Following the Soviet occupation of Estonia in 1944, Toomre and his family fled to Germany; they emigrated to the United States in 1949.

He received an undergraduate degree in Aeronautical Engineering and Physics from MIT in 1957[2][4] and then studied at the University of Manchester on a Marshall Scholarship where he obtained a Ph.D. in fluid mechanics.

[5] After spending a year at the Institute for Advanced Study,[7] he returned again to MIT as part of the faculty, where he stayed.

[11] Toomre conducted the first computer simulations of galaxy mergers in the 1970s with his brother Jüri, an astrophysicist and solar physicist.

[25] In 1993, Toomre received the Dirk Brouwer Award which recognizes "outstanding contributions to the field of Dynamical Astronomy".