20,370 days ago
Dominic Ford, Editor
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Comet 38P/Stephan-Oterma will make its closest approach to the Sun on 31 December, at a distance of 1.58 AU.
From South El Monte on the day of perihelion it will be visible between 19:29 and 05:50. It will become accessible at around 19:29, when it rises to an altitude of 21° above your eastern horizon. It will reach its highest point in the sky at 00:39, 77° above your southern horizon. It will become inaccessible at around 05:50 when it sinks below 21° above your western horizon.
The events that comprise the 1969–1970 apparition of 38P/Stephan-Oterma are as follows:
| Date | Event |
The table below lists the times when 38P/Stephan-Oterma will be visible from South El Monte day-by-day through its apparition:
| Date | Constellation | Comet visibility |
| 24 Oct 2018 | Gemini | Visible from 00:28 until 06:02 Highest at 05:23, 72° above S horizon |
| 26 Oct 2018 | Gemini | Visible from 00:23 until 06:04 Highest at 05:19, 72° above S horizon |
| 28 Oct 2018 | Gemini | Visible from 00:18 until 06:06 Highest at 05:16, 73° above S horizon |
| 30 Oct 2018 | Gemini | Visible from 00:13 until 06:07 Highest at 05:13, 73° above S horizon |
| 01 Nov 2018 | Gemini | Visible from 00:09 until 06:09 Highest at 05:09, 74° above S horizon |
| 03 Nov 2018 | Gemini | Visible from 00:04 until 06:10 Highest at 05:06, 74° above S horizon |
| 05 Nov 2018 | Gemini | Visible from 22:59 until 05:12 Highest at 04:02, 75° above S horizon |
| 07 Nov 2018 | Gemini | Visible from 22:53 until 05:14 Highest at 03:58, 76° above S horizon |
| 09 Nov 2018 | Gemini | Visible from 22:48 until 05:15 Highest at 03:54, 76° above S horizon |
| 11 Nov 2018 | Gemini | Visible from 22:42 until 05:17 Highest at 03:51, 77° above S horizon |
| 13 Nov 2018 | Gemini | Visible from 22:37 until 05:19 Highest at 03:47, 78° above S horizon |
| 15 Nov 2018 | Gemini | Visible from 22:31 until 05:20 Highest at 03:43, 78° above S horizon |
| 17 Nov 2018 | Gemini | Visible from 22:25 until 05:22 Highest at 03:39, 79° above S horizon |
| 19 Nov 2018 | Gemini | Visible from 22:19 until 05:24 Highest at 03:34, 80° above S horizon |
| 21 Nov 2018 | Gemini | Visible from 22:13 until 05:25 Highest at 03:30, 81° above S horizon |
| 23 Nov 2018 | Gemini | Visible from 22:07 until 05:27 Highest at 03:26, 81° above S horizon |
| 25 Nov 2018 | Gemini | Visible from 22:00 until 05:29 Highest at 03:21, 82° above S horizon |
| 27 Nov 2018 | Gemini | Visible from 21:54 until 05:30 Highest at 03:16, 83° above S horizon |
| 29 Nov 2018 | Gemini | Visible from 21:47 until 05:32 Highest at 03:11, 84° above S horizon |
| 01 Dec 2018 | Gemini | Visible from 21:40 until 05:34 Highest at 03:06, 85° above S horizon |
| 03 Dec 2018 | Gemini | Visible from 21:32 until 05:35 Highest at 03:01, 86° above S horizon |
A more detailed table of 38P/Stephan-Oterma's position on each night is available here. A diagram of the orbit of 38P/Stephan-Oterma is available here.
Finder chart
The chart below shows the path of 38P/Stephan-Oterma 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 38P/Stephan-Oterma is currently available.
The comet's position at perihelion will be:
| Object | Right Ascension | Declination | Constellation | Magnitude |
| Comet 38P/Stephan-Oterma | 07h26m10s | 21°55'N | Gemini | 10.0 |
The coordinates are given in J2000.0.
The sky on 9 Oct 2025
| The sky on 9 October 2025 | ||||||||||||||||||||||||||||||||||
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82% 18 days old |
All times shown in PDT.
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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 29 Sep 2025.
Image credit
© Andy Roberts 1997. Pictured comet is C/1995 O1 Hale-Bopp.