2010 RF12

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.^[5] The asteroid was discovered by the Mount Lemmon Survey near Tucson, Arizona on 5 September 2010 along with 2010 RX30.^[1][6] Based on a short 7-day observation arc from that apparation, it was listed for 12 years on the Sentry Risk Table as the asteroid with the greatest known probability (5%) of impacting Earth.^{[7][note 1]} 2010 RF₁₂ was rediscovered in August 2022,^[8][1] and now has a 12-year observation arc and a much better known orbit. As of the December 2022 solution which accounts for nongravitational forces,^[3] there is a 1-in-10 chance of an Earth impact on 5 September 2095.^[4]

Nominal Earth Approach on 6 September 2095 with a 12-year observation arc^[3]

Date	Impact probability	JPL Horizons nominal geocentric distance (AU)	uncertainty region (3-sigma)
2095-09-06 00:06 ± 00:20	1:10	0.00035 AU (52 thousand km)[3]	±180 thousand km[9]

2010 RF₁₂

Discovery[1][2]
Discovered by	Mount Lemmon Srvy.
Discovery site	Mount Lemmon Obs.
Discovery date	5 September 2010
Designations
MPC designation	2010 RF12
Minor planet category	NEO · Apollo[1][3]
Orbital characteristics[3]
Epoch 2025-May-05 (JD 2460800.5)
Uncertainty parameter 0 (MPC)[1] 2 (JPL)[3]
Observation arc	11.98 years
Aphelion	1.261 AU
Perihelion	0.86155 AU
Semi-major axis	1.0615 AU
Eccentricity	0.18834
Orbital period (sidereal)	1.094 yr (399.441 d)
Mean anomaly	85.8°
Mean motion	0° 54m 4.68s / day
Inclination	0.88264°
Longitude of ascending node	163.69°
Time of perihelion	2025-Jan-29[3]
Argument of perihelion	267.43°
Earth MOID	0.00072 AU (108 thousand km; 0.28 LD)
Physical characteristics
Mean diameter	7 m[4] 6–12 meters (CNEOS)
Absolute magnitude (H)	28.4[1][3]

Description

NASA's Near Earth Program estimates its size to be 7 meters (23 feet) in diameter with a mass of around 500 tonnes.^[4] 2010 RF₁₂ will make many more close approaches to Earth.^[3] Around 6 September 2095 it will pass 52000±180000 km from Earth.^[3][9] An asteroid roughly 7-meters in diameter impacting Earth would cause very little danger of harm, but a rather impressive fireball is expected (estimated in the risk table as nearly 9 KT of energy release^[4]) as the rock airbursts in the upper atmosphere. Pebble sized fragments would likely fall to the ground at terminal velocity.^[10] The power of the airburst would be somewhere between the 2–4 m Sutter's Mill meteorite and the 17 m Chelyabinsk meteor (which had 440 KT equivalent energy).^[11] The approach in 2096 is poorly known because it is dependent on the September 2095 Earth approach.

Virtual impactors with a 12-year observation arc^[4]

Date	Impact probability (1 in)	JPL Horizons nominal geocentric distance (AU)	NEODyS nominal geocentric distance (AU)	MPC nominal geocentric distance (AU)	Find_Orb nominal geocentric distance (AU)	uncertainty region (3-sigma)
2095-09-05 23:46	10	0.00035 AU (52 thousand km)	0.0008 AU (120 thousand km)[12]	0.00066 AU (99 thousand km)	0.00087 AU (130,000 km)[13]	±180 thousand km[14]
2096-09-04 21:50	22000	0.84 AU (126 million km)[15]	0.18 AU (27 million km)[16]	0.36 AU (54 million km)	0.19 AU (28 million km)[17]	±414 million km[15]

On 17 February 2059 the asteroid will pass within 3.5 million km from Earth^[3] and reach about apparent magnitude 22.6 by late February. On 10 September 1915 it passed 463000±30000 km from Earth.^[3]

See also

• 2010 RX30, a similar-sized asteroid that passed Earth the same day
• 2000 SG344, another near-Earth asteroid (may be Saturn V stage IV rocket booster)
• 2006 JY26
• Asteroid impact prediction
• List of asteroid close approaches to Earth, for other close approaches
• Earth-grazing fireball
• Meteoroid

Notes

1. Many small and harmless asteroids (less than ~10 meters in diameter) impact Earth every year but very few are discovered and predicted, see Asteroid impact prediction.