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Comet

Stephan-Oterma

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38P/Stephan-Oterma

Stephan-Oterma is a comet in the Halley-type comet orbit class. Its orbit takes it from 1.59 AU to 20.99 AU from the Sun; one orbit takes 37.93 years. Discovered 22 January 1867 by Coggia, Jerome E.. Orbit from the JPL solution of 4 December 2024.

Where is it now

Distance from Sun
15.942 AU
True anomaly
161.47°
Distance from Earth
16.817 AU
As of
24 October 2026

Two-body Kepler propagation — accurate to ~0.1% for major planets over decades, less so for highly-perturbed bodies. Use JPL Horizons for high precision.

Sun Earth — 0.994 AU from the Sun Earth Stephan-Oterma — 15.942 AU from the Sun Stephan-Oterma
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Stephan-Oterma is 16.817 AU from Earth today (2.3 light-hours).

In the sky

Right ascension
15h 49m 29s
Declination
-14° 22′ 00″
Constellation
Libra
Distance from Earth
16.82 AU
Elongation from the Sun
27.21° — near the Sun — look low at dusk or dawn

Visible from both hemispheres.

From your location

See how high it is right now, whether it is up after civil twilight, and when it rises and sets where you are.

How do I find my coordinates?

Google Maps on a computer

  1. Right-click the spot where you'll be observing.
  2. The first line of the menu is the coordinates, e.g. 51.50722, -0.12758 — click it and they're copied.
  3. Paste them above.

Google Maps on a phone

  1. Press and hold the spot to drop a pin.
  2. The coordinates appear in the search bar (or on the pin's card) — tap to copy, then paste above.

A full Google Maps link works too, but the short maps.app.goo.gl share links don't carry coordinates — copy the numbers instead. We round to about a kilometre; that's all the sky calculation needs.

Know your what3words address? Paste it, e.g. ///filled.count.soap. This is optional — the three words are sent to what3words to convert them, and we don't store the address or the result.

Your location stays in your browser and is sent only for this calculation. Using a what3words address is optional; if you do, the three words go to what3words to be converted and we don't record them. Set a location first, then you can save an email alert for this object. See our privacy policy.

Two-body approximation, good to about a degree for the planets — enough to find the constellation and know whether it is up.

Orbital elements

Semi-major axis
11.289 AU
Eccentricity
0.8593
Inclination
18.35°
Orbital period
37.93 years
Perihelion
1.589 AU
Aphelion
20.99 AU
Longitude of ascending node
78°
Argument of periapsis
359.59°
Epoch · J2000
2458266.5
Orbit class · HTC
Halley-type comet
Earth MOID · 235.5 LD
0.6052 AU
Tisserand (Jupiter)
1.891

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
3,293
Data arc
77.54 years
First observed
6 November 1942
Last observed
21 May 2020
Residual RMS
0.48 ″
Solution · Davide Farnocchia
4 December 2024

Visual & observation

Absolute magnitude (H)
11.6
Total magnitude M₁ · K₁ 9.5
11.6

Discovery & classification

Discovered by
Coggia, Jerome E.
Discovery date
22 January 1867
Discovery site
Marseilles Observatory, France

Also known as 38P · 1867 I · 1942 IX · 1980 X · 1980g · 38P/1867 B1 · 38P/1942 V1 · 38P/1980 L2

Named

Close approaches 5 on record

When (UTC) Body Distance Lunar distances Relative speed
2067-05-14 11:34:00 Urnus 1.5865 AU 617.4 LD 5.4 km/s
2135-10-21 02:04:00 Juptr 1.4617 AU 568.9 LD 11.9 km/s

Next ten from today. 1 lunar distance = 384,400 km. Source: JPL close-approach data.

Sources