(276033) 2002 AJ129

, provisional designation, is a Mercury-crossing asteroid. It has the ninth-smallest perihelion of all numbered asteroids, after asteroids such as, , and. It makes close approaches to all of the inner planets and asteroid 4 Vesta. The asteroid is estimated to be between 0.5 - 1.2 km across. In January 2018 there was much media hype about this asteroid being classified as a potentially hazardous asteroid, although there is no known threat of an impact for hundreds if not thousands of years. The media has compared the size of the asteroid to the Burj Khalifa in Dubai.

Description
was discovered on 15 January 2002 by astronomers of the NEAT team at Haleakala Observatory, Hawaii, United States. It was removed from the Sentry Risk Table on 3 February 2002.

It is a Mercury-, Venus-, Earth- and Mars-crossing asteroid. With an observation arc of 14 years, it has a well determined orbit and was last observed in 2016. It is classified as an Apollo asteroid because it is a near-Earth asteroid with a semi-major axis larger than Earth's. It is also categorized as a potentially hazardous asteroid, but that does not mean there is a near-term threat of an impact. It is a potentially hazardous asteroid merely as a result of its size (absolute magnitude H ≤ 22) and Earth minimum orbit intersection distance (Earth MOID ≤ 0.05 AU).

2018 approach
On 4 February 2018 at 21:31 UT, the asteroid passed about 0.028126 AU from Earth. The 2018 Earth approach distance was known with a 3-sigma accuracy of ±200 km. Goldstone is scheduled to observe the asteroid from 3 to 6 February. By 4 February 2018 11:00 UT, the asteroid brightened to apparent magnitude 14 and had a solar elongation of more than 100°.

2172 approach
On 8 February 2172, the asteroid will pass about 0.00458 AU from Earth. The 2172 Earth approach distance is known with a 3-sigma accuracy of ±4000 km.

As we look even further into the future the known trajectory becomes more divergent. By the Earth approach of 0.24 AU on 19 February 2196 the uncertainty increases to ±2.4 million km.