© Andy Roberts 1997. Pictured comet is C/1995 O1 Hale-Bopp.

C/2021 A1 (Leonard) at perihelion

Dominic Ford, Editor
From the Comets feed

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Comet C/2021 A1 (Leonard) will make its closest approach to the Sun, at a distance of 0.62 AU.

From Seattle the 2021–2022 apparition of C/2021 A1 (Leonard) will progress as follows:

Begin typing the name of a town near to you, and then select the town from the list of options which appear below.
12 Dec 2021 – C/2021 A1 (Leonard) at perigee
02 Jan 2022 – C/2021 A1 (Leonard) at perihelion
12 Dec 2021OphiuchusNot observable
14 Dec 2021ScutumNot observable
16 Dec 2021SagittariusNot observable
18 Dec 2021SagittariusNot observable
20 Dec 2021MicroscopiumNot observable
22 Dec 2021MicroscopiumNot observable
24 Dec 2021MicroscopiumNot observable
26 Dec 2021MicroscopiumNot observable
28 Dec 2021MicroscopiumNot observable
30 Dec 2021Piscis AustrinusNot observable
01 Jan 2022Piscis AustrinusNot observable
03 Jan 2022Piscis AustrinusNot observable
05 Jan 2022Piscis AustrinusNot observable
07 Jan 2022Piscis AustrinusNot observable
09 Jan 2022Piscis AustrinusNot observable
11 Jan 2022Piscis AustrinusNot observable
13 Jan 2022Piscis AustrinusNot observable
15 Jan 2022Piscis AustrinusNot observable
17 Jan 2022Piscis AustrinusNot observable
19 Jan 2022Piscis AustrinusNot observable
21 Jan 2022Piscis AustrinusNot observable

A more detailed table of C/2021 A1 (Leonard)'s position on each night is available here. A diagram of the orbit of C/2021 A1 (Leonard) is available here.

At the moment of perihelion it will not be readily observable since it will lie so far south that it will never rise more than 6° above the horizon.

Finder chart

The chart below shows the path of C/2021 A1 (Leonard) over the course of its apparition, as calculated from the orbital elements published by the Minor Planet Center (MPC). It is available for download, either on dark background, in PNG, PDF or SVG formats, or on a light background, in PNG, PDF or SVG formats. It was produced using StarCharter.

Comet brightnesses

Comets are intrinsically highly unpredictable objects, since their brightness depends on the scattering of sunlight from dust particles in the comet's coma and tail. This dust is continually streaming away from the comet's nucleus, and its density at any particular time is governed by the rate of sublimation of the ice in the comet's nucleus, as it is heated by the Sun's rays. It also depends on the amount of dust that is mixed in with that ice. This is very difficult to predict in advance, and can be highly variable even between successive apparitions of the same comet.

In consequence, while the future positions of comets are usually known with a high degree of confidence, their future brightnesses are not. For most comets, we do not publish any magnitude estimates at all. For the few comets where we do make estimates, we generally prefer the BAA's magnitude parameters to those published by the Minor Planet Center, since they are typically updated more often.

Based on the magnitude parameters published for this comet by the BAA Comet Section, we estimate that it may be around mag 5 at perihelion. This estimate is based on observations that the BAA has received from amateur astronomers, assuming that its current level of activity will remain constant.

The comet's position at perihelion will be:

Object Right Ascension Declination Constellation Magnitude
Comet C/2021 A1 (Leonard) 21h37m40s 35°28'S 5.4

The coordinates are given in J2000.0.

The sky on 02 January 2022
Twilight ends
Twilight begins

29-day old moon
Waxing Crescent


29 days old

Rise Culm. Set
Mercury 09:10 13:31 17:52
Venus 08:13 12:52 17:31
Moon 08:18 12:17 16:18
Mars 05:55 10:10 14:26
Jupiter 10:22 15:31 20:39
Saturn 09:37 14:17 18:57
All times shown in PST.


This event was automatically generated on the basis of orbital elements published by the Minor Planet Center (MPC) , and is updated whenever new elements become available. It was last updated on 04 Jan 2022.

Image credit

© Andy Roberts 1997. Pictured comet is C/1995 O1 Hale-Bopp.






Color scheme