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

Comet 15P/Finlay reaches peak brightness

Dominic Ford, Editor
From the Comets feed

Objects: 15P/Finlay
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Comet 15P/Finlay is forecast to reach the brightest point in its 2021 apparition on 7 July. At that time, it will lie at a distance of 1.00 AU from the Sun, and at a distance of 1.14 AU from the Earth.

From Ashburn on 7 July it will be visible in the dawn sky, rising at 02:24 (EST) – 3 hours and 24 minutes before the Sun – and reaching an altitude of 22° above the eastern horizon before fading from view as dawn breaks at around 04:29.

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The events that comprise the 2021 apparition of 15P/Finlay are as follows:

Date Event
17 Jun 2021Comet 15P/Finlay passes perigee
07 Jul 2021Comet 15P/Finlay reaches peak brightness
13 Jul 2021Comet 15P/Finlay passes perihelion

The table below lists the times when 15P/Finlay will be visible from Ashburn day-by-day through its apparition:

Date Constellation Comet visibility
16 Jun 2021PiscesNot observable
18 Jun 2021PiscesNot observable
20 Jun 2021PiscesNot observable
22 Jun 2021CetusNot observable
24 Jun 2021CetusNot observable
26 Jun 2021AriesNot observable
28 Jun 2021AriesNot observable
30 Jun 2021AriesNot observable
02 Jul 2021AriesNot observable
04 Jul 2021AriesNot observable
06 Jul 2021AriesVisible from 04:26 until 04:28
Highest at 04:28, 22° above E horizon
08 Jul 2021AriesVisible from 04:24 until 04:30
Highest at 04:30, 23° above E horizon
10 Jul 2021TaurusVisible from 04:23 until 04:32
Highest at 04:32, 24° above E horizon
12 Jul 2021TaurusVisible from 04:22 until 04:33
Highest at 04:33, 24° above E horizon
14 Jul 2021TaurusVisible from 04:20 until 04:35
Highest at 04:35, 25° above E horizon
16 Jul 2021TaurusVisible from 04:19 until 04:37
Highest at 04:37, 25° above E horizon
18 Jul 2021TaurusVisible from 04:18 until 04:39
Highest at 04:39, 26° above E horizon
20 Jul 2021TaurusVisible from 04:17 until 04:41
Highest at 04:41, 27° above E horizon
22 Jul 2021TaurusVisible from 04:16 until 04:43
Highest at 04:43, 27° above E horizon
24 Jul 2021TaurusVisible from 04:15 until 04:46
Highest at 04:46, 28° above E horizon
26 Jul 2021TaurusVisible from 04:14 until 04:48
Highest at 04:48, 28° above E horizon

A more detailed table of 15P/Finlay's position on each night is available here. A diagram of the orbit of 15P/Finlay is available here.

Finder chart

The chart below shows the path of 15P/Finlay 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 15P/Finlay is currently available.

The comet's position on 7 July 2021 will be:

Object Right Ascension Declination Constellation Magnitude
Comet 15P/Finlay 03h14m10s 15°54'N Aries 8.4

The coordinates are given in J2000.0.

The sky on 7 Jul 2021

The sky on 7 July 2021
Twilight ends
Twilight begins

27-day old moon
Waning Crescent


27 days old

Rise Culm. Set
Mercury 04:27 11:42 18:57
Venus 08:00 15:07 22:14
Moon 03:39 11:15 18:57
Mars 08:19 15:20 22:22
Jupiter 22:59 04:23 09:46
Saturn 22:03 03:05 08:07
All times shown in EDT.


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 02 Jan 2024.

Image credit

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





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