| Discovery | |
|---|---|
| Discovered by | A. E. Thatcher |
| Discovery date | April 5, 1861 |
| Designations | |
| 1861 I | |
| Orbital characteristics | |
| Observation arc | 149 days |
| Number of observations | 187 |
| Orbit type | Long period comet |
| Aphelion | 112 AU[1] (beyond Eris) |
| Perihelion | 0.921 AU (1861) 0.917 AU (2283)[2] |
| Semi-major axis | 56.3 AU |
| Eccentricity | 0.983 |
| Orbital period | 422 yr (barycentric)[1] |
| Inclination | 79.77° |
| Last perihelion | 1861-Jun-03[3] |
| Next perihelion | 2283 ±5[2] |
Comet C/1861 G1 (Thatcher) is a long-period comet with roughly a 422-year orbit that is expected to return around 2283. It was discovered by A. E. Thatcher. It is responsible for the April Lyrid meteor shower.[4] Carl Wilhelm Baeker also independently found this comet. The comet passed about 0.335 AU (50.1 million km; 31.1 million mi) from the Earth on 5 May 1861 and last came to perihelion (closest approach to the Sun) on 3 June 1861.[3]
C/1861 G1 is listed as a long-period "non-periodic comet" because it has not yet been observed at two perihelion passages. When it is seen to come back around 2283,[2] it should receive the P/ designation.
The comet is the parent body of the April Lyrids meteor shower.
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