 Comet Crommelin photographed byFerdinand Quénisset on 28 October 1928 | |
| Discovery | |
|---|---|
| Discovered by |
|
| Discovery date | 23 February 1818 |
| Designations | |
| |
| |
| Orbital characteristics[2][3] | |
| Epoch | 18 July 2011 (JD 2455760.5) |
| Observation arc | 193.92 years |
| Number of observations | 497 |
| Aphelion | 17.659 AU |
| Perihelion | 0.748 AU |
| Semi-major axis | 9.204 AU |
| Eccentricity | 0.91874 |
| Orbital period | 27.922 years |
| Inclination | 28.96° |
| 250.64° | |
| Argument of periapsis | 195.98° |
| Mean anomaly | 359.41° |
| Last perihelion | 3 August 2011 |
| Next perihelion | 27 May 2039[1] |
| TJupiter | 1.481 |
| EarthMOID | 0.229 AU |
| JupiterMOID | 1.009 AU |
| Physical characteristics[2] | |
Mean diameter | <12±3 km[4][a] |
| Comet total magnitude (M1) | 12.7 |
| Comet nuclear magnitude (M2) | 16.3 |
Comet Crommelin, also known asComet Pons-Coggia-Winnecke-Forbes, is aperiodic comet with anorbital period of almost 28 years. It fits the classical definition of a Halley-type comet with (20 years <period < 200 years). It is named after the British astronomerAndrew C. D. Crommelin who calculated its orbit in 1930. It is one of only five known comets that are not named after their discoverer(s)[b] It next comes toperihelion (closest approach to the Sun) around 27 May 2039 when it will be near a maximum near-perihelion distance from Earth.
The first observation was byJean-Louis Pons (Marseille,France) on February 23, 1818, he followed the comet until February 27 but was prevented further by bad weather.Johann Franz Encke attempted to calculate the orbit but was left with very large errors.
In 1872,John R. Hind produced a rough orbital calculation and observed it was close to that ofComet Biela, based on these observations,Edmund Weiss later speculated it may have been part of Biela's comet.
The next observation was on November 10, 1873, byJérôme E. Coggia (Marseille,France), and again on November 11 byFriedrich A. T. Winnecke (Strasbourg,France), but it was lost by November 16. Weiss and Hind took up the calculations and tried to match it again with the 1818 appearance.
A third discovery was byAlexander F. I. Forbes (Cape Town,South Africa) on 19 November 1928, and confirmed byHarry E. Wood (Union Observatory,South Africa) on November 21. It was Crommelin who eventually established the orbit and finally linked the 1818 (Pons) and 1873 (Coggia-Winnecke) comets to it(also seeLost comet).
On its latest return, 27P/Crommelin was recovered on May 12, 2011, atapparent magnitude 18.7[5] and peaked at magnitude 10.7 at perihelion on August 3.[6] 27P/Crommelin was last observed in January 2012, and passed about 1.5 AU (220 million km) from Saturn on 11 July 2015.[2]
The nextperihelion will be on 27 May 2039.[3][1] Near perihelion the comet will be 0.74 AU from the Sun and 1.73 AU from Earth.[1] This is about as far from Earth as the comet can get during perihelion.
On 22 December 2120, it will pass 0.297 AU (44.4 million km) from Earth.[2]
| Numbered comets | ||
|---|---|---|
| Previous 26P/Grigg–Skjellerup | 27P/Crommelin | Next 28P/Neujmin |
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