177P/Barnard
Periodic comet
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Comet 177P/Barnard, also known as Barnard 2, is a periodic comet with an orbital period of 122 years. It fits the classical definition of a Halley-type comet with (20 years < period < 200 years).[4] It orbits near the ecliptic plane and has aphelion near the Kuiper cliff at 48 AU (7.2 billion km).
| Discovery | |
|---|---|
| Discovered by | Edward Emerson Barnard |
| Discovery date | June 24, 1889 |
| Designations | |
| 177P/1889 M1; 1889 III; 1889c; 177P/2006 M3 | |
| Orbital characteristics | |
| Epoch | 2013-Apr-18 (JD 2456400.5)[1] |
| Aphelion | 48.05 AU (47.74 AU in 2066)[2] |
| Perihelion | 1.12 AU |
| Semi-major axis | 24.58 AU |
| Eccentricity | 0.954 |
| Orbital period | 122 yr 120y 7m 16d (perihelion to perihelion) |
| Inclination | 31.05° |
| Last perihelion | August 28, 2006[3][4][1] June 21, 1889[1] |
| Next perihelion | April 13, 2127[5][1][6][3] |
The comet, also designated P/2006 M3, was discovered by Edward Emerson Barnard on June 24, 1889, and was re-discovered after 116 years.[7] On July 19, 2006, 177P came within 0.366 AU (54.8 million km) of Earth.[4][8] From late July through September 2006 it was slightly brighter than expected at 8th magnitude[3] in the constellations Hercules and then Draco. Perihelion was August 28, 2006. It was last observed in December 2006 when it was about 2 AU (300 million km) from the Sun.[4]
The only numbered comets with an orbital period longer than 177P/Barnard are: 153P/IkeyaâZhang (365 years), 273P/PonsâGambart (188 years), 35P/HerschelâRigollet (155 years), and 109P/Swift-Tuttle (133 years).
Of Barnard's other two periodic comets, the first, D/1884 O1 (Barnard 1) was last seen on November 20, 1884, and is thought to have disintegrated. The last, 206P/Barnard-Boattini marked the beginning of a new era in cometary astronomy, as it was the first to be discovered by photography. It was a lost comet after 1892, until accidentally rediscovered on October 7, 2008, by Andrea Boattini.