Milton La Salle Humason (August 19, 1891 – June 18, 1972) was an American

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

. He worked with

Edwin Hubble Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology. Hubble proved that many objects previously ...

to measure the

redshift In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and e ...

nebula A nebula (; or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral, or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regions, such as in the Pillars of Creation in ...

s in the early 20th century, providing evidence of the

expansion of the universe The expansion of the universe is the increase in proper length, distance between Gravitational binding energy, gravitationally unbound parts of the observable universe with time. It is an intrinsic and extrinsic properties (philosophy), intrins ...

Biography

Milton Humason was born in Dodge Center,

Minnesota Minnesota ( ) is a U.S. state, state in the Upper Midwestern region of the United States. It is bordered by the Canadian provinces of Manitoba and Ontario to the north and east and by the U.S. states of Wisconsin to the east, Iowa to the so ...

. Humason dropped out of school and had no formal education past the age of 14. Because he loved the mountains, and Mount Wilson in particular, he became a "mule skinner" taking materials and equipment up the mountain while

Mount Wilson Observatory The Mount Wilson Observatory (MWO) is an Observatory#Astronomical observatories, astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson (California), Mount Wilson, a peak in the San Gabrie ...

was being built. In 1917, after a short stint on a ranch in La Verne, he became a

janitor A cleaner, cleanser or cleaning operative is a type of Industry (economics), industrial or domestic worker who is tasked with cleaning a space. A janitor (Scotland, United States and Canada), also known as a custodian, Facility Operator, porter ...

at the observatory. Out of sheer interest, he volunteered to be a night assistant at the observatory. His technical skill and quiet manner made him a favorite on the mountain. Recognizing his talent, in 1919,

George Ellery Hale George Ellery Hale (June 29, 1868 – February 21, 1938) was an American astrophysicist, best known for his discovery of magnetic fields in sunspots, and as the leader or key figure in the planning or construction of several world-leading ...

made him a Mt. Wilson staff member. This was unprecedented, as Humason did not have a Ph.D., or even a high school diploma. He soon proved Hale's judgment correct, as he made several key observational discoveries. He became known as a meticulous observer, obtaining photographs and difficult

spectrogram A spectrogram is a visual representation of the spectrum of frequencies of a signal as it varies with time. When applied to an audio signal, spectrograms are sometimes called sonographs, voiceprints, or voicegrams. When the data are represen ...

s of faint galaxies. His observations played a major role in the development of

physical cosmology Physical cosmology is a branch of cosmology concerned with the study of cosmological models. A cosmological model, or simply cosmology, provides a description of the largest-scale structures and dynamics of the universe and allows study of fu ...

, including assisting

in formulating

Hubble's law Hubble's law, also known as the Hubble–Lemaître law, is the observation in physical cosmology that galaxies are moving away from Earth at speeds proportional to their distance. In other words, the farther a galaxy is from the Earth, the faste ...

. In 1950 he earned a D.Sc. from

Lund University Lund University () is a Public university, public research university in Sweden and one of Northern Europe's oldest universities. The university is located in the city of Lund in the Swedish province of Scania. The university was officially foun ...

. He retired in 1957. He discovered Comet

C/1961 R1 Comet Humason, Astronomical naming conventions#Comets, formally designated C/1961 R1 (a.k.a. 1962 VIII and 1961e), was a List of non-periodic comets, non-periodic comet discovered by Milton L. Humason on 1 September 1961. Its perihelion was well ...

(Humason), notable for its large

perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

distance. Due to merest chance, Humason missed discovering

Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Su ...

. Eleven years before

Clyde Tombaugh Clyde William Tombaugh (; February 4, 1906 – January 17, 1997) was an American astronomer best known for discovering Pluto, the first object to be identified in what would later be recognized as the Kuiper belt, in 1930. Raised on farms in ...

, Humason took a set of four photographs in which the image of Pluto appeared. There is persistent speculation that he missed discovering the dwarf planet because it fell on a defect in the photographic plate. This is unlikely, however, given that it appeared in four separate photographs over three different nights. Much of the work Humason performed was actually credited to Hubble, the two of whom worked together for many years. He died in

Mendocino, California Mendocino (Spanish language, Spanish for "of Antonio de Mendoza, Mendoza") is an Unincorporated area#United States, unincorporated community in Mendocino County, California, United States. The name comes from Cape Mendocino to the north, named b ...

In popular culture

In the popular documentary '' Cosmos: A Personal Voyage'' by astronomer

Carl Sagan Carl Edward Sagan (; ; November 9, 1934December 20, 1996) was an American astronomer, planetary scientist and science communicator. His best known scientific contribution is his research on the possibility of extraterrestrial life, including e ...

, Humason's life and work are portrayed on screen in episode 10: ''The Edge of Forever.'' Humason was also the inspiration for the

Big Dipper The Big Dipper (American English, US, Canadian English, Canada) or the Plough (British English, UK, Hiberno-English, Ireland) is an asterism (astronomy), asterism consisting of seven bright stars of the constellation Ursa Major; six of them ar ...

song "Humason," which appeared on the Boston group's 1987 album Heavens.

Honors

* The crater

Humason Milton La Salle Humason (August 19, 1891 – June 18, 1972) was an American astronomer. He worked with Edwin Hubble to measure the redshift of nebulas in the early 20th century, providing evidence of the expansion of the universe. Biography ...

on the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

is named after him as are " Humason-Zwicky stars".

Cited sources

External links

Obituary

{{DEFAULTSORT:Humason, Milton 1891 births 1972 deaths People from Dodge Center, Minnesota 20th-century American astronomers Discoverers of comets