© 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 2.48 AU from the Sun, and at a distance of 1.89 AU from the Earth.

From Seattle the 2022 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.
04 Aug 2022 – C/2017 K2 (PANSTARRS) reaches its brightest
14 Jul 2022OphiuchusVisible from 22:44 until 01:59
Highest at 22:44, 39° above S horizon
16 Jul 2022OphiuchusVisible from 22:42 until 01:42
Highest at 22:42, 38° above S horizon
18 Jul 2022OphiuchusVisible from 22:39 until 01:26
Highest at 22:39, 37° above S horizon
20 Jul 2022OphiuchusVisible from 22:36 until 01:09
Highest at 22:36, 36° above S horizon
22 Jul 2022OphiuchusVisible from 22:32 until 00:52
Highest at 22:32, 35° above S horizon
24 Jul 2022OphiuchusVisible from 22:29 until 00:35
Highest at 22:29, 33° above S horizon
26 Jul 2022OphiuchusVisible from 22:25 until 00:18
Highest at 22:25, 32° above S horizon
28 Jul 2022OphiuchusVisible from 22:22 until 00:00
Highest at 22:22, 31° above S horizon
30 Jul 2022OphiuchusVisible from 22:18 until 23:43
Highest at 22:18, 30° above S horizon
01 Aug 2022OphiuchusVisible from 22:14 until 23:26
Highest at 22:14, 28° above SW horizon
03 Aug 2022ScorpiusVisible from 22:10 until 23:08
Highest at 22:10, 27° above SW horizon
05 Aug 2022ScorpiusVisible from 22:06 until 22:50
Highest at 22:06, 26° above SW horizon
07 Aug 2022ScorpiusVisible from 22:02 until 22:32
Highest at 22:02, 25° above SW horizon
09 Aug 2022ScorpiusVisible from 21:58 until 22:14
Highest at 21:58, 23° above SW horizon
11 Aug 2022ScorpiusVisible from 21:53 until 21:55
Highest at 21:53, 22° above SW horizon
13 Aug 2022ScorpiusNot observable
15 Aug 2022ScorpiusNot observable
17 Aug 2022ScorpiusNot observable
19 Aug 2022ScorpiusNot observable
21 Aug 2022ScorpiusNot observable
23 Aug 2022ScorpiusNot 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 4 August it will become visible around 22:08 (PDT), 26° above your south-western horizon, as dusk fades to darkness. It will then sink towards the horizon, setting at 01:45.

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 9 on 4 August 2022. 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 4 August 2022 will be:

Object Right Ascension Declination Constellation Magnitude
Comet C/2017 K2 (PANSTARRS) 16h22m00s 12°13'S Scorpius 8.6

The coordinates are given in J2000.0.

The sky on 04 August 2022
Twilight ends
Twilight begins

7-day old moon
Waxing Crescent


7 days old

Rise Culm. Set
Mercury 07:28 14:27 21:26
Venus 03:59 11:47 19:36
Moon 13:18 18:36 23:41
Mars 00:11 07:29 14:47
Jupiter 22:38 04:50 11:02
Saturn 21:04 01:58 06:52
All times shown in PDT.


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 01 Aug 2022.

Image credit

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






Color scheme