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

8P/Tuttle reaches its brightest

Dominic Ford, Editor
From the Comets feed

Objects: 8P/Tuttle
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Comet 8P/Tuttle is forecast to reach its brightest. It will lie at a distance of 1.02 AU from the Sun, and at a distance of 1.82 AU from the Earth.

From Ashburn the 2021 apparition of 8P/Tuttle will progress as follows:

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27 Aug 2021 – 8P/Tuttle at perihelion
31 Aug 2021 – 8P/Tuttle reaches its brightest
10 Aug 2021GeminiNot observable
12 Aug 2021GeminiNot observable
14 Aug 2021CancerNot observable
16 Aug 2021CancerNot observable
18 Aug 2021CancerNot observable
20 Aug 2021CancerNot observable
22 Aug 2021CancerNot observable
24 Aug 2021CancerNot observable
26 Aug 2021HydraNot observable
28 Aug 2021HydraNot observable
30 Aug 2021HydraNot observable
01 Sep 2021HydraNot observable
03 Sep 2021HydraNot observable
05 Sep 2021HydraNot observable
07 Sep 2021HydraNot observable
09 Sep 2021HydraNot observable
11 Sep 2021HydraNot observable
13 Sep 2021HydraNot observable
15 Sep 2021SextansNot observable
17 Sep 2021HydraNot observable
19 Sep 2021HydraNot observable

A more detailed table of 8P/Tuttle's position on each night is available here. A diagram of the orbit of 8P/Tuttle is available here.

On 31 August it will not be observable – it will reach its highest point in the sky during daytime and will be no higher than 2° above the horizon at dawn.

Finder chart

The chart below shows the path of 8P/Tuttle 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 31 August 2021. 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 31 August 2021 will be:

Object Right Ascension Declination Constellation Magnitude
Comet 8P/Tuttle 08h54m10s 2°32'N Hydra 8.9

The coordinates are given in J2000.0.

The sky on 31 August 2021
Twilight ends
Twilight begins

23-day old moon
Waning Crescent


23 days old

Rise Culm. Set
Mercury 08:35 14:34 20:33
Venus 09:55 15:34 21:14
Moon 00:10 07:50 15:35
Mars 07:37 13:55 20:13
Jupiter 19:08 00:24 05:39
Saturn 18:11 23:09 04:07
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 04 Jan 2022.

Image credit

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






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