On Sunday 22 July 2012 the asteroid 2002 AM₃₁ flew past the Earth at a distance of 5.2 million km. This is a fairly safe distance, nearly 14 times as far from us as the Moon, but it will give scientists a chance to try to examine the object, which is currently not well known; estimates of the size of 2002 AM₃₁ vary from 340 m to 1.4 km in diameter, with corresponding variations in the estimation of its mass.
The orbit of 2002 AM₃₁. JPL.
2002 AM₃₁ was discovered in 2002 by Lincoln Near Earth Asteroid Research and is considered to be potentially hazardous by the Minor Planet Center. It takes 812 days (2.22 years) to complete one orbit about the Sun, during which time it will fall to 0.934 AU of the Sun (slightly inside the orbit of the Earth, which orbits the Sun at an average of 1.0 AU) then rise to 2.47 AU, considerably outside the orbit of Mars. This means that it crosses the orbits of both the Earth and Mars during each of its orbits, but it does not necessarily come close to the planets when it does so. 2002 AM₃₁ last came this close to the Earth in July 1923, and it will next do so in July 2032. There is no danger of a collision with the Earth in the next 200 years.
See also The Earth reaches its aphelion, 2012 LZ1; bigger than we thought, Asteroid 2012 LZ1 flies by the Earth, The origin of Comet P/2006 VW₁₃₉ and Asteroid 2012 KP24 passes Earth at a distance of 51 000 km.
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