| Minorplanet: | yes |
| (155140) 2005 UD | |
| Background: |
|
| Discovered: | 22 October 2005 |
| Mpc Name: | 2005 UD |
| Epoch: | 1 July 2020 (JD 2459396.5) |
| Uncertainty: | 0 |
| Observation Arc: | 38.76 yr (14,157 days) |
| Earliest Precovery Date: | 11 November 1982 |
| Perihelion: | 0.1629 AU |
| Semimajor: | 1.275 AU |
| Eccentricity: | 0.8722 |
| Period: | 1.44 yr (525.8 days) |
| Mean Motion: | / day |
| Inclination: | 28.660° |
| Asc Node: | 19.714° |
| Arg Peri: | 207.603° |
| Magnitude: | 17.0 (discovery) |
| Abs Magnitude: | 17.42 |
(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 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 0.0558abbr=unitNaNabbr=unit from Mars on 20 July 2024.
| 6 km | 0.02abbr=unitNaNabbr=unit | 0.14AU | 0.14AU | ||
| (155140) 2005 UD | 1.3 km | 0.08AU | 0.16AU | 0.04AU | |
| (225416) 1999 YC | 1.7 km | 0.25AU | 0.24AU | 0.1AU |