Takeshi Oka (? ??, Oka Takeshi, born 1932), , is a Japanese-American chemist and astronomer specializing in the field of galactic astronomy, known as the pioneer of astrochemistry and the discoverer of extraterrestrial trihydrogen cation (H+3).He is now R.A.
Milliken Distinguished Service Emeritus Professor, Departments of Astronomy and Astrophysics, Chemistry; Enrico Fermi Institute; and the College of University of Chicago.