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

C/2021 A2 (NEOWISE) at perihelion

Dominic Ford, Editor
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Comet C/2021 A2 (NEOWISE) will make its closest approach to the Sun, at a distance of 1.40 AU.

From Ashburn the 2020–2021 apparition of C/2021 A2 (NEOWISE) 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.
22 Jan 2021 – C/2021 A2 (NEOWISE) at perihelion
01 Jan 2021CentaurusNot observable
03 Jan 2021VelaNot observable
05 Jan 2021VelaNot observable
07 Jan 2021VelaNot observable
09 Jan 2021VelaNot observable
11 Jan 2021VelaNot observable
13 Jan 2021VelaNot observable
15 Jan 2021VelaNot observable
17 Jan 2021VelaNot observable
19 Jan 2021VelaNot observable
21 Jan 2021VelaNot observable
23 Jan 2021PyxisNot observable
25 Jan 2021PyxisNot observable
27 Jan 2021PuppisVisible from 23:32 until 00:34
Highest at 00:03, 22° above S horizon
29 Jan 2021PuppisVisible from 21:41 until 01:27
Highest at 23:34, 27° above S horizon
31 Jan 2021PuppisVisible from 20:32 until 01:46
Highest at 23:09, 33° above S horizon
02 Feb 2021PuppisVisible from 19:34 until 01:56
Highest at 22:45, 39° above S horizon
04 Feb 2021MonocerosVisible from 18:43 until 02:00
Highest at 22:21, 44° above S horizon
06 Feb 2021MonocerosVisible from 18:41 until 02:01
Highest at 21:59, 50° above S horizon
08 Feb 2021MonocerosVisible from 18:43 until 01:59
Highest at 21:37, 56° above S horizon
10 Feb 2021MonocerosVisible from 18:45 until 01:55
Highest at 21:17, 61° above S horizon

A more detailed table of C/2021 A2 (NEOWISE)'s position on each night is available here. A diagram of the orbit of C/2021 A2 (NEOWISE) 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 11° above the horizon.

Finder chart

The chart below shows the path of C/2021 A2 (NEOWISE) 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 11 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.

You will probably require a telescope to see this comet. It is unlikely to be visible through bird-watching binoculars, and even less likely to be visible to the unaided eye.

The comet's position at perihelion will be:

Object Right Ascension Declination Constellation Magnitude
Comet C/2021 A2 (NEOWISE) 09h07m20s 38°57'S Vela 11.1

The coordinates are given in J2000.0.

The sky on 22 January 2021
Twilight ends
Twilight begins

9-day old moon
Waxing Gibbous


9 days old

Rise Culm. Set
Mercury 08:21 13:34 18:48
Venus 06:31 11:16 16:00
Moon 12:28 19:36 02:53
Mars 11:24 18:18 01:12
Jupiter 07:42 12:41 17:40
Saturn 07:30 12:26 17:21
All times shown in EST.


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 25 Jan 2022.

Image credit

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






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