Jesse Leonard Greenstein (October 15, 1909 – October 21, 2002) was an American

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

. His parents were Maurice G. and Leah Feingold. He earned a Ph.D, with thesis advisor

Donald H. Menzel Donald Howard Menzel (April 11, 1901 – December 14, 1976) was one of the first theoretical astronomers and astrophysicists in the United States. He discovered the physical properties of the solar chromosphere, the chemistry of stars, the atmosp ...

, from

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of highe ...

in 1937, having started there at age 16. Before leaving Harvard, Greenstein was involved in a project with

Fred Lawrence Whipple Fred Lawrence Whipple (November 5, 1906 – August 30, 2004) was an American astronomer, who worked at the Harvard College Observatory for more than 70 years. Amongst his achievements were asteroid and comet discoveries, the " dirty snowball" h ...

to explain

Karl Jansky Karl Guthe Jansky (October 22, 1905 – February 14, 1950) was an American physicist and radio engineer who in April 1933 first announced his discovery of radio waves emanating from the Milky Way in the constellation Sagittarius. He is considered ...

's discovery of

radio wave Radio waves are a type of electromagnetic radiation with the longest wavelengths in the electromagnetic spectrum, typically with frequencies of 300 gigahertz ( GHz) and below. At 300 GHz, the corresponding wavelength is 1 mm (sho ...

s from the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...

and to propose a source. He began his professional career at

Yerkes Observatory Yerkes Observatory ( ) is an astronomical observatory located in Williams Bay, Wisconsin, United States. The observatory was operated by the University of Chicago Department of Astronomy and Astrophysics from its founding in 1897 to 2018. Owner ...

under

Otto Struve Otto Struve (August 12, 1897 – April 6, 1963) was a Russian-American astronomer of Baltic German origins. In Russian, his name is sometimes given as Otto Lyudvigovich Struve (Отто Людвигович Струве); however, he spent most o ...

and later went to

Caltech The California Institute of Technology (branded as Caltech or CIT)The university itself only spells its short form as "Caltech"; the institution considers other spellings such a"Cal Tech" and "CalTech" incorrect. The institute is also occasional ...

. With Louis G. Henyey he invented a new

spectrograph An optical spectrometer (spectrophotometer, spectrograph or spectroscope) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify mate ...

and a wide-field camera. He directed the Caltech astronomy program until 1972 and later did classified work on military

reconnaissance satellite A reconnaissance satellite or intelligence satellite (commonly, although unofficially, referred to as a spy satellite) is an Earth observation satellite or communications satellite deployed for military or intelligence applications. Th ...

s. With Leverett Davis, Jr, he demonstrated in 1949 that the magnetic field in our galaxy is aligned with the spiral arms. His theoretical work with Davis was based on the conclusion just reached by William A. Hiltner that the recently detected polarization of starlight was due to scattering off interstellar dust grains aligned by a magnetic field. Greenstein did important work in determining the abundances of the elements in stars, and was, with

Maarten Schmidt Maarten Schmidt (28 December 1929 – 17 September 2022) was a Dutch-born American astronomer who first measured the distances of quasars. He was the first astronomer to identify a quasar, and so was pictured on the March cover of ''Time'' mag ...

, among the first to recognize

quasar A quasar is an extremely luminous active galactic nucleus (AGN). It is pronounced , and sometimes known as a quasi-stellar object, abbreviated QSO. This emission from a galaxy nucleus is powered by a supermassive black hole with a mass rangi ...

s as compact, very distant sources as bright as a galaxy. The spectra of the first quasars discovered, radio sources

3C 48 3C48 is a quasar discovered in 1960; it was the second source conclusively identified as such. 3C48 was the first source in the Third Cambridge Catalogue of Radio Sources for which an optical identification was found by Allan Sandage and Thoma ...

and

3C 273 3C 273 is a quasar located in the constellation of Virgo. It was the first quasar ever to be identified. It is the optically brightest quasar in the sky from Earth ( m ~12.9), and one of the closest with a redshift, ''z'', of 0.158. A lumino ...

, were displaced so far to the red due to their

redshifts 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 simultaneous increase in f ...

as to be almost unrecognizable, but Greenstein deciphered 3C 48 shortly before Schmidt, his colleague at the

Hale Observatories The Hale Observatories are observatories set up by George Ellery Hale, including: * Mount Wilson Observatory, in Los Angeles County, California * Palomar Observatory, in San Diego County, California * Yerkes Observatory, in Williams Bay, Wisconsi ...

worked out the spectrum of 3C 273.

Honors

Awards *

Henry Norris Russell Lectureship The Henry Norris Russell Lectureship is awarded each year by the American Astronomical Society in recognition of a lifetime of excellence in astronomical research. The idea for the lectureship came from then society President Harlow Shapley in 1945, ...

of the American Astronomical Society (1970) *

Bruce Medal The Catherine Wolfe Bruce Gold Medal is awarded every year by the Astronomical Society of the Pacific for outstanding lifetime contributions to astronomy. It is named after Catherine Wolfe Bruce, an American patroness of astronomy, and was fi ...

(1971) *

Gold Medal of the Royal Astronomical Society The Gold Medal of the Royal Astronomical Society is the highest award given by the Royal Astronomical Society (RAS). The RAS Council have "complete freedom as to the grounds on which it is awarded" and it can be awarded for any reason. Past awar ...

(1975) *Golden Plate Award of the

American Academy of Achievement The American Academy of Achievement, colloquially known as the Academy of Achievement, is a non-profit educational organization that recognizes some of the highest achieving individuals in diverse fields and gives them the opportunity to meet ...

(1980)

Honors

* Elected to the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (abbreviation: AAA&S) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, a ...

(1954) * Elected to the United States National Academy of Sciences (1957) * Elected to the

American Philosophical Society The American Philosophical Society (APS), founded in 1743 in Philadelphia, is a scholarly organization that promotes knowledge in the sciences and humanities through research, professional meetings, publications, library resources, and communit ...

(1968) Named after him * Asteroid 4612 Greenstein

References

External links

Obituary from Caltech

Caltech oral history interview

{{DEFAULTSORT:Greenstein, Jesse 1909 births 2002 deaths American astronomers Jewish astronomers Harvard University alumni California Institute of Technology faculty Recipients of the Gold Medal of the Royal Astronomical Society Members of the American Philosophical Society