Thursday, 30 December 2021

Comet C/2021 A1 (Leonard) approaches perihelion.

Comet C/2021 A1 (Leonard) will teach its perihelion (the closest point on its orbit to the Sun) slightly before 7.05 am GMT on Monday 3 January 2022, when it will be approximately 0.62 AU from the Sun (i.e. 0.62 times as far from the Sun as the planet Earth, or 92 033 000 km). At this time the comet will be 0.92 AU from the Earth, in the constellation of Piscis Austrinus (south of Aquarius and generally better observed from the Southern Hemisphere), having a magnitude of 5.1, making it easily visible with standard binoculars, although it will not be visible from much of the Northern Hemisphere.

The orbit and position at perihelion of C/2021 A1 (Leonard). The Sky Live.

C/2021 A1 (Leonard) was discovered on 3 January 2021 (exactly one year before its perihelion) by planetary scientist Gregory Leonard at the University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount Lemmon in the Catalina Mountains north of Tucson. The name  C/2021 A1 (Leonard) implies that it is a comet (C/), that it was the first comet like body (comet 1) discovered in the first half of January 2021 (period 2021) and that it was discovered by Leonard.

Conjunction of Comet C/2021 A1 (Leonard) and Messier 3, imaged on 3 December 2021 from South Florida (composite image made up from several exposures). Horizon Productions SFL/Flikr.

C/2021 A1 (Leonard) is a Parabolic Comet, which is to say a comet that was disrupted from an orbit in the Oort Cloud, and is passing through the Inner Solar System on a parabolic orbit that will probably not bring it back again. This parabolic trajectory tilted at an angle of 133° to the plain of the Solar System, that will bring it in to 0.62 AU from the Sun at perihelion on 3 January 2022, between the orbits of the planets Mercury and Venus.

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