(20729) Opheltius Jupiter Trojan
Discovered on 15 December 1999 by C. W. Juels at Fountain Hills.
Opheltius was an Achean killed by Hector. Another character of the same name fought as a defender of Troy.Naming citation (WGSBN Bull. 5, #5, 22), IAU / Minor Planet Center, via NASA/JPL
Where Opheltius is today
Seen from above the solar system on 2026-10-14: Opheltius is 5.52 au from the Sun and 6.45 au from Earth. Computed from JPL's orbital elements.
Facts
| Number | 20729 |
| Provisional designation | 1999 XS143 |
| Orbit class | Jupiter Trojan |
| Diameter | 51.0 km (#724 largest of 17,440 named asteroids with a measured size) |
| Albedo | 0.0520 |
| Rotation period | 5.72 hours |
| Absolute magnitude (H) | 10.5 |
| Orbital period | 11.9 years |
| Semi-major axis | 5.22 au |
| Perihelion – aphelion | 4.89 – 5.56 au |
| Eccentricity | 0.0642 |
| Inclination | 22.0° |
| Closest distance between its orbit and Earth's (MOID) | 3.99 au |
Data: NASA/JPL Small-Body Database and the IAU Minor Planet Center.