astro.wikisort.org - Comet

78P/Gehrels, also known as Gehrels 2, is a Jupiter-family periodic comet in the Solar System with a current orbital period of 7.22 years.

78P/Gehrels

Discovery
Discovered by	Tom Gehrels
Discovery date	September 29, 1973
Alternative designations	1973 XI; 1981 XVII; 1989 XVII
Orbital characteristics A
Epoch	March 6, 2006
Aphelion	5.462 AU
Perihelion	2.009 AU
Semi-major axis	3.735 AU
Eccentricity	0.4622
Orbital period	7.22 yr
Inclination	6.2530°
Last perihelion	April 2, 2019[1][2] January 12, 2012[3] October 27, 2004[1][4]
Next perihelion	2026-06-25[5]

It was discovered by Tom Gehrels at the Lunar and Planetary Laboratory, Arizona, USA on photographic plates exposed between 29 September and 5 October 1973 at the Palomar Observatory. It had a brightness of apparent magnitude of 15. Brian G. Marsden computed the parabolic and elliptical orbits which suggested an orbital period of 8.76 years, later revising the data to give a perihelion date of 30 November 1963 and orbital period of 7.93 years.[6]

The comet's predicted next appearance in 1981 was observed by W. and A. Cochran at the McDonald Observatory, Texas on 8 June 1981. It was observed again in 1989 and in 1997, when favourable conditions meant that brightness increased to magnitude 12.[6] It has subsequently been observed in 2004 when it reached magnitude 10, 2012, and 2018.[1]

Outward migration

Comet 78P/Gehrels' aphelion (furthest distance from the Sun) of 5.4AU[3] is in the zone of control of the giant planet Jupiter and the orbit of the comet is frequently perturbed by Jupiter.[7] On September 15, 2029, the comet will pass within 0.018 AU (2.7 million kilometers) of Jupiter[7] and be strongly perturbed. By the year 2200, the comet will have a centaur-like orbit with a perihelion (closest distance to the Sun) near Jupiter.[8] This outward migration from a perihelion of 2AU to a perihelion of ~5AU could cause the comet to go dormant.

See also

• List of numbered comets

References

External links

• Orbital simulation from JPL (Java) / Horizons Ephemeris
• 78P/Gehrels – Minor Planet Center
• 78P/Gehrels 2 (2012)
• 78P at Kronk's Cometography
• Lightcurve (Artyom Novichonok)
• 78P as seen by 10" GRAS-04 on 2011-05-03 (120 sec x 6)
• 78P as seen by 0.3-metre (12 in) Schmidt-Cassegrain on 2011 08 06 (3 x 748 sec) and 2011 08 09 (6 x 600 sec)

Numbered comets
Previous 77P/Longmore	78P/Gehrels	Next 79P/du Toit–Hartley

На других языках

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- [en] 78P/Gehrels

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[ru] 78P/Герельса

Комета Герельса 2 (78P/Gehrels) — короткопериодическая комета из семейства Юпитера, которая была открыта 29 сентября 1973 года американским астрономом Томом Герельсом в Паломарской обсерватории. Обладает довольно коротким периодом обращения вокруг Солнца — всего чуть более 7,21 лет.

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