(155140) 2005 UD

(155140) 2005 UD (provisional designation 2005 UD) is an asteroid on an eccentric orbit, classified as a near-Earth object of the Apollo group. It was discovered on 22 October 2005, by the Catalina Sky Survey at the Catalina Station in Arizona, United States. 2005 UD is thought to be a possible fragment of 3200 Phaethon due to its similar orbit, although it is not dynamically associated with the Geminid meteor stream produced by Phaethon.

Due to 2005 UD's highly eccentric orbit, it experiences extreme temperature variations up to 975 K at perihelion, leading to thermal fracturing of its surface regolith and ejection of dust particles. However, no activity from 2005 UD has been observed as of yet, though it has been suspected that it could be the inactive parent body of the Daytime Sextantids meteor shower. 2005 UD and Phaethon share a bluish surface color at visible wavelengths, but differ at near-infrared wavelengths where 2005 UD appears redder than Phaethon.

2005 UD will pass 0.0558 AU from Mars on 20 July 2024.