Comet 161P/Hartley-IRAS passes perihelion

Dominic Ford, Editor
From the Comets feed


Comet 161P/Hartley-IRAS will make its closest approach to the Sun on 28 November, at a distance of 1.27 AU.

From Cambridge on the day of perihelion it will become visible at around 17:25 (EST), 46° above your western horizon, as dusk fades to darkness. It will then sink towards the horizon, setting at 21:50.

The events that comprise the 2026 apparition of 161P/Hartley-IRAS are as follows:

Date Event
28 Nov 2026Comet 161P/Hartley-IRAS passes perihelion

The table below lists the times when 161P/Hartley-IRAS will be visible from Cambridge day-by-day through its apparition:

Date Constellation Comet visibility
07 Nov 2026AquilaVisible from 17:38 until 21:13
Highest at 17:38, 58° above SW horizon
09 Nov 2026AquilaVisible from 17:36 until 21:03
Highest at 17:36, 57° above SW horizon
11 Nov 2026AquilaVisible from 17:35 until 20:54
Highest at 17:35, 56° above SW horizon
13 Nov 2026SagittaVisible from 17:33 until 20:45
Highest at 17:33, 55° above SW horizon
15 Nov 2026SagittaVisible from 17:31 until 20:36
Highest at 17:31, 54° above SW horizon
17 Nov 2026SagittaVisible from 17:30 until 20:27
Highest at 17:30, 53° above SW horizon
19 Nov 2026SagittaVisible from 17:29 until 20:18
Highest at 17:29, 52° above SW horizon
21 Nov 2026SagittaVisible from 17:28 until 20:10
Highest at 17:28, 51° above SW horizon
23 Nov 2026SagittaVisible from 17:26 until 20:02
Highest at 17:26, 50° above SW horizon
25 Nov 2026SagittaVisible from 17:26 until 19:54
Highest at 17:26, 49° above SW horizon
27 Nov 2026SagittaVisible from 17:25 until 19:46
Highest at 17:25, 48° above W horizon
29 Nov 2026SagittaVisible from 17:24 until 19:38
Highest at 17:24, 46° above W horizon
01 Dec 2026SagittaVisible from 17:24 until 19:30
Highest at 17:24, 45° above W horizon
03 Dec 2026SagittaVisible from 17:23 until 19:22
Highest at 17:23, 44° above W horizon
05 Dec 2026SagittaVisible from 17:23 until 19:15
Highest at 17:23, 42° above W horizon
07 Dec 2026SagittaVisible from 17:23 until 19:07
Highest at 17:23, 41° above W horizon
09 Dec 2026VulpeculaVisible from 17:23 until 19:00
Highest at 17:23, 40° above W horizon
11 Dec 2026VulpeculaVisible from 17:24 until 18:52
Highest at 17:24, 38° above W horizon
13 Dec 2026VulpeculaVisible from 17:24 until 18:45
Highest at 17:24, 37° above W horizon
15 Dec 2026VulpeculaVisible from 17:25 until 18:38
Highest at 17:25, 35° above W horizon
17 Dec 2026VulpeculaVisible from 17:25 until 18:31
Highest at 17:25, 34° above W horizon

A more detailed table of 161P/Hartley-IRAS's position on each night is available here. A diagram of the orbit of 161P/Hartley-IRAS is available here.

Finder chart

The chart below shows the path of 161P/Hartley-IRAS 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 161P/Hartley-IRAS is currently available.

The comet's position at perihelion will be:

Object Right Ascension Declination Constellation Magnitude
Comet 161P/Hartley-IRAS 19h19m10s 19°09'N Sagitta 10.8

The coordinates are given in J2000.0.

The sky on 28 Nov 2026

The sky on 28 November 2026
Sunrise
06:48
Sunset
16:13
Twilight ends
17:53
Twilight begins
05:08


Waning Gibbous

72%

19 days old

Planets
Rise Culm. Set
Mercury 05:15 10:20 15:24
Venus 03:24 08:54 14:23
Moon 19:27 03:16 10:52
Mars 22:36 05:29 12:22
Jupiter 22:16 05:10 12:04
Saturn 13:39 19:45 01:50
All times shown in EST.

Source

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 24 Nov 2024.

Image credit

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

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