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Comet

Oterma

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39P/Oterma

Where is it now

Distance from Sun
6.994 AU
True anomaly
89.18°
Distance from Earth
7.085 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.

Orbit of Mercury Orbit of Venus Orbit of Mars Sun Earth — 0.994 AU from the Sun Earth Oterma — 6.994 AU from the Sun Oterma
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Oterma is 7.085 AU from Earth today (58.9 light-minutes).

In the sky

Right ascension
08h 52m 14s
Declination
+17° 36′ 24″
Constellation
Cancer
Distance from Earth
7.08 AU
Elongation from the Sun
80.9° — well clear of the Sun

Favours the northern hemisphere; low or below the horizon from far south.

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
7.403 AU
Eccentricity
0.2284
Inclination
1.48°
Orbital period
20.14 years
Perihelion
5.712 AU
Aphelion
9.094 AU
Longitude of ascending node
303.64°
Argument of periapsis
89.7°
Epoch · J2000
2456994.5
Orbit class · CTc
Chiron-type comet
Earth MOID · 1,836.3 LD
4.7185 AU
Tisserand (Jupiter)
3.025

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
287
Data arc
81.73 years
First observed
17 February 1942
Last observed
10 November 2023
Residual RMS
0.39 ″
Solution · Davide Farnocchia
16 January 2024

Visual & observation

Absolute magnitude (H)
6.8
Total magnitude M₁ · K₁ 14.8
6.8

Discovery & classification

Discovered by
Oterma, Liisi
Discovery date
8 April 1943
Discovery site
Turku, Finland

Also known as 39P · 1942 VII · 1958 IV · 39P/1943 G1 · 39P/2001 P3

Named

Close approaches 9 on record

When (UTC) Body Distance Lunar distances Relative speed
2155-02-21 10:28:00 Juptr 0.7712 AU 300.1 LD 0.7 km/s
2168-10-03 00:21:00 Satrn 1.9331 AU 752.3 LD 0.8 km/s

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

Sources