|Discovered by||Mount Lemmon Srvy.|
|Discovery site||Mount Lemmon Obs.|
|Discovery date||5 September 2010|
|NEO · Apollo |
|Orbital characteristics |
|Epoch 27 April 2019 (JD 2458600.5)|
|Uncertainty parameter 3 · 4|
|Observation arc||5 days|
|1.09 yr (399 d)|
|0° 54m 9s / day|
|Earth MOID||0.00051 AU (76 thousand km; 0.20 LD)|
6–12 meters (CNEOS)
2010 RF12 is a very small asteroid, classified as near-Earth object of the Apollo group, that passed between Earth and the Moon on 8 September 2010, at 21:12 UTC, approaching Earth within 79,000 kilometres (49,000 mi) above Antarctica. It is listed on the Sentry Risk Table as the asteroid with the greatest known probability (5%) of impacting Earth.[note 1] On 5 September 2096 the asteroid will approach the Earth and the line of variation (LOV) passes through where the Earth will be. The asteroid was discovered by the Mount Lemmon Survey near Tucson, Arizona on 5 September 2010 along with 2010 RX30.
|2095-09-05 23:46||22||0.0002719 AU (40.68 thousand km)||±770 thousand km|
|2096-09-04 21:50||13000||1.05 AU (157 million km)||±2 billion km|
NASA's Near Earth Program estimates its size to be 7 meters (23 feet) in diameter with a mass of around 500 tonnes. 2010 RF12 will make many more close approaches to Earth, with the approach of 5–6 September 2095 having a 4.6% chance (1 in 22) of colliding with Earth. The nominal JPL Earth approach in 2095 is 0.00026 AU (39,000 km; 24,000 mi) with Earth having a radius of approximately 6,400 kilometres (4,000 mi). The nominal NEODyS orbit has the asteroid passing 0.00022 AU (33,000 km; 20,000 mi) from Earth on 6 September 2095, with an apparent magnitude of ~12. Due to the asteroid's relatively small size, there is very little danger of harm arising from such an impact; rather there would be an impressive fireball as the rock air bursts in the upper atmosphere and pebble sized fragments would likely fall to the ground at terminal velocity. The power of the airburst would be somewhere between the 2–4 m Sutter's Mill meteorite and the 17 m Chelyabinsk meteor.
2010 RF12 should be recoverable around its early August 2022 opposition and before the 23 September close approach of about 0.07 AU (10,000,000 km; 6,500,000 mi). It will reach an apparent magnitude of +24.0 to +24.7, and its position will have an uncertainty of roughly 10 arcminutes, 1/3rd the size of the full moon and within the field of view of imaging cameras on large telescopes. It should be detectable during that approach by telescopes of least 2 meters diameter in good observing sites, and the improvement of the orbit from the precise August 2022 position will verify or rule out possible future impacts for the next century or so.