2000 SG344

2000 SG344
2000 SG344 seen on 29 September 2000, as a dim streak in the center of the image, moving against the background field of stars
Discovery[1]
Discovered byD. J. Tholen
R. J. Whiteley
Discovery siteMauna Kea Obs.—UH88
Discovery date29 September 2000
(first observation only)
Designations
NEO · Aten
Orbital characteristics[2]
Epoch 2020-May-31 (JD 2457400.5)
Uncertainty parameter 3
Observation arc507 days (1.39 yr)
Aphelion1.0429 AU (156.02 Gm)
Perihelion0.91199 AU (136.432 Gm)
0.97744 AU (146.223 Gm)
Eccentricity0.06696
0.97 yr (352.96 d)
35.680°
1.0198°/day
Inclination0.112202°
191.91°
275.35°
Earth MOID0.0008 AU (120,000 km)
Physical characteristics
37 m (assumed)[3]
15–70 meters[4]
Mass7.1×107 kg (assumed)[3]
24.7[2]

2000 SG344 is a small Aten asteroid first observed in 2000. It is assumed to have a diameter of approximately 37 meters (120 feet) – or roughly twice that of the Chelyabinsk meteor – and an assumed mass of 7.1×107 kg (71,000 tonnes),[3] but the size is only known within about a factor 2. It is the largest object known to have a better than 1/1000 chance (0.1%) of impacting Earth and has the fourth highest cumulative Palermo rating at −2.79. The next good chance to observe the object will be in May 2028 when it passes 0.02 AU (3,000,000 km; 1,900,000 mi) from Earth.[2]

Because of its very Earth-like orbit and because it would have been near the Earth in 1971 (coinciding with the Apollo program), there was speculation that 2000 SG344 might not be an asteroid but a man-made object such as an S-IVB booster stage from a Saturn V rocket which would make it about 15 meters in diameter and much less massive.[4][5] (cf. J002E3, the S-IVB booster of Apollo 12 which was mistaken for an asteroid.)

Upcoming Earth approaches
Date & time Nominal distance uncertainty
region
(3-sigma)
2028-May-07 03:32 ± 4 minutes 2931689 km[2] ± 46000 km[6]
2030-Sep-22 22:36 ± 10 hours 5121080 km[2] ± 380000 km[7]
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  2. ^ a b c d e Cite error: The named reference jpldata was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference nasa-risk-2000sg344 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference NASA was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference Chodas-2001 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference Horizons2028 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Horizons2030 was invoked but never defined (see the help page).