2009 RR micro-asteroid, classified as near-Earth object of the Apollo group.^[2] It was discovered on 11 September 2009 by the Catalina Sky Survey at an apparent magnitude of 19.5 using a 0.68-meter (27 in) Schmidt–Cassegrain telescope.^[1] 2009 RR was the only asteroid discovered before 2014 that was predicted to potentially pass inside the orbit of the Moon during 2014. The asteroid has an estimated diameter of 26 meters (85 ft) and is listed on the Sentry Risk Table.^[3] It is not large enough to qualify as a potentially hazardous object.

With an observation arc of only 4 days, the asteroid has a poorly determined orbit.^[2] It is already known that there is no risk of an Earth impact before 2098.^[3] The power of such an air burst would be somewhere between the Chelyabinsk meteor and the Tunguska event depending on the actual size of the asteroid.

The nominal orbit shows that on 16 September 2014 the asteroid could have passed just inside one lunar distance from Earth,^[4] but the orbital uncertainties show that it could have passed as much as 0.1 AU (15,000,000 km; 9,300,000 mi) from Earth.^[5] On 9 September 2014 the full moon may have only be 15 degrees from the 20th magnitude asteroid, making it difficult to detect the asteroid.^[4] The asteroid was estimated to be brighter than magnitude 20 from 10 September until 16 September 2014.^[4] 2009 RR was not recovered during the 2014 approach and thus probably passed more than one lunar distance from Earth.

• 2009 RR at NeoDyS-2, Near Earth Objects—Dynamic Site
  • Ephemerides · Observation prediction · Orbital info · MOID · Proper elements · Observational info · Close approaches · Physical info · Orbit animation
• 2009 RR at ESA–space situational awareness
  • Ephemerides · Observations · Orbit · Physical properties · Summary
• 2009 RR at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters