Jesse L. Greenstein

Jesse Leonard Greenstein (October 15, 1909 – October 21, 2002) was an American astronomer. His parents were Maurice G. and Leah Feingold.

He earned a Ph.D from Harvard University in 1937. Before leaving Harvard, Greenstein was involved in a project with Fred Lawrence Whipple to explain Karl Jansky's discovery of radio waves from the Milky Way and to propose a source.^[1] He began his professional career at Yerkes Observatory under Otto Struve and later went to Caltech. With Louis G. Henyey he invented a new spectrograph and a wide-field camera. He directed the Caltech astronomy program until 1972 and later did classified work on military reconnaissance satellites.

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 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, the first to recognize quasars as compact, very distant sources as bright as a galaxy. The spectra of the first quasars discovered, radio sources 3C 48 and 3C 273, were displaced so far to the red due to their redshifts as to be almost unrecognizable, but Greenstein deciphered 3C 48 shortly before Schmidt, his colleague at the Hale Observatories worked out the spectrum of 3C 273.

Honors

Awards

• Henry Norris Russell Lectureship of the American Astronomical Society (1970)
• Bruce Medal (1971)
• Gold Medal of the Royal Astronomical Society (1975)

Named after him

• Asteroid 4612 Greenstein

References

1. ^ Jessie L. Greenstein, Optical and Radio Astronomers in the Early Years. In Sullivan, Woodruff T. (2005). The Early Years of Radio Astronomy: Reflections Fifty Years After Jansky's Discovery. Cambridge University Press.  pp. 67-82

External links

• Obituary from Caltech
• Caltech oral history interview
• Story of the discovery of quasars
• Bruce Medal page
• Awarding of Bruce medal: PASP 83 (1971) 243
• Awarding of RAS gold medal: QJRAS 16 (1975) 356
• Biography by Robert P. Kraft, former director of Lick Observatory

Persondata
Name	Greenstein, Jesse
Alternative names
Short description
Date of birth	October 15, 1909
Place of birth
Date of death	October 21, 2002
Place of death