Ames would die shortly after the catalogue came out, when her canoe over-turned on a lake while vacationing in the Summer of 1932. There was always a bit of a mystery surrounding the accident, as she was reputed to be an excellent swimmer and her companion in the canoe made it safely to shore.
Jun 8, 1625 - Giovanni Cassini, the most notable early observer following Galileo. An Italian who headed the Paris Observatory for many years, Cassini was the first to observe seasonal changes on Mars and measure this planet's parallax (or distance), setting the scale of the solar system for the first time. He was the first to describe the bands and spots on Jupiter, and studied the Jovian moons' orbits. He discovered four moons of Saturn, but is best remembered for first seeing the division (now named after him) between Saturn's A and B rings.
Jun 9, 1812 - Johann Gottfried Galle, German observer who first saw Neptune. Galle is also noteworthy for having been Encke's assistant, and he's one of the few astronomers ever to have observed Halley's Comet twice -- dieing two months after the comet passed perihelion in 1910.
Jun 17, 1888 - Alexander Alexandrovich Friedmann, mathematician and cosmologist who published the first expanding, or non-static, models of the universe based on Einstein's general relativity. These originated in a singularity (size of the universe equals zero), so Friedmann was the first to hint at the Big Bang and use the phrase "the time since [the] beginning of the world" -- the age of the universe.
The paper went largely unnoticed for almost a decade, until Hubble had established his distance-velocity relationship (Hubble's Law), though Einstein did correspond with him, saying, "I am convinced Mr. Friedmann's results are both correct and clarifying. They show that in addition to the static solutions to the field equations [his and de Sitter's] there are time varying solutions with a spatially symmetric structure."
Friedmann also worked in meteorology, and in 1925 went on a balloon flight to study the upper atmosphere that set a Soviet altitude record (7.4 km, or more than 24,000 feet). He died two months later, probably of typhus of the stomach.
Jun 18, 1818 - Angelo Secchi, Italian astronomer who was one of the first to apply spectroscopy to the study of stars, conducting a sky survey of more than 4,000 of them and coming up with an early spectral classification system based on four groups, which he incorrectly attributed to differences in chemical composition (1867).
Secchi was also an early researcher into the use of photography in astronomy. By 1859 he had a complete set of telescopic photos covering the moon, and photographed the total eclipse of July 18, 1860.
Besides being an active observer of double stars, Secchi also proved that solar prominences were appendages on the Sun.
Secchi also worked out that the orbital period of a comet reaching halfway to the nearest star at its aphelion would be on the order of 100 million years, at that time the longest timescale astronomers had ever considered.
Jun 21, 1863 - Maximilian Franz Joseph Wolf, an astronomer based in Heidelberg, Germany, who discovered over 200 asteroids. At age 20, Wolf discovered a new comet with a period of 7.7 years. At a time when small bodies in the solar system were discovered visually, he invented the then new photographic technique whereby stars were recorded as pinpoints but rapidly moving objects like comets and asteroids would appear as short streaks during the time exposures. He also invented the "blink comparator" (or stereo-comparator), in which two plates taken some time apart could be alternately presented to the two eyes in rapid succession, so that objects which moved between the two exposures would appear to jump back and forth, and variable stars would grow and shrink in size, a very effective method for discovering such objects, especially in crowded star fields.
Wolf discovered the first Trojan asteroid (Achilles), confirming the advances in celestial mechanics and mathematics pioneered by Lagrange. He developed independently of Barnard the idea that the voids or dark regions in the Milky Way were not star gaps but regions of obstruction, now known to be due to instellar gas clouds containing dust, and discovered the North American Nebula in Cygnus. Wolf was also the first to pick up Halley's Comet when it came around in 1909. Over a thirty year period (1895-1926), Wolf turned up four of the first nineteen supernovae discovered in other galaxies. As if all that wasn't enough, Wolf discovered (1909) what's now called the Wolf-Lundmark-Melotte (WLM) dwarf irregular galaxy in western Cetus, the latter two independently coming across it eight years later; it's a distant and isolated member of the Local Group of galaxies.
Jun 21, 1915 - Wilhelm Gliese, German astronomer who specialized in the study and cataloging of nearby stars, found primarily from proper motion surveys. His catalog was first published in 1957, with a revised and updated version in 1969. Two supplements appeared in 1979 and 1991.
Jun 22, 1675 - Founding of the Royal Greenwich Observatory.
Jun 24, 1883 - Victor Hess, Austrian-born experimental physicist who discovered cosmic rays and shared in the 1936 Nobel Prize with Carl Anderson, who had discovered the positron (anti-electron) while studying cosmic rays. (Anderson discovered the meson that same year.) The term 'cosmic ray' had been coined by Robert Millikan in 1925.
Hess built on the work of Theodor Wulf, who had discovered (1910) that the degree of ionization in the atmosphere increases with altitude -- by taking an electroscope up the Eiffel Tower -- and concluded the source of the ionization was of an extra-terrestrial origin. Hess then made a dozen balloon ascents (1911-12), reaching a height of 16,000 feet, where the ionization is 4x what it is at ground level, even making an ascent at "night", during the Apr 17, 1912, solar eclipse; from this he showed the sun was not the source of the ionization.
By 1931, after two years in the U.S. working on issues related to radioactivity with both a radium producer and the Dept. of the Interior's Bureau of Mines, Hess became professor of physics at Innsbruck University, director of its Institude of Radiology, and established a cosmic ray observatory on nearby Hafelekar Mountain. Hess was forced to flee to the U.S. by the Nazi occupation of Austria in 1938 because his wife was Jewish, and he spent the rest of his life based in New York, including nearly twenty years as professor of physics at Fordham University, after becoming a U.S. citizen during World War II.
Jun 24, 1915 - Fred Hoyle, British astrophysicist who was instrumental in the development of the theory of stellar nucleosynthesis, and who coined the term "big bang" to describe a cosmology he disliked, being an inventor of, and a chief proponent for, the rival steady state theory.
In what can only be described as an act of inspired brilliance, Hoyle, realizing that something special was needed to make it possible for evolved stars to synthesize carbon from helium, predicted the existence of a nuclear resonance energy level that was subsequently found right at the energy he'd calculated, making the otherwise impossible triple-alpha process "go".
Hoyle held the Plumian chair at Cambridge, as had people like George Darwin and Arthur Eddington.
Jun 25, 1894 - Hermann Oberth.
Jun 26, 1730 - Charles Messier, famed French comet hunter, who cataloged the 100 or so bright nebulae and star clusters known nowadays by their M numbers because he kept confusing these stationary objects with possible new comets, which is what he was really after.
Jun 26, 1914 - Lyman Spitzer, U.S. theoretical astrophysicist who concentrated on the interstellar medium and star formation. Spitzer got his education and was at Yale from 1931-47, except for a year at Cambridge as a student of Arthur Eddington, before moving to head Princeton's astronomy and astrophysics department.
Namesake of the Spitzer infrared space telescope (2003), in honor of his early advocacy for space telescopes in general and being a steadfast proponent for fifteen years -- 1963 until its funding in 1978 -- for what became the Hubble Space Telescope.
Jun 27, 1767 - Alexis Bouvard, French astronomer and mathematician. Director of the Paris Observatory, after having been a student there under Pierre-Simon Laplace.
Bouvard discovered eight comets and determined their orbits. His careful observations of the irregularities in the motion of Uranus, and his hypothesis of the existence of an eighth planet in the solar system, led to the calculations by John Couch Adams and Urbain Le Verrier which resulted in Neptune's discovery a few years after his death in 1843.
Jun 29, 1868 - George Ellery Hale, solar astronomer, discoverer that sunspots had magnetic fields, and inventor -- at the age of 21 -- of the spectroheliograph. He was the founder of the Astrophysical Journal.
Hale is the namesake of the 5-meter (200") telescope on Mt. Palomar, and helped found the Yerkes, Mt. Wilson, and Palomar Observatories. The 5-m was dedicated on June 3, 1948 and continues to be the largest telescope in the continental 48 states.

Discoveries and other firsts

Jun 5, 2012 - The date of the last transit of Venus, among the rarest of predictable astronomical phenomena. In the photo at right, north is roughly up and the direction of Venus's motion was from about 11 o'clock towards 3 o'clock; the entire transit took about 6½ hours. The next transit visible from earth won't happen until December 2117.
June 8, 1918 - Nova Aquilae 1918, first seen by Polish medical professor and amateur astronomer Zygmunt Laskowski, is confirmed by UK amateur Grace Cook. Peaking at a visual magnitude of -½, it was the brightest new star to appear in the sky since Kepler's supernova (1604) and was brighter than every other star in the sky except Sirius and Canopus.
At a distance of 310 parsecs, in 1964 Robert Kraft determined the now faded star of about the 11th magnitude was an eclipsing binary, and thus originated the modern theory that all common novae (or "cataclysmic variables" as they're often called) occur in a mass transfer, close binary system containing a white dwarf. Nova Aquilae 1918 has a period of only 3 1/3 hours.
June 9, 1803 - William Herschel presents a paper to the Royal Society establishing that close double stars are physically bound binaries in orbit around each other and not just chance alignments.
Herschel had started out two dozen years earlier with an entirely different goal in mind: trying to measure a star's parallax. The idea was that if all stars are instrinsically about the same brightness then the fainter star in a close pair could be taken to be a fixed reference point at infinity, and the parallax of the brighter, closer star could be measured relative to it. After two decades it became clear the motion for some of his sample was orbital not parallactic.
June 9, 1982 - Dr. Edward F. Guinan of Villanova University announces the discovery of two rings around Neptune at the annual summer meeting of the American Astronomical Society, after re-examining photographic data gathered at a New Zealand observatory in 1968 with Craig C. Harris and Frank P. Maloney.
Subsequent observations when Neptune occulted a star suggested the rings might not be complete, but consist of segments or arcs. The Voyager 2 spacecraft resolved the issue in its Aug 25, 1989, flyby, showing three main rings, plus two more bordering the middle one; the outermost, named the Adams Ring, consisted of five pieces, explaining the earlier inconsistent occultation observations.
[Photo at right shows Neptune in the IR from the James Webb Space Telescope, with two of the rings clearly visible; the moon Triton is above and to the left. Neptune is dark because its methane atmosphere absorbs strongly at the IR wavelength used.]
June 9, 1988 - Pluto occults a 12th magnitude star and the light curve measured by eight groups definitively showed Pluto to have an atmosphere.
Updated, last-minuted astrometry allowed the Kuiper Airborne Observatory, led by J. Elliot, to track the centerline of Pluto's shadow across the South Pacific Ocean for 2½ minutes. The high time resolution thus achieved led to the discussion of possible dusty haze or photochemical aerosol layers and thermal gradients.
The atmosphere has an extent almost comparable to Pluto's radius (1150 km), with a scale height of ~60 km, and a half-light temperature and pressure of 67°K and 0.78 microbars, for an assumed pure CH₄ (methane) atmosphere. Methane had previously been observed in the spectrum of Pluto, but it wasn't clear if it was a solid on the surface or in the gaseous form above it (or some combination); the occultation showed that most of the spectral signature is due to a frozen methane surface. The half-light level corresponds to ~125 km above the surface, or about an eighth of the atmosphere's measurable extent.
June 11, 2008 - Launch of the Fermi gamma-ray observatory.
Jun 12, 1894 - Oliver Lodge, Professor of Physics and Mathematics at the University of Liverpool, makes the first known attempt to detect extraterrestrial radio waves, from the sun, but gets an inconclusive (null) result. The theory of the sun's corona had first been worked out the previous year by German physicist Hermann Ebert, though there was uncertainty then as to whether any radio wavelength radiation would penetrate the earth's atmosphere. By then it was known from laboratory experiments that radio waves could be absorbed by rarefied gases, so there was speculation that the upper atmosphere (of either the earth or sun) might be radio opaque. There were several other unsuccessful attempts over the following decade to detect the sun at radio wavelengths, but then the matter was dropped and it was not until World War II and the development of radar receivers that this was done.
When Heinrich Hertz died prematurely of cancer in 1894, Lodge, who was working on similar 'Hertzian wave' detection equipment, gave an honorary lecture and demonstration at the Royal Institution of London, where he stated his hope "to try for long-wave radiation from the Sun" shortly. It would be several decades before Karl Jansky and Grote Weber again took up the task of detecting extraterrestrial radio waves, though during the close Mars opposition of 1924 the U.S. Army Signal Corps did try to tune in on any Martian broadcasts, following unsubstantiated reports from both Nikola Tesla and Guglielmo Marconi about having received signals possibly from Mars. Jansky detected the Milky Way at radio wavelengths more than a decade before radar operators during WWII picked up static which was logically due to the sun, since enemy planes would often attack with the sun at their backs in order to be difficult to see.
Jun 13, 1983 - Pioneer 10 becomes the first manmade object to leave the solar system, in the direction of the constellation Taurus.
Jun 16, 1794 - A widely seen meteorite fall occurs near Siena, Italy, at around 7 PM, showering the outskirts of town with stones. A local professor, Ambrogio Soldani writes up a 300 page book documenting the hundreds of eyewitness accounts.
Jun 16, 1806 - The Spaniard José Joaquin de Ferrer, observing an eclipse in Kinderhook, NY, first uses the term "corona" to describe the outer atmosphere of the sun visible during a total eclipse.
Jun 16, 1963 - Valentina Tereshkova became the first woman ever to go into space, aboard the USSR's Vostok 6. Her solo flight is still unique. Twenty years later, on the 18th, Sally Ride became the first American woman in orbit, aboard the Space Shuttle.
Jun 22, 1968 - Joseph Weber announces the detection of a gravity wave using his aluminum cylinder detector (photo at right), but the result could not be confirmed.
Weber's detector was a 1-meter aluminum cylinder rigged with numerous piezo-electric contact microphones, acting like a small seismometer network, to sense any acoustic vibrations (quakes) created in the cylinder by the passage of a spacetime distorting gravitational wave in the aluminum.
Jun 22, 1978 - James Christy of the US Naval Observatory in Flagstaff, AZ, discovered Pluto's satellite Charon, about which very little was known until the flyby of 2015 by the New Horizons spacecraft. Pluto itself was discovered in Flagstaff (at the Lowell Observatory, only 4 miles away) in 1930.
Jun 22, 2019 - An incoming asteroid that hit the earth, with a diameter of only 4 meters, is spotted and tracked in realtime for the first time by the Asteroid Terrestrial-impact Last Alert System (ATLAS) and the second Pan-STARRS telescope. Twelve hours later the Nexrad weather radar in San Juan, Puerto Rico, recorded the asteroid burning up in the atmosphere over the ocean.
Jun 22-26, 1975 - Seismometers left on the moon by Apollo astronauts record more large meteoroid strikes in a five-day period than were detected over an entire five-year period of operation. The estimated size of the impacting boulders was about one ton, and would have created a spectacular fireball shower on earth, except that it occurred on earth's dayside and went otherwise undetected. It is thought the event was associated with the Beta Taurid meteor shower.
[Graph at right shows average daily number of meteoroids hitting the moon from 1972-76.]
Jun 24, 1881 - Sir William Huggins, one of the most prominent British astronomers of the late Victorian era, makes the first photographic spectrum of a comet (1881 III) and discovers cyanogen (CN) emission at violet wavelengths, a common feature in cometary spectra, which caused near mass hysteria 29 years later as the Earth passed thru the tail of Halley's Comet and people thought the whole planet would be poisoned.
Using only an 8" telescope, Huggins was the first to show that some nebulae -- a planetary nebula in Draco, NGC 6543 (known informally as "The Countdown Nebula"), as well as the Orion nebula -- had an emission line (non-stellar) spectrum, and were thus not star clusters but were instead composed of rarified hot gas. A nova he observed showed both a star-like (continuous) spectrum and carbon emission lines, suggesting a star surrounded by a cloud of hot gas from the explosion. Huggins was the first to record any astronomical spectrum photographically, and is credited with measuring the first ever stellar radial velocity (of Sirius).
Jun 25, 1178 - The medieval monk known as Gervase of Canterbury, along with several others, looking at a young waxing crescent moon, see the upper "horn" split in two, a "flaming torch sprang up", "spewing out fire, hot coals, and sparks", and after some time "the moon from horn to horn ... took on a blackish appearance". It is thought they saw the impact which formed the 22 km impact crater Giordano Bruno just around the limb of the moon on its far side, which shows many bright rays like other young craters.
Jun 26/7, 1949 - The asteroid Icarus is discovered by Walter Baade on plates taken with the then-new 48" Palomar Schmidt camera/telescope. Noticing the relatively large length of the track during the time exposure, Baade knew the object was moving unusually fast; he took more exposures of it on two subsequent nights. Though he'd serendipitously discovered the asteroid Hidalgo almost 30 years earlier (the first of a class known as "Centaurs"), Baade was doing star cluster, variable star, and galaxy research, so he turned the plates over to Seth B. Nicholson, the solar system expert at Mount Wilson and Palomar, who then did the position measurements and reductions, and calculated its orbit. It was just four million miles from Earth at the time of discovery.
Following criticism from the International Astronomical Union on the naming of an asteroid for his wife, Baade had done a calculation in the late 1930s showing there were somewhere around 100,000 asteroids brighter than the 19th magnitude, which could be discovered by the then-existing telescope technology, and this far exceeded the number of names available from Greek mythology. So other names were going to have to be used sooner or later.
Icarus is notable for having a perihelion distance inside the orbit of Mercury, only 0.19 A.U.. The high eccentricity of its orbit (e=0.83) takes it out to beyond the orbit of Mars, so it crosses the orbits of all four terrestrial planets. Until 1983, when Phaethon was discovered, Icarus came closer to the sun than any other known asteroid -- and closer than most comets. Now, nearly 400 asteroids are known which cross Mercury's orbit.
Icarus makes periodic close approaches to earth (always in June, at intervals of 9, 19, or 28 years), so it was the first asteroid to be observed by radar. It's less than a mile in diameter and spins once every 136 minutes, so it's near the point where it would fly apart were it a "rubble pile" asteroid; it's thought to be a solid, stony, S-type asteroid. Variations in its orbital parameters have been used to determine Mercury's mass and test Einstein's theory of general relativity. Its next close approach to earth takes place Jun 13, 2043, at about 23 times the distance to the moon.
Jun 27, 2018 - Japan's Hayabusa 2 spacecraft reaches the asteroid Ryugu. After detailed mapping of the object, from a distance of, first, 20 km, and then 5 km, for a couple of months, it will swoop in to scoop up samples of the surface debris and return these to earth in Dec 2020.
Jun 29, 1961 - The first nuclear powered satellite (the US's Transit 4A) was launched.
Jun 30, 1908 - Date of the great Tunguska impact in Siberia. And, as of 2014, Asteroid Day, created to increase public awareness of the threat of meteor strikes, even though many have speculated the event was caused by a comet since it left no crater.
Jun 30, 1973 - John Beckman and other scientists use the Concorde supersonic jet flying at 1250 mph to lengthen the duration of a solar eclipse's totality to 74 minutes, about 10x longer than can ever be observed from a stationary location on the earth's surface. The moon's shadow typically moves at even greater velocities, like at least 1500 to 1700 mph, so even the Concorde wasn't able to fully keep up with it.
June, 1893 (two weeks near the end of the month) - George Ellery Hale, namesake of the Mount Palomar 200" telescope, heads up a team that makes only the second known astronomical observations from the summit of Pikes Peak.
Hale tried unsuccessfully many times over many years to detect the Sun's corona during the daytime and without a total eclipse, and ended up in Colorado after finding apocryphal the folk tales that at the bottom of the Grand Canyon the daytime sky overhead was "nearly black".
Hale's wife, Evalina, suffered from altitude sickness and headaches the whole time, and Hale tended to her, while famed pioneering astrophysicist James E. Keeler (who had observed from Mount Whitney a dozen years earlier with the also famous Samuel Pierpont Langley) made the actual observations -- which were scotched "by clouds, smoke from forest fires, and even swarms of insects flying above the mountain, all scattering sunlight into the telescope." The small expedition west was back in Chicago by the Fourth of July.

©2002-2023, Chris Wetherill. All rights reserved. Display here does NOT constitute or imply permission to copy, republish, or redistribute my work in any manner for any purpose without prior written permission.

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