(33342) 1998 WT₂₄ - Low Aphelion

Low Aphelion

(33342) 1998 WT₂₄ was discovered on November 25, 1998, by LINEAR about four months after a particularly close encounter with the planet Mercury (about 0.047 au). At the time of its discovery, astronomers were trying to find the first Apohele asteroid (one that is always closer to the Sun than the Earth). All asteroids known at the time that got closer to the Sun than the Earth also crossed Earth's orbit. Earlier that year, David J. Tholen claimed to have spotted the first Apohele asteroid, which was dubbed 1998 DK₃₆. However, the object was lost without being confirmed. Thus, 1993 DA remained the asteroid with the lowest known aphelion at 1.023 au. When 1998 WT₂₄ was discovered, it was found to have a slightly smaller aphelion than 1993 DA (1.019 au), and was thus the closest thing to an Apohele asteroid known at the time. It lost its smallest aphelion title almost immediately when 1998 XX₂ was discovered only a few weeks later (aphelion = 1.013 au). Asteroids with even smaller aphelions were discovered until February 2003, when finally, an asteroid with an aphelion smaller than 1.000 au was discovered. This was (163693) Atira, the first confirmed Apohele asteroid.