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

46P/Wirtanen reaches its brightest

Dominic Ford, Editor
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Comet 46P/Wirtanen is forecast to reach its brightest. It will lie at a distance of 1.05 AU from the Sun, and at a distance of 0.07 AU from the Earth.

From Ashburn the 2018–2019 apparition of 46P/Wirtanen 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.
12 Dec 2018 – 46P/Wirtanen at perihelion
15 Dec 2018 – 46P/Wirtanen reaches its brightest
15 Dec 2018 – 46P/Wirtanen at perigee
24 Nov 2018FornaxVisible from 20:17 until 00:59
Highest at 22:38, 24° above S horizon
26 Nov 2018FornaxVisible from 19:54 until 01:12
Highest at 22:33, 25° above S horizon
28 Nov 2018EridanusVisible from 19:37 until 01:32
Highest at 22:34, 28° above S horizon
30 Nov 2018EridanusVisible from 19:16 until 01:51
Highest at 22:33, 30° above S horizon
02 Dec 2018EridanusVisible from 18:57 until 02:13
Highest at 22:35, 34° above S horizon
04 Dec 2018EridanusVisible from 18:36 until 02:35
Highest at 22:35, 38° above S horizon
06 Dec 2018EridanusVisible from 18:17 until 03:01
Highest at 22:39, 43° above S horizon
08 Dec 2018EridanusVisible from 18:00 until 03:34
Highest at 22:47, 49° above S horizon
10 Dec 2018TaurusVisible from 17:43 until 04:07
Highest at 22:55, 56° above S horizon
12 Dec 2018TaurusVisible from 17:31 until 04:43
Highest at 23:05, 64° above S horizon
14 Dec 2018TaurusVisible from 17:33 until 05:25
Highest at 23:20, 72° above S horizon
16 Dec 2018AurigaVisible from 17:31 until 06:09
Highest at 23:36, 80° above S horizon
18 Dec 2018AurigaVisible from 17:36 until 06:40
Highest at 23:52, 88° above S horizon
20 Dec 2018AurigaVisible from 17:38 until 06:38
Highest at 00:16, 86° above N horizon
22 Dec 2018AurigaVisible from 17:40 until 06:36
Highest at 00:38, 82° above N horizon
24 Dec 2018LynxVisible from 17:46 until 06:34
Highest at 00:58, 78° above N horizon
26 Dec 2018LynxVisible from 17:47 until 06:31
Highest at 01:15, 75° above N horizon
28 Dec 2018LynxVisible from 17:53 until 06:33
Highest at 01:32, 74° above N horizon
30 Dec 2018LynxVisible from 17:55 until 06:31
Highest at 01:47, 72° above N horizon
01 Jan 2019LynxVisible from 18:01 until 06:29
Highest at 01:56, 72° above N horizon
03 Jan 2019Ursa MajorVisible from 18:06 until 06:26
Highest at 02:04, 71° above N horizon

A more detailed table of 46P/Wirtanen's position on each night is available here. A diagram of the orbit of 46P/Wirtanen is available here.

On 15 December it will be visible in the evening sky, becoming accessible around 17:54 (EST), 23° above your eastern horizon, as dusk fades to darkness. It will then reach its highest point in the sky at 23:03, 72° above your southern horizon. It will continue to be observable until around 04:49, when it sinks below 16° above your western horizon.

Finder chart

The chart below shows the path of 46P/Wirtanen 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 46P/Wirtanen is currently available.

The comet's position on 15 December 2018 will be:

Object Right Ascension Declination Constellation Magnitude
Comet 46P/Wirtanen 04h31m30s 21°54'N Taurus 3.1

The coordinates are given in J2000.0.

The sky on 15 December 2018
Twilight ends
Twilight begins

8-day old moon
Waxing Gibbous


8 days old

Rise Culm. Set
Mercury 05:36 10:36 15:37
Venus 03:40 09:05 14:29
Moon 12:45 18:37 00:38
Mars 12:05 17:51 23:38
Jupiter 06:07 10:58 15:49
Saturn 08:31 13:15 18:00
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 Jul 2021.

Image credit

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






Color scheme