103P/Hartley
| Discovery | |
|---|---|
| Discovered by | Malcolm Hartley |
| Discovery site | Siding Spring, Australia |
| Discovery date | 15 March 1986 |
| Designations | |
| P/1986 E2, P/1991 N1 | |
| |
| Orbital characteristics | |
| Epoch | 5 May 2025 (JD 2460800.5) |
| Observation arc | 20.44 years |
| Number of observations | 8,857 |
| Aphelion | 5.89 AU |
| Perihelion | 1.06 AU |
| Semi-major axis | 3.48 AU |
| Eccentricity | 0.694 |
| Orbital period | 6.48 years |
| Inclination | 13.608° |
| 219.76° | |
| Argument of periapsis | 181.33° |
| Mean anomaly | 86.789° |
| Last perihelion | 12 October 2023 |
| Next perihelion | 5 April 2030 |
| TJupiter | 2.642 |
| Earth MOID | 0.072 AU |
| Jupiter MOID | 0.277 AU |
| Physical characteristics | |
| Dimensions | 1.2–1.6 km (0.75–0.99 mi) |
| Mass | 300 megatonnes (3.0×1011 kg; 6.6×1011 lb) |
| 18.1 hours | |
| 0.028 | |
| Comet total magnitude (M1) | 16.0 |
Comet Hartley 2, designated as 103P/Hartley by the Minor Planet Center, is a small periodic comet with an orbital period of 6.48 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit, Siding Spring Observatory, Australia. Its diameter is estimated to be 1.2–1.6 km (0.75–0.99 mi)
Hartley 2 was the target of a flyby of the Deep Impact spacecraft, as part of the EPOXI mission, on 4 November 2010, which was able to approach within 700 km (430 mi) of Hartley 2 as part of its extended mission. As of November 2010 Hartley 2 is the smallest comet which has been visited. It is the fifth comet visited by spacecraft, and the second comet visited by the Deep Impact spacecraft, which first visited comet Tempel 1 on 4 July 2005.