||This article's introduction may be too long for its overall length. (July 2011)|
||This article needs additional citations for verification. (July 2011)|
Gehrels, who was born at Haarlemmermeer, the Netherlands, pioneered the first photometric system of asteroids in the 1950s, and wavelength dependence of polarization of stars and planets in the 1960s, each resulting in an extended sequence of papers in the Astronomical Journal.
He discovered, jointly with the husband and wife team of Cornelis Johannes van Houten and Ingrid van Houten-Groeneveld, over 4000 asteroids, including Apollo asteroids, Amor asteroids, as well as dozens of Trojan asteroids. That was done in a sky survey using the 48-inch Schmidt telescope at Palomar Observatory and shipping the plates to the two Dutch astronomers at Leiden Observatory, who analyzed them for new asteroids. The trio are jointly credited with several thousand discoveries. Gehrels also discovered a number of comets.
* in 1889 by Swift, rediscovered
Gehrels initiated the Space Science Series of textbooks, which are at the most advanced level, was General Editor for the first 30 volumes of the University of Arizona Press, and set the style by participating in the editing of six of them. He also initiated the Spacewatch program and was its Principal Investigator (PI) for electronic surveying to obtain statistics of asteroids and comets, including near-Earth asteroids. Bob McMillan was co-investigator and manager, and became the PI in 1997.
Gehrels taught an undergraduate course for non-science majors in Tucson in the Fall, and lectured a brief version of that in the Spring at the Physical Research Laboratory in Ahmedabad, India, where he was a lifetime Fellow. That is in a UN Course for graduate students from countries as Uzbekistan and North Korea, for example.
His recent research was on universal evolution, which was woven in as the guiding thread through these courses. He was the named winner of the 2007 Harold Masursky Award for his outstanding service to planetary science.
Gehrels was requested by the Journal Nature to write a review on a book regarding Wernher von Braun, in which he quotes inmates of concentration camp Dora. He has therefore charged that von Braun was there regularly and much in charge, and that von Braun bears greater responsibility and guilt than his official biography would imply. Towards the end of the book review it reads: Von Braun needs no phony defense, for he was a great man in his own scientific specialization... What is needed is a more sophisticated historical perspective....
Tom Gehrels was the father of Neil Gehrels, George Gehrels and Jo-Ann Gehrels. He died in Tucson, Arizona.
- Special airborne services in Europe and Far East, 1944-1948.
- B.Sc. astronomy and physics, Leiden University 1951.
- Ph.D. astronomy and astrophysics, Univ. of Chicago, 1956.
- Professor of Planetary Sciences and Astronomy, Univ. of Arizona, 1961–2011.
- Physical Studies of Minor Planets, edited by Tom Gehrels (1971), NASA SP-267
- Planets Stars and Nebulae Studied With Photopolarimetry, edited by Tom Gehrels (1974) Tucson: University of Arizona Press ISBN 0-8165-0428-8
- Jupiter: Studies of the Interior, Atmosphere, Magnetosphere, and Satellites, edited by Tom Gehrels and Mildred Shapley Matthews (1976) Tucson: University of Arizona Press ISBN 0-8165-0530-6
- Protostars & Planets: Studies of Star Formation and of the Origin of the Solar System, edited by Tom Gehrels and Mildred Shapley Matthews (1978) Tucson: University of Arizona Press ISBN 0-8165-0674-4
- Asteroids, edited by Tom Gehrels and Mildred Shapley Matthews (1979), ISBN 0-8165-0695-7
- Saturn, edited by Tom Gehrels and Mildred Shapley Matthews (1984) Tucson: University of Arizona Press ISBN 0-8165-0829-1
- Asteroids II, edited by Richard P. Binzel, Tom Gehrels, and Mildred Shapely Matthews (1989)Tucson: University of Arizona Press ISBN 0-8165-1123-3
- Hazards Due to Comets and Asteroids, edited by Tom Gehrels, Mildred Shapley Matthews, and A. M. Schumann (1994) Tucson: University of Arizona Press ISBN 0-8165-1505-0
- On the Glassy Sea, in Search of a Worldview, Tom Gehrels (2007, originally published in 1988), ISBN 1-4196-8247-4
- Survival Through Evolution: From Multiverse to Modern Society, Tom Gehrels (2007), ISBN 1-4196-7055-7
See also 
- Of Truth and Consequences, Tom Gehrels (1994). Nature 372, 511-512