| 10P/Tempel | |
| Discoverer: | Ernst Wilhelm Leberecht Tempel |
| Discovery Date: | July 4, 1873 |
| Designations: | 1873 II; 1878 III; 1894 III; 1899 IV; 1904 III; 1915 I; 1920 II; 1925 IV; 1930 VII; 1946 III; 1951 VIII; 1957 II; 1962 VI; 1967 X; 1972 X; 1978 V; 1983 X; 1988 XIV; 1994 VII; |
| Epoch: | 2026-07-19 (JD 2461240.5) |
| Semimajor: | 3.065 AU |
| Perihelion: | 1.418 AU |
| Aphelion: | 4.71 AU |
| Eccentricity: | 0.5374 |
| Period: | 5.37 yr |
| Inclination: | 12.03° |
| Asc Node: | 117.8° |
| Arg Peri: | 195.5° |
| Earth Moid: | 0.41AU |
| Last P: | 24 March 2021 14 November 2015 4 July 2010 |
| Next P: | 2026-Aug-02 |
| Dimensions: | 10.6 km |
10P/Tempel, also known as Tempel 2, is a periodic Jupiter-family comet with a 5-year orbital period. It was discovered on July 4, 1873 by Wilhelm Tempel. At the perihelion passage on 2 August 2026 the solar elongation is calculated at 164 degrees, with apparent magnitude approximately 8, with closest approach to Earth on 3 August 2026 at a distance of 0.414abbr=unitNaNabbr=unit.
| 2026-Aug-03 20:59 ± 1 min | 0.414abbr=unitNaNabbr=unit | 1.42AU | 6.5 | 31.0 | ± 204 km | Horizons |
The comet nucleus is estimated to be roughly the size of Halley's Comet at 10.6 kilometers in diameter with a low albedo of 0.022. The nucleus is dark because hydrocarbons on the surface have been converted to a dark, tar like substance by solar ultraviolet radiation. The nucleus is large enough that even near aphelion (furthest distance from the Sun which is near the orbit of Jupiter) the comet remains brighter than about magnitude 21.During the 2010 apparition the comet brightened to about apparent magnitude 8. The most favorable apparition of 10P/Tempel 2 was in 1925 when it came within 0.35abbr=unitNaNabbr=unit of Earth with an apparent magnitude of 6.5.
The Jet Propulsion Laboratory proposed a flyby of the comet with a flight spare of Mariner 4. The probe was instead used for a Venus flyby as Mariner 5.[1]