JAN - This Month's Astronomy History

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This Month in the History of Astronomy - January

Birthdays || Discoveries

Jan 2, 1920 - George Herbig, American astronomer who spent his career at the University of Hawaii Institute for Astronomy and is best known for his work on stars in the early stages of evolution and on the properties of interstellar dust. He got his Ph.D. at the University of California/Berkeley in 1948 for "A Study of Variable Stars in Nebulosity".
Intermediate mass pre–main sequence stars are named Herbig Ae/Be stars due to his work -- the little "e" stands for emission, as in emission lines in their spectra -- and Herbig–Haro objects are bright patches of nebulosity near stars excited by a bipolar outflow from the star being born.
Herbig was awarded the Henry Norris Russell prize of the American Astronomical Society in 1975 and the Bruce Medal of the Astronomical Society of the Pacific five years later, both for lifetime contributions to the field of astronomy.
Jan 8, 1942 - Stephen Hawking, British theoretical astrophysicist who specialized in black holes. Exactly the opposite of his predecessor at Cambridge, Fred Hoyle (see June 24th), Hawking was thoroughly orthodox in his cosmology.
Jan 10, 1936 - Robert W. Wilson, co-discoverer with Arno Penzias of the cosmic microwave (3°K) background; 1978 Physics Nobel Laureate.
Jan 12, 1830 - The founding of what in 1831 would become the Royal Astronomical Society, by John Herschel, Charles Babbage, James South, and several others. The first "AS", the RAS has published it's Monthly Notices continuously since 1831.
Jan 14, 1881 - Francis Pease, American astronomer who specialized in optics and instrumentation, especially large telescopes and optical interferometers.
Pease started at the Yerkes Observatory as an assistant to George Ritchey, who built many of the large telescopes of the time. Pease became an astronomer and instrument maker at Mount Wilson about the time the 60" telescope went into operation, where he helped design the engineering on the 100" telescope. As an assistant to ALbert Michelson, he collaborated on a stellar interferometer fitted to the 100" which made the first direct angular diameter measurement of a star (Betelgeuse). He later designed and built a 50-foot interferometer and was involved in the design of the 300" telescope, which became the 200".
Jan 19, 1747 - Johann Bode, publicizer of the Titus-Bode law, a nearly geometric progression of the distances of the planets from the Sun.
Jan 19, 1851 - Jacobus Kapteyn, Dutch astronomer who compiled data on the positions and brightnesses of 455,000 stars, primarily in the Southern hemisphere, and transformed them into distributions and motions to create the first modern model of the size, structure, and dynamics of the Milky Way Galaxy.
Jan 20, 1573 - Simon Mayr, who observed the moons of Jupiter at nearly the same time as Galileo and gave them the Greek names in use today (see below).
Jan 21, 1792 - John Couch Adams, who predicted the existence of Neptune.
Jan 21, 1908 - Bengt Strömgren, developer of the theory of ionization nebulae (H II regions) such as the Orion and Trifid (M20) nebulas, in which hard ultraviolet radiation from very hot, O-type stars, photons with ≥13.6 eV energy, ionizes the surrounding hydrogen gas, heating it up to temperatures of several thousand degrees Kelvin (up to ~10,000°K).
When the free electrons recombine with the hydrogen ions (bare protons), they emit light of specific energies (wavelengths) as they cascade down through the hydrogen atom's energy levels to the ground state in a number of different ways, yielding the observed spectrum rich in hydrogen emission lines. [See energy level diagram at right.] The gas essentially fluoresces by absorbing light of one wavelength and converting it to light of other, visible wavelengths.
The finite number of UV photons emitted by the stars means the "Strömgren sphere" will be of finite radius, so if the gas cloud in which it occurs is of fairly uniform density, the H II region will look approximately spherical and Strömgren's equations give its diameter -- or the gas density if the size can be determined some other way. This is one of the few ways to get gas densities in star forming regions, since O stars have such short lifetimes that they're always found where this is an active process.
Strömgren also developed a system of medium bandwidth photoelectric photometry which allowed stellar spectral classification without requiring an actual spectrum.
The Copenhagen Observatory was Strömgren's home from the time he was born until 1931, as his father was appointed professor of astronomy at Copenhagen University (1907) and was the observatory's director until his retirement in 1940.
He gained much during his student years from the close proximity with the Neils Bohr Institute, working out the poorly known composition of stars as being ~70% hydrogen and ~26% helium (by mass) in his 30's.
After World War II Strömgren moved to the US and became director of the Yerkes and McDonald Observatories, staying there for six years. In 1957 he was appointed the first professor of theoretical astrophysics at the Institute for Advanced Study in Princeton, where he got Albert Einstein's office in Fuld Hall after the latter's death two years earlier.
He received both the Gold Medal of the Royal Astronomical Society (1962) and the Henry Norris Russell Lectureship from the American Astronomical Society (1965).
Jan 24, 1882 - American solar astronomer Harold Babcock, who proposed that the sunspot cycle was a result of the Sun's differential rotation and magnetic field (1961).
Jan 25, 1736 - Joseph Louis Lagrange, famed French mathematician who made important contributions to the field of celestial mechanics.
Jan 28, 1611 - Johannes Hevelius, who published the Selenographia, the first detailed maps of the Moon (1647).

Discoveries and other firsts

Jan 1, 1801 - Italian Giuseppe Piazzi discovers Ceres, the first known asteroid, in the constellation Taurus. Later more properly referred to as a minor planet or planetoid, Piazzi observed the object until severe illness stopped him February 11th and he only notified others of his discovery by letters sent January 24th. By the time others got on it, Ceres was too close to the Sun for observation and was not relocated when it emerged in September. Gauss's refined method for calculating orbits allowed Ceres to finally be recovered in Virgo on the last day of 1801 and the first of 1802.
Jan 1, 1889 - The date of a notable US total solar eclipse. Though more than half the eclipse occurred over the Pacific Ocean, the centerline came onshore in extreme northern California, arced upward through south Idaho, went just northwest of Yellowstone Nat'l Park, and then continued up through southern and north-eastern Montana, and extreme north-western South Dakota, before heading up into Manitoba, Canada.
Both Edward Pickering (Harvard College Observatory) and E.E. Barnard (Lick Observatory) organized elaborate teams of scientists to study multiple aspects of the eclipse. This was also the eclipse that Lame Deer in his biography says happened "between 1880 and 1890" which led to the development of the Ghost Dance (Nanissáanah), a religious movement incorporated into numerous Native American belief systems in the Great Plains and the West at the end of the nineteenth century.
Jan 1, 1925 - The announcement, at a meeting of the AAS, of Hubble's conclusive results for Cepheid variable distances in spiral nebulae, which established the extragalactic nature of such "island universes". Hubble was not present at the meeting and his paper was read by (the great) Henry Norris Russell (Oct 25, 1877), though the results had circulated within the field for almost a year by then. Some fifteen months earlier Hubble had first found Cepheids in the Andromeda Galaxy and determined its distance as 300kpc, based on the calibration then in use, the modern distance being 778 ±33 kpc.
Jan 1, 2019 - NASA's New Horizons spacecraft, 3½ years after flying by Pluto, flies by the first Kuiper Belt object ever, KBO 2014 MU69, temporarily named "Ultima Thule", which wasn't even discovered until eight years after the launch of the spacecraft in 2006, showing it to be what appears to be two snowballs stuck together by a presumed collision long ago. Ten months later the object was given the permanent name Arrokoth, the Powhatan word for ‘sky’, a Native American tribe indigenous to Maryland, where mission control for New Horizons is located.
A photo taken looking back towards the object and the sun on the outbound part of the flyby suggests it is flatter than first appearances give; it may be more like "a meatball stuck to a puffed up pancake". Analysis of the composition of the surface (photo at right) shows both halves were assembled from a collection of debris with differing compositions. Calculations show the two parts then collided at a velocity of ~2 meters/sec, a brisk walking pace.
Jan 2, 1825 - The discovery of the Quadrantid meteor shower, by Italian astronomer Antonio Brucalassi: "the atmosphere was traversed by a multitude of the luminous bodies known by the name of falling stars." It was observed in a couple of subsequent years by others before being mentioned as a possible annual shower. It is named for its radiant being in a now obsolete constellation called Quadrans Muralis (the Mural Quadrant) located on some 19th-century star atlases, near the point of meeting between Hercules, Boötes and Draco. In 1963, researchers speculated that the stream's parent comet was captured by Jupiter about 4000 years ago. In 1979, it was predicted that the Quadrantids would no longer be visible by the year 2400, due to perturbations of its orbit by Jupiter.
Jan 2, 1959 - The USSR's Luna 1, the first Moon probe, is launched and becomes the first extraterrestrial spacecraft.
Jan 3, 1888 - The James Lick 36" refracting telescope sees first light; it would be the largest refracting telescope in the world until the Yerkes 40" went into operation in 1897.
Construction of the Lick Observatory started in 1876 with a $700,000 bequest from Mr. Lick. The observatory first started supplying Railroad Standard Time signals to the Southern Pacific Railroad over telegraph lines in 1886.
Jan 4, 2019 - China's Chang'e-4 spacecraft (with rover) makes the first ever landing on the far side of the moon.
Jan 4, 2020 - The asteroid 2020 AV₂ is first discovered at about magnitude 18 with the 48-inch Schmidt telescope at Palomar Observatory. With more observations over subsequent days and then during the asteroid's recovery in 2021 (July 18-19), orbital calculations show it stays entirely within Venus's orbit, a first for any known asteroid.
The asteroid has a typically slightly reddish color and an estimated diameter of 1-3 km. Its orbit is close to being in a 3:2 resonance with Venus, but is believed to be unstable over periods that are short compared to the age of the solar system (meaning ten to forty million years), so it probably hasn't been where it is for very long, and it will likely smash into Venus over a similar time scale.
Jan 4 thru 15, 1610 - Arguably the most important days in the history of astronomy, Galileo Galilei points his newly developed telescope at the sky and observes craters and mountains on the Moon, moving spots on the Sun, four moons revolving around Jupiter, the phases of Venus, and the almost innumerable stars of the Milky Way.
[Jan 7 was the night he discovered three of Jupiter's four largest satellites (now called the Galilean Moons), electrifying Europe with the proof that not all bodies revolve around the Earth. (Ganymede was discovered 6 days later.)]
Jan 6, 1949 - The first atomic clock was built. Based on earlier theoretical work by Isidor Rabi (with then student Norman Ramsey), this clock used ammonia as its pendulum. It wasn't until 1957 that the first cesium beam device was built. The best primary cesium standards now keep time to about one-millionth of a second per year, making possible high resolution radio interferometry, tests of Einstein's theory of general relativity, the Global Positioning Satellite system, and accurate determinations of the Earth's changing rotation rate.
Jan 8, 2014 - A fireball that passed over Papua New Guinea and exploded near Manus Island entered earth's atmosphere with the incredible velocity of 130,000 mph, which, along with its trajectory, makes it 99% certain it had an origin outside our solar system, in interstellar space.
Some of the data needed to verify the researcher's (Amir Siraj and Avi Loeb, Harvard) calculations was considered classified by the U.S. government, but was eventually made available by the U.S. Space Command. (Some of the sensors that detect fireballs are operated by the U.S. Department of Defense, which uses the same technologies to monitor the skies for nuclear detonations.)
This makes the estimated ½-meter sized meteorite, known as CNEOS14, retroactively the first interstellar object ever detected in our solar system. It's possible pieces of the meteorite are now sitting on the floor of the South Pacific Ocean. Further analysis of its trajectory published in Nov 2022 is consistent with it perhaps having been deflected in our direction by an unknown massive object in the far outer solar system, referred to as Planet 9, between 30 and 60 years ago.
Jan 9, 1839 - South African Thomas Henderson, using geometrical parallax, first measures the distance to a star (Alpha Centauri) other than the Sun.
Jan 10, 1946 - The US Army's Signal Corps successfully bounces the first radar waves off the Moon. This was done by John DeWitt and Project Diana (the roman goddess of the moon), at the Evans Signal Laboratory overlooking Shark River Bay in northern New Jersey.
Modified SCR-271 army surplus radar equipment was used, and the project was kept "under the radar" (so to speak) by ostensibly being about radar detection, and possible disabling, of guided missiles like the V-2, since astronomy was not really part of the Army's mission.
The frequency used was 111.5 MHz, and a 50Hz bandwidth was employed. The team did not accurately measure the time delay for the beam to get to the moon and bounce back (giving its distance), but the narrow bandwidth did allow them to measure accurate frequency shifts due to the Doppler effect, and thus the relative motions between the moon and the radar location (mostly due to the earth's rotation).
Jan 11, 1787 - Willian Herschel discovers Oberon and Titania, Uranus's largest satellites.
Jan 14, 1990 - NASA's Cosmic Background Explorer (COBE) satellite releases its all-sky temperature map of the microwave background radiation thought to be left over from the era some 380,000 years after the Big Bang, when the universe went from being an opaque plasma at about 3000-3500°K to a transparent gas, releasing the light trapped in it. Since the universe has expanded in size by about 1000x since, this radiation is now seen with a temperature of about 3°K. The splotches are minute temperature variations that are thought to represent small density variations which would be responsible for the subsequent growth of structure in the universe, such as super-clusters of galaxies and the large voids between them.
Jan 15, 1969 - The pulsar at the center of the Crab Nebula (M1) supernova remnant is first observed in the visual (or "optical") part of the spectrum by a team of University of Arizona astronomers (Cooke, Disney, & Taylor) using the Steward Observatory 36-inch reflector on Kitt Peak, which had previously been sited on campus in Tucson until the light pollution got too bad in the 1960's.
The pulsar's exact position had only been nailed down two months earlier with the Arecibo radio telescope (see Nov 15), and the detection of the flashes in the visible part of the spectrum was duplicated within a few days at at least three other observatories.
This observation is difficult because the pulsar rotates about thirty times per second, and flashes twice per rotation. So to resolve the cycle requires about ten exposures every 1/30th of a second, or an exposure time of shorter than 1/300th second. Such short exposures are not going to allow one to detect very faint stars. So, how was it done? It required the invention of image intensifier tubes (aka "night vision" equipment) and high speed video cameras, the latter being one of those Apollo program spin-offs often talked about.
The photo at right shows one half of a cycle from the discovery sequence of frames.
Jan 15, 2006 - The Sample Return Capsule from NASA's Stardust mission separates from the main spacecraft and is on the ground a little more than four hours later. It was the fastest reentry speed into Earth's atmosphere ever achieved by a human-made object, going from Mach 36 to subsonic speed in under two minutes, experiencing 34g's of deceleration.
The capsule brought back more than a million particles of cometary interstellar dust, totalling all of 1 milligram of material, though only several dozen of the particles are thought to be of interstellar origin. The dust grains are being studied and analyzed by a volunteer team through the citizen science project, Stardust@Home.
Jan 17, 1921 - Vesto Slipher at the Lowell Observatory in Flagstaff, AZ, announces the then incredible radial velocity of 1,770 km/sec for the 11th magnitude galaxy NGC 584 in Cetus. The story of the "Celestial Speed Champion" was picked up by the New York Times and ran two days later on page 6:
"Like most spiral nebulae, this one is extremely faint, and to observe its velocity requires an exceedingly long photographic exposure with the most powerful instrumental equipment. This photograph was exposed from the end of December to the middle of January in order to give the weak light of the nebula's spectrum time to impress itself upon the plate.
"...If the above swiftly moving nebula be assumed to have left the region of the sun at the beginning of the earth, it is easily computed, assuming the geologists' recent estimate of the earth's age, that the nebula now must be many millions of light years distant.
"The velocity of this nebula thus suggests a further increase to the estimated size of the spiral nebulae themselves as well as to their distances, and also further swells the dimensions of the known universe."
Note the implicit acceptance here of the "island universe" model, in which galaxies are objects external to the Milky Way rather than components within it, two or three years before Hubble's discovery of Cepheid variable stars in M31 made it formally conclusive.
Also, NGC 584 is not now classified as a spiral but as a lenticular (S0) galaxy, which has a disk like a spiral but no gas or dust and hence no star formation, young stars, or spiral structure, or as an elliptical galaxy. Its modern radial velocity is 1,802 km/sec, or 0.006 times the speed of light, which is miniscule by today's standards.
Jan 18, 2003 - Wildfire destroys the Mount Stromlo Observatory in Australia, a few miles west of Canberra. At least six telescopes were lost and their domes gutted, including an historic 9-inch refractor installed in 1910. The main administration building, library, and workshops were also destroyed, including a $5 million imaging spectrograph almost ready to be sent to the 8-meter Gemini telescope on Mauna Kea, Hawaii. Staff on the mountain had barely tens of minutes to evacuate. Total loss was estimated at $20 million.
Jan 19, 2006 - launch of the New Horizons spacecraft, which flew by Pluto on Jul 14, 2015, and the Kuiper Belt object 2014 MU69 (Ultima Thule) on Jan 1, 2019.
Jan 22, 1867 - Jérôme Eugène Coggia at the Marseilles Observatory discovers what is now known as Comet Stephan-Oterma/P38, initial credit going to the observatory director, Édouard Stéphan, who confirmed the comet two nights later and issued the discovery announcement. The comet's period at that time was only determined to be about three dozen years, with a ±10% accuracy, so it was not observed at its second apparition at the end of 1904 and the beginning of 1905. It was rediscovered in Nov 1942 at the Turku Observatory by Liisi Oterma, the first woman in Finland to get a Ph.D. in astronomy. Observations in 1980 refined the orbital period to 37.96 years, so it will again pass perihelion on Nov 10, 2018.
Jan 23, 1870 - A fireball over the village of Nedagolla, India, leaves behind 9 pounds of meteorite. The meteorite, classified as an "ungrouped iron", has an unusual composition. Recent isotopic analysis suggests it may be the result of a high speed collision between two bodies which formed in different parts of the Sun's protoplanetary disk, accounting for its intermediate composition.
Jan 24, 1986 - The US's Voyager 2 is the first spacecraft to flyby Uranus.
Jan 24, 1985 - The first person to visually observe Halley's Comet on its 1986 return was U.S. amateur astronomer Stephen James O'Meara, using a home-built 24-inch telescope on top of Mauna Kea (and breathing bottled O₂, IIRC) to detect the magnitude 19.6 comet. The aperture size (600mm) gives a light gathering capacity gain of 10 magnitudes over the dark adapted naked eye (6mm), so this observation implies it was equivalent to an unaided eye visual limiting magnitude of 9.6.
Jan 26, 1948 - First light for the Mount Palomar Hale 5-meter / 200" telescope. The star cluster NGC 2261 was observed. At right: the 20 ton mirror blank cast in 1934 at Corning Glass Works before grinding and polishing.
It was five nights later (1/31) that the first test photos were taken. Problems with the mirror's figure and mounting meant that it was over twenty more months later before the first serious research observing run by an astronomer was scheduled. (See Nov 12th)
Jan 26, 1978 - Launch of the IUE, the International Ultraviolet Explorer, a combined project of NASA, the UK-SRC (Science Research Council), and the ESA (European Space Agency).
Though only a 17.7" telescope -- the primary was made of beryllium -- the IUE was the first orbiting observatory to be operated in real time from a ground control terminal by the observing astronomer; this required it to be in a geo-synchronous orbit.
The IUE only did spectroscopy, in two wavelength bands (1150-2000Å and 1850-3300Å) and at two different resolutions (0.2 and 6 Å), and with two different sized entrance apertures (3 arc-seconds and 10x20 arc-seconds), though it did send down visual TV pictures for field acquisition/location and pointing to desired objects in real time.
The telescope was initially given only a three year mission (and five years of fuel), but this ended up being extended to ~6x this long, with funding finally running out in Sep 1996 -- even though by then five of its six gyros had failed, and many of the 100,000 observations it made could be done much more quickly (and better) by the Hubble Space Telescope and other UV-capable orbiting observatories.
Jan 26, 2023 - [00:27 UT on the 27th] The 5 meter sized asteroid 2023 BU, discovered only five days earlier, makes the closest approach ever of an earth-crossing asteroid, at barely 2,200 miles above the surface.
Jan 31, 1862 - Alvan Graham Clark, Jr. discovers the faint white dwarf companion of Sirius, dubbed Sirius B or the Pup, during testing of an 18-inch refractor being built for the Dearborn Observatory by his father, brother, and himself. Friedrich Wilhelm Bessel had proposed the existence of an unseen companion in 1844, based on a "wobble" in the position of Sirius.
Sirius B is 10 full magnitudes fainter than Sirius A, causing the former to be lost in the glare of the latter. The two orbit each other with a period of 50 years. The term "white dwarf" itself would not exist for another sixty years, as it awaited the realization that some very hot, spectral type A stars -- like Sirius B -- could be intrinsically faint and thus very small in size.
Jan 31, 1958 - The first successful U.S. satellite, Explorer 1, is launched.

©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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