Saturday 26 September 2020

Comet 88P/Howell reaches perihelion.

Comet 88P/Howell reaches its perihelion (the closest point on its orbit to the Sun) at 8.24 pm GMT on Monday 28 September 2020, when it will be approximately 1.36 AU from the Sun (i.e. 136% of the distance between the Earth and the Sun, and some way inside the orbit of Mercury). At this time the comet will be 1.40 AU from the Earth, in the constellation of Scorpius, having a magnitude of 15.58, making it impossible to spot without a fairly good telescope, and not visible north of the Tropic of Cancer.

 
Image of Comet 88P/Howell taken from Valencia in Spain on 5 September 2020. José Chambó/Cometografía.

Comet 88P/Howell was discovered by American astronomer Ellen Howell on 29 August 1981; the name 88P/Howell implies that it was the 88th comet discovered, that it is a periodic comet, and that it was discovered by Ellen Howell.

 
The orbit and current position of Comet 88P/Howell. In The Sky.
 
Comet 88P/Howell has an orbital period of 2003 days (5.48 years) and a highly eccentric orbit tilted at an angle of 4.38° to the plain of the Solar System, that brings it from 1.40 AU from the Sun at perihelion (140% of the distance between the Earth and the Sun, and slightly inside the orbit of the planet Mars); to 4.86 AU from the Sun at aphelion (4386 times as far from the Sun as the Earth or slightly inside the orbit of the planet Jupiter). As a comet with a period of less than 20 years with an orbit angled at less than 30° to the plane of the Solar System, 88P/Howell is considered to be a Jupiter Family Comet.
 
Calculations have shown that 88P/Howell formerly orbited on a path further than the Sun, with a perihelion of 1.9 AU (i.e. it was 1.9 times as far from the Sun as the planet Earth its closest), until a close encounter with the planet Jupiter in 1978 shifted it onto its current course. The comet has regular close encounters with Jupiter, with the last having happened in June 2002, and the next predicted for May 2061. The Comet is also predicted to come close to the planet Mars in September 2031. It is predicted that another close encounter with Jupiter in October 2168 will cause it to shift its orbit again, so that moves onto a new orbital path that will bring it close to the Earth, with close encounters between 88P/Howell and the Earth predicted in July 2170, July 2181, and July 2192. 

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