Tom Gehrels

Tom Gehrels
Gehrels at Spacewatch Telescope 1980's
Born	(1925-02-21)February 21, 1925 Haarlemmermeer, the Netherlands
Died	July 11, 2011(2011-07-11) (aged 86) Tucson, Arizona, United States
Nationality	Dutch–American
Occupation	Astronomer

Anton M.J. "Tom" Gehrels (February 21, 1925 – July 11, 2011) was a Dutch–Americanastronomer, Professor of Planetary Sciences, and Astronomer at the University of Arizona, Tucson.

Gehrels was born at Haarlemmermeer, the Netherlands on February 21, 1925. During World War II he was, as a teenager, active in the Dutch Resistance. After he escaped to England, he was sent back by parachute as an organizer for Special Operations Executive SOE committing sabotage against the German forces.

After the war, he attended the University of Leiden where he graduated with a degree in physics and astronomy in 1951. He continued his education at the University of Chicago where he obtained his doctorate in astronomy and astrophysics in 1956 under Professor Hamza. In 1960, he moved to the University of Arizona along with Gerard Kuiper where he would remain for the next 50 years.

Gehrels 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.