# (276033) 2002 AJ129

(276033) 2002 AJ$_{129}$, provisional designation 2002 AJ$_{129}$, is a Mercury-crossing asteroid. It has the ninth-smallest perihelion of all numbered asteroids, after asteroids such as 2000 BD$_{19}$, 2004 UL, and 2008 XM. 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 kilometers (0.3–0.7 mi) 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

2002 AJ$_{129}$ 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 (4,207,600 km; 2,614,500 mi) 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 (685,000 km; 426,000 mi) 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 (36,000,000 km; 22,000,000 mi) on 19 February 2196 the uncertainty increases to ±2.4 million km.
| PHA | Date | Approach distance in lunar distances | Approach distance in lunar distances | Approach distance in lunar distances | Abs. mag (H) | Diameter $^{(C)}$ (m) | Ref $^{(D)}$ |
| PHA | Date | Nominal$^{(B)}$ | Minimum | Maximum | Abs. mag (H) | Diameter $^{(C)}$ (m) | Ref $^{(D)}$ |
| (152680) 1998 KJ9 | 1914-12-31 | 0.606 | 0.604 | 0.608 | 19.4 | 279–900 | data |
| (458732) 2011 MD5 | 1918-09-17 | 0.911 | 0.909 | 0.913 | 17.9 | 556–1795 | data |
| (163132) 2002 CU11 | 1925-08-30 | 0.903 | 0.901 | 0.905 | 18.5 | 443–477 | data |
| 69230 Hermes | 1937-10-30 | 1.926 | 1.926 | 1.927 | 17.5 | 700-900 | data |
| 69230 Hermes | 1942-04-26 | 1.651 | 1.651 | 1.651 | 17.5 | 700-900 | data |
| 2017 NM6 | 1959-07-12 | 1.89 | 1.846 | 1.934 | 18.8 | 580–1300 | data |
| (27002) 1998 DV9 | 1975-01-31 | 1.762 | 1.761 | 1.762 | 18.1 | 507–1637 | data |
| 2002 NY40 | 2002-08-18 | 1.371 | 1.371 | 1.371 | 19.0 | 335–1082 | data |
| 2004 XP14 | 2006-07-03 | 1.125 | 1.125 | 1.125 | 19.3 | 292–942 | data |
| 2015 TB145 | 2015-10-31 | 1.266 | 1.266 | 1.266 | 20.0 | 620-690 | data |
| (137108) 1999 AN10 | 2027-08-07 | 1.014 | 1.010 | 1.019 | 17.9 | 556–1793 | data |
| (153814) 2001 WN5 | 2028-06-26 | 0.647 | 0.647 | 0.647 | 18.2 | 921–943 | data |
| 99942 Apophis | 2029-04-13 | 0.0981 | 0.0963 | 0.1000 | 19.7 | 310–340 | data |
| 2017 MB1 | 2072-07-26 | 1.216 | 1.215 | 2.759 | 18.8 | 367–1186 | data |
| 2011 SM68 | 2072-10-17 | 1.875 | 1.865 | 1.886 | 19.6 | 254–820 | data |
| (163132) 2002 CU$_{11}$ | 2080-08-31 | 1.655 | 1.654 | 1.656 | 18.5 | 443–477 | data |
| (416801) 1998 MZ | 2116-11-26 | 1.068 | 1.068 | 1.069 | 19.2 | 305–986 | data |
| (153201) 2000 WO107 | 2140-12-01 | 0.634 | 0.631 | 0.637 | 19.3 | 427–593 | data |
| (276033) 2002 AJ129 | 2172-02-08 | 1.783 | 1.775 | 1.792 | 18.7 | 385–1242 | data |
| (290772) 2005 VC | 2198-05-05 | 1.951 | 1.791 | 2.134 | 17.6 | 638–2061 | data |
| $^{(A)}$ This list includes near-Earth approaches of less than 2 lunar distances (LD) of objects with H brighter than 20. $^{(B)}$ Nominal geocentric distance from the center of Earth to the center of the object (Earth has a radius of approximately 6,400 km). $^{(C)}$ Diameter: estimated, theoretical mean-diameter based on H and albedo range between X and Y. $^{(D)}$ Reference: data source from the JPL SBDB, with AU converted into LD (1 AU≈390 LD) $^{(E)}$ Color codes: unobserved at close approach observed during close approach upcoming approaches ||||||||