9965 GNU – An asteroid named for the free-software GNU Project

9965 GNU is a main-belt asteroid named in honor of the GNU Project, the free-software initiative launched by Richard Stallman in 1984. Its name reflects GNU’s recursive acronym, “GNU is not Unix,” and the project’s aim of enabling programmers to share and improve software. The asteroid was formally discovered by the Spacewatch program at Kitt Peak Observatory in Arizona on March 5, 1992, though it had been observed earlier at La Silla Observatory in 1988 under a different provisional designation. Its official name was published in 2000.

The asteroid belongs to the background population of the inner belt and orbits the Sun every 3.76 years, traveling between about 2.0 and 2.8 astronomical units from it. Its orbit is moderately eccentric and inclined about 12 degrees to Earth’s orbital plane. Estimates of its diameter vary substantially, from roughly 2 to 6 kilometers; a commonly used calculated estimate is about 4.1 kilometers. Its surface reflectivity is likewise uncertain, and surveys have classified it as either a dark D-type or an S-type asteroid. Observations in 2012 measured a rotation period of about 39.7 hours, considerably longer than the typical 2-to-20-hour spin period of most asteroids.