21316

21316 is a minor planet orbiting the Sun in the main asteroid belt. It was discovered on 15 July 1995 by the Lincoln Near-Earth Asteroid Research (LINEAR) project at the Lincoln Laboratory's Experimental Test Site in Socorro, New Mexico. The provisional designation of the object was 1995 OU₂, but it was later given the permanent number 21316 after its orbit was well determined.

The asteroid follows a typical S‑type orbit within the inner part of the main belt. Its semi-major axis is approximately 2.32 astronomical units, with an orbital period of about 3.5 Earth years. The orbit has a low eccentricity of roughly 0.08 and an inclination of about 4 degrees relative to the ecliptic.

Physical estimates for 21316 indicate a diameter of roughly 4.5 kilometers, derived from the measured absolute magnitude and an assumed albedo typical of stony asteroids. No spacecraft missions have visited the object to date, and its rotation period and pole orientation remain uncertain.

In astronomical catalogues 21316 is often referenced by its numeric designation rather than a name, as it has not yet been formally named. The Minor Planet Center lists it among thousands of small solar‑system bodies that have been discovered and tracked over the past few decades.