210P/Christensen is a Jupiter family periodic 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.[5]
 The recovery image of the comet by STEREO, on 13 December 2008 | |
| Discovery[1] | |
|---|---|
| Discovered by | Eric J. Christensen |
| Discovery date | 26 May 2003 |
| Designations | |
| P/2003 K2, P/2008 X4 | |
| Orbital characteristics[3] | |
| Epoch | 3 February 2010 |
| Aphelion | 5.817 AU |
| Perihelion | 0.534 AU |
| Semi-major axis | 3.176 AU |
| Eccentricity | 0.8317 |
| Orbital period | 5.659 years |
| Inclination | 10.217° |
| 93.872° | |
| Argument of periapsis | 345.766° |
| Last perihelion | 7 April 2020 |
| Next perihelion | 22 November 2025 [2] |
| TJupiter | 2.492 |
| Earth MOID | 0.170 AU |
| Jupiter MOID | 0.018 AU |
| Physical characteristics | |
| Dimensions | ≤ 1.74 km[4] |
| Comet total magnitude (M1) | 14.9[3] |
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.[6]
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.[5] Maik Meyer noticed the similarity of these orbital elements to those of P/2003 K2 and the link was confirmed by Brian Marsden.[5][7] This was the first recovery by a spacecraft of a single-apparition comet (a comet that had only been observed to pass the Sun once) by a spacecraft.[5] The comet was observed from the ground on 31 November 2008, with an estimated magnitude of 11.[8]
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.[4]