121P/Shoemaker–Holt
Periodic comet with an eight-year orbit
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121P/ShoemakerâHolt, also known as Shoemaker-Holt 2, is a periodic comet in the Solar System with an orbital period of about 10 years. The comet was discovered by Carolyn S. Shoemaker, Eugene M. Shoemaker, and Henry E. Holt on 9 March 1989. The comet then had an apparent magnitude of 13, was diffuse and had a tail about 2 arcminutes long.[7] It was recovered by James V. Scotti on 29 August 1995 in images obtained as part of the Spacewatch survey.[8]
| |
| Discovery | |
|---|---|
| Discovered by | Carolyn S. Shoemaker Eugene Merle Shoemaker Henry E. Holt |
| Discovery date | March 9, 1989 |
| Designations | |
| 1989j; 1988 XI; 1995 Q3 | |
| Orbital characteristics | |
| Epoch | 2025-11-21 |
| Aphelion | 5.45 AU |
| Perihelion | 3.73 AU |
| Semi-major axis | 4.59 AU |
| Eccentricity | 0.187 |
| Orbital period | 9.84 yr |
| Inclination | 20.16° |
| Last perihelion | June 28, 2023[1] September 8, 2013[2] September 1, 2004 |
| Next perihelion | 2033-May-05[3] |
| Physical characteristics[4][5][6] | |
Mean radius | 3.61 km (2.24 mi) |
| ~10 hours | |
| (VâR) = 0.53±0.03 | |
The nucleus of the comet is estimated to have a radius of 3.87 km based on infrared imaging by the Spitzer Space Telescope, when the comet displayed dust emission.[5] Observations of the comet from the Isaac Newton Telescope indicate an effective radius of 3.61 kilometers. The rotational period was calculated to be 10 hours, but with high uncertainty.[4]
