It was discovered on 24 March 1931, by American astronomer Carl Otto Lampland at Lowell Observatory in Flagstaff, Arizona, in the United States.

[2] Tombaugh is a member of the Eos family that orbits the Sun in the outer main-belt at a distance of 2.7–3.3 AU once every 5 years and 3 months (1,920 days).

Lightcurve analysis gave a rotation period of 7.047 and 7.056 hours with a brightness variation of 0.16 and 0.35 magnitude, respectively (U=2+/2+).

[8][9] These periods supersede previous results obtained by astronomers Claes-Ingvar Lagerkvist (1975), Richard P. Binzel (1984) and Krisztián Sárneczky (U=1/2/2).

[4][5] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0933 and a diameter of 32.25 kilometers with an absolute magnitude of 10.65.