12973 Melanthios
12973 Melanthios (provisional designation 1973 SY₁) is a Jupiter Trojan asteroid, a body that shares Jupiter's orbit around the Sun in the leading Greek camp at the L4 Lagrange point (gravitationally stable spot 60° ahead of Jupiter).
| Key fact | Detail |
|---|---|
| Designation | 12973 Melanthios, provisional 1973 SY₁2 |
| Orbit | Semi-major axis 5.119 AU, eccentricity 0.0585, inclination 5.75°1 |
| Orbital period | 4,230 days (11.58 years), from 4.82 AU at perihelion to 5.42 AU at aphelion1 |
| Size | About 16.7 km by one estimate; minor-planet catalogs list 28 km1 |
| Hazard status | Not classified as potentially hazardous; no close approaches to Earth1 |
Orbit and classification
Its orbit has a semi-major axis of 5.119 AU, an eccentricity of 0.0585, and an inclination of 5.75 degrees to the ecliptic.1 One circuit of the Sun takes 4,230 days, or 11.58 years, with the distance from the Sun varying between 4.82 AU at perihelion and 5.42 AU at aphelion; its average orbital speed is 13.17 km/s.1
The orbit is well determined. The Minor Planet Center records 1,966 observations, with the observation arc extending from the discovery date of 19 September 1973 to the most recent official observation on 1 April 2023.1
Physical characteristics
Estimates of the asteroid's size differ by source. A diameter of about 16.7 km is derived from its brightness and assumed reflectivity, while the compiled minor-planet catalogs list 28 km.1 The spread reflects the uncertainty introduced by an assumed albedo, since a body that reflects more light can be smaller and still appear equally bright. Its absolute magnitude is 11.56.1
Earth-approach status
Melanthios is not a near-Earth object and has not been classified as potentially hazardous. Its orbit stays at least 3.83 AU from Earth's orbit at their closest points, and orbital simulations by NASA JPL's Center for Near-Earth Object Studies show no close approaches to Earth. It is also not considered a viable target for human exploration by the NHATS study.1
References
- Asteroid 12973 Melanthios (1973 SY1), Space Reference
- (12973) Melanthios = 1996 SY7 = 1973 SY1, IAU Minor Planet Center
Topic: Encyclopedia › Places and geography › Extraterrestrial places › Small bodies of the Solar System › Jupiter Trojans and other dynamical groups › Greek-camp Jupiter Trojans › Heroes of the Odyssean circle
Initially written Oct 21, 2026 · Edited: Oct 25, 2026
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