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

C/2017 K2 (PANSTARRS) reaches its brightest

Dominic Ford, Editor
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Comet C/2017 K2 (PANSTARRS) is forecast to reach its brightest. It will lie at a distance of 1.82 AU from the Sun, and at a distance of 2.35 AU from the Earth.

From Fairfield the 2022–2023 apparition of C/2017 K2 (PANSTARRS) 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.
19 Dec 2022 – C/2017 K2 (PANSTARRS) at perihelion
11 Jan 2023 – C/2017 K2 (PANSTARRS) reaches its brightest
21 Dec 2022PavoNot observable
23 Dec 2022PavoNot observable
25 Dec 2022PavoNot observable
27 Dec 2022PavoNot observable
29 Dec 2022PavoNot observable
31 Dec 2022PavoNot observable
02 Jan 2023PavoNot observable
04 Jan 2023PavoNot observable
06 Jan 2023PavoNot observable
08 Jan 2023PavoNot observable
10 Jan 2023PavoNot observable
12 Jan 2023PavoNot observable
14 Jan 2023PavoNot observable
16 Jan 2023PavoNot observable
18 Jan 2023PavoNot observable
20 Jan 2023PavoNot observable
22 Jan 2023PavoNot observable
24 Jan 2023IndusNot observable
26 Jan 2023IndusNot observable
28 Jan 2023IndusNot observable
30 Jan 2023IndusNot observable

A more detailed table of C/2017 K2 (PANSTARRS)'s position on each night is available here. A diagram of the orbit of C/2017 K2 (PANSTARRS) is available here.

On 11 January it will not be observable because it will lie so far south that it never rises above the horizon.

Finder chart

The chart below shows the path of C/2017 K2 (PANSTARRS) 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 6 on 11 January 2023. This estimate is based on observations that the BAA has received from amateur astronomers, assuming that its current level of activity will remain constant.

This comet is not expected to be visible to the naked eye, but might be visible through bird-watching binoculars.

The comet's position on 11 January 2023 will be:

Object Right Ascension Declination Constellation Magnitude
Comet C/2017 K2 (PANSTARRS) 19h53m50s 68°23'S Pavo 6.3

The coordinates are given in J2000.0.

The sky on 11 January 2023
Twilight ends
Twilight begins

19-day old moon
Waning Gibbous


19 days old

Rise Culm. Set
Mercury 06:27 11:17 16:08
Venus 08:29 13:22 18:15
Moon 20:13 03:16 10:08
Mars 13:12 20:49 04:27
Jupiter 10:36 16:38 22:41
Saturn 09:03 14:12 19:22
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 27 Dec 2021.

Image credit

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






Color scheme