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

C/2017 S3 (PANSTARRS) at perihelion

Dominic Ford, Editor
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Comet C/2017 S3 (PANSTARRS) will make its closest approach to the Sun, at a distance of 0.21 AU.

From Fairfield the 2018 apparition of C/2017 S3 (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.
06 Aug 2018 – C/2017 S3 (PANSTARRS) at perigee
16 Aug 2018 – C/2017 S3 (PANSTARRS) at perihelion
26 Jul 2018AurigaVisible from 03:49 until 04:26
Highest at 04:26, 27° above NE horizon
28 Jul 2018AurigaVisible from 04:10 until 04:29
Highest at 04:29, 24° above NE horizon
30 Jul 2018AurigaNot observable
01 Aug 2018AurigaNot observable
03 Aug 2018GeminiNot observable
05 Aug 2018GeminiNot observable
07 Aug 2018CancerNot observable
09 Aug 2018CancerNot observable
11 Aug 2018CancerNot observable
13 Aug 2018HydraNot observable
15 Aug 2018HydraNot observable
17 Aug 2018SextansNot observable
19 Aug 2018SextansNot observable
21 Aug 2018SextansNot observable
23 Aug 2018SextansNot observable
25 Aug 2018SextansNot observable
27 Aug 2018SextansNot observable
29 Aug 2018SextansNot observable
31 Aug 2018LeoNot observable
02 Sep 2018LeoNot observable
04 Sep 2018LeoNot observable

A more detailed table of C/2017 S3 (PANSTARRS)'s position on each night is available here. A diagram of the orbit of C/2017 S3 (PANSTARRS) is available here.

At the moment of perihelion it will not be readily observable since it will be very close to the Sun, at a separation of only 11° from it.

Finder chart

The chart below shows the path of C/2017 S3 (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.

No estimate for the brightness of comet C/2017 S3 (PANSTARRS) is currently available.

The comet's position at perihelion will be:

Object Right Ascension Declination Constellation Magnitude
Comet C/2017 S3 (PANSTARRS) 09h32m00s +02°03' Hydra 4.4

The coordinates are given in J2000.0.

The sky on 16 August 2018
Twilight ends
Twilight begins

5-day old moon
Waxing Crescent


5 days old

Rise Culm. Set
Mercury 05:13 12:06 19:00
Venus 10:01 15:46 21:31
Moon 12:05 17:37 23:10
Mars 19:02 23:23 03:47
Jupiter 12:57 18:04 23:12
Saturn 16:46 21:24 02:06
All times shown in EDT.


Never attempt to point a pair of binoculars or a telescope at an object close to the Sun. Doing so may result in immediate and permanent blindness.


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 06 Dec 2020.

Image credit

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






Color scheme