Discovered by LONEOS MPC designation (101869) 1999 MM Minor planet category Apollo · NEO · PHA Discovered 20 June 1999 Discovery site Anderson Mesa Station | Discovery date 20 June 1999 Alternative names 1999 MM Observation arc 8.67 yr (3,167 days) Absolute magnitude 19.3 Asteroid group Apollo asteroid | |
Discoverer Lowell Observatory Near-Earth-Object Search | ||
(101869) 1999 MM is an unnamed, eccentric asteroid of the Apollo group, classified as a near-Earth object and potentially hazardous asteroid, approximately half a kilometer in diameter. It was discovered on 20 June 1999, by the Lowell Observatory Near-Earth-Object Search (LONEOS) at its U.S. Anderson Mesa Station in Flagstaff, Arizona. The first observation was made by Catalina Sky Survey just 8 days before its discovery.
The asteroid orbits the Sun at a distance of 0.6–2.6 AU once every 2 years and 1 month (756 days). Its orbit has an eccentricity of 0.61 and an inclination of 5° with respect to the ecliptic.It has a notably low Earth minimum orbit intersection distance of 0.0016 AU (240,000 km), which is less than one lunar distance, and also approaches Mars and Venus to within 15 million kilometers. Its orbit is very similar to that of 69230 Hermes, which in 1937 made what was for decades the closest observed approach to Earth by an asteroid. 1999 MM's nearest pass to Earth within at least a century of present was the 930,000 kilometers one in 1875. In 2090 it passes Venus at 788,000 kilometers.
Based on its absolute magnitude of 19.3, its diameter is between 350 and 900 meters, assuming an albedo in the range of 0.05 to 0.25.