78P/Gehrels

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 byTom Gehrels
Discovery dateSeptember 29, 1973
Alternative
designations		1973 XI; 1981 XVII; 1989 XVII
Orbital characteristics A
EpochMarch 6, 2006
Aphelion5.462 AU
Perihelion2.009 AU
Semi-major axis3.735 AU
Eccentricity0.4622
Orbital period7.22 yr
Inclination6.2530°
Last perihelionApril 2, 2019[1][2]
January 12, 2012[3]
October 27, 2004[1][4]
Next perihelion2026-06-25[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.

The Outward Migration of 78P/Gehrels
Year (epoch)2009[3]20302200[8]
Semi-major axis3.736.029.37
Perihelion2.004.084.99
Aphelion5.467.9613.7
Comet 78P passing within 0.018 AU of Jupiter in 2029.[7]
gollark: ++remind 1y Hi epicbot
gollark: ++remind 1mo ApioBees™
gollark: +>markov
gollark: 623361064250639049750086562710953591946589751413103482276930624743536325691607815478181152843667957061108615331504452127473924544945423682886061340841486377670096120715124914043027253860764823634143346235189757664521641376796903149501910857598442391986291642193994907236234646844117394032659184044378051333894525742399508296591228508555821572503107125701266830240292952522011872676756220415420516184163484756516999811614101002996078386909291603028840026910414079288621507842451670908700069928212066041837180653556725253256753286129104248776182582976515795984703562226293486003415872298053498965022629174878820273420922224533985626476691490556284250391275771028402799806636582548892648802545661017296702664076559042909945681506526530537182941270336931378517860904070866711496558343434769338578171138645587367812301458768712660348913909562009939361031029161615288138437909904231747336394804575931493140529763475748119356709110137751721008031559024853090669203767192203322909433467685142214477379393751703443661991040337511173547191855046449
gollark: 36534940603402166544375589004563288225054525564056448246515187547119621844396582533754388569094113031509526179378002974120766514793942590298969594699556576121865619673378623625612521632086286922210327488921865436480229678070576561514463204692790682120738837781423356282360896320806822246801224826117718589638140918390367367222088832151375560037279839400415297002878307667094447456013455641725437090697939612257142989467154357846878861444581231459357198492252847160504922124247014121478057345510500801908699603302763478708108175450119307141223390866393833952942578690507643100638351983438934159613185434754649556978103829309716465143840700707360411237359984345225161050702705623526601276484830840761183013052793205427462865403603674532865105706587488225698157936789766974220575059683440869735020141020672358502007245225632651341055924019027421624843914035998953539459094407046912091409387001264560016237428802109276457931065792295524988727584610126483699989225695968815920560010165525637567856672279661988578279484885583439751874

See also

References
  1. Seiichi Yoshida (2006-10-03). "78P/Gehrels 2". Seiichi Yoshida's Comet Catalog. Retrieved 2010-02-24.
  2. Syuichi Nakano (2011-06-10). "78P/Gehrels 2 (NK 2102)". OAA Computing and Minor Planet Sections. Retrieved 2012-02-18.
  3. "JPL Small-Body Database Browser: 78P/Gehrels 2" (2011-05-21 last obs). Retrieved 2009-05-11.
  4. Syuichi Nakano (2009-04-20). "78P/Gehrels 2 (NK 1760)". OAA Computing and Minor Planet Sections. Retrieved 2010-02-24.
  5. "78P/Gehrels Orbit". Minor Planet Center. Retrieved 2020-06-29.
  6. Kronk, Gary W. "78P/Gehrels 2". Cometography. Retrieved 25 February 2015.
  7. "JPL Close-Approach Data: 78P/Gehrels 2" (2006-02-26 last obs). Retrieved 2009-05-11.
  8. Heider. "Orbital Elements of 78P/Gehrels in 2200". Archived from the original on 2015-06-06. Retrieved 2009-05-11.
Numbered comets
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