210P/Christensen
Periodic comet
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210P/Christensen is a Jupiter family comet with an orbital period of 5.7 years. It was discovered by Eric J. Christensen on 26 May 2003 in images taken by the Catalina Sky Survey[1] and recovered in images obtained by STEREO, the first time a single-apparition comet was recovered by a spacecraft.[6]
Comet 210P/Christensen imaged from an 8-in reflector on 1 December 2025 | |
| Discovery[1] | |
|---|---|
| Discovered by | Eric J. Christensen |
| Discovery site | Catalina Sky Survey |
| Discovery date | 26 May 2003 |
| Designations | |
| P/2003 K2, P/2008 X4 | |
| Orbital characteristics[2][3] | |
| Epoch | 21 November 2025 (JD 2461000.5) |
| Observation arc | 22.35 years |
| Number of observations | 947 |
| Aphelion | 5.797 AU |
| Perihelion | 0.524 AU |
| Semi-major axis | 3.161 AU |
| Eccentricity | 0.83408 |
| Orbital period | 5.619 years |
| Inclination | 10.287° |
| 93.797° | |
| Argument of periapsis | 345.95° |
| Mean anomaly | 359.69° |
| Last perihelion | 22 November 2025 7 April 2020 |
| Next perihelion | 6 July 2031[4] |
| TJupiter | 2.492 |
| Earth MOID | 0.170 AU |
| Jupiter MOID | 0.019 AU |
| Physical characteristics[2] | |
| Dimensions | 0.87 km (0.54 mi)[5] |
| Comet total magnitude (M1) | 14.9 |
Observational history
Eric J. Christensen discovered the comet on 26 May 2003 in images taken with the 0.7-m Schmidt telescope of the Catalina Sky Survey. The comet had an estimated magnitude of 14.6 and a coma with an estimated diameter between 10 and 35 arcseconds and a faint tail.[1] Further observations revealed the comet had a short orbital period.[7]
In mid December 2008, Australian comet-hunter Alan Watson spotted in the STEREO/SECCHI Heliospheric Imager ("HI") HI-1B data a cometary object. Veteran German comet hunter Rainer Kracht recorded a few positions of the comet in the data and produced a set of very approximate orbital elements for it.[6] Maik Meyer noticed the similarity of these orbital elements to those of P/2003 K2 and the link was confirmed by Brian G. Marsden.[6][8] This was the first recovery of a single-apparition comet by a spacecraft.[6] The comet was observed from the ground on 14 December 2008, located low and in bright twilight, and on 31 December 2008 it had an estimated magnitude of 10.5.[9]
During the 2025 apparition, the comet passed 0.43 AU (64 million km; 40 million mi) from Earth on 8 November 2025 but was only 20 degrees from the Sun.[10] It came to perihelion on 22 November 2025. It was visible in SWAN in November 2025 around magnitude 11. On 26 November it was visible low in the morning twilight, with a faint tail about a quarter of a degree long and an estimated magnitude of 9.5.[11]
The comet has been locked in a 2:1 orbital resonance with Jupiter for the last 10,000 years and could be of asteroidal origin.[5] Its nucleus is estimated to be about 1.74 km (1.08 mi) in diameter.[5] It makes close approaches to Venus and on 17 September 1929 passed 0.032 AU (4.8 million km; 3.0 million mi) from Venus.[2]