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Comet

Mueller

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120P/Mueller 1

Where is it now

Distance from Sun
5.295 AU
True anomaly
204.01°
Distance from Earth
6.18 AU
As of
22 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 — 0.995 AU from the Sun Earth Mueller — 5.295 AU from the Sun Mueller
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Mueller is 6.18 AU from Earth today (51.4 light-minutes).

In the sky

Right ascension
15h 18m 56s
Declination
-24° 36′ 00″
Constellation
Libra
Distance from Earth
6.18 AU
Elongation from the Sun
24.61° — near the Sun — look low at dusk or dawn

Favours the southern hemisphere; low or below the horizon from far north.

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
4.136 AU
Eccentricity
0.3365
Inclination
8.79°
Orbital period
8.41 years
Perihelion
2.744 AU
Aphelion
5.527 AU
Longitude of ascending node
4.44°
Argument of periapsis
30.01°
Epoch · J2000
2454349.5
Orbit class · JFc
Jupiter-family comet (P < 20 y)
Earth MOID · 682.4 LD
1.7536 AU
Tisserand (Jupiter)
2.917

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
147
Data arc
34.14 years
First observed
18 October 1987
Last observed
9 December 2021
Residual RMS
0.79 ″
Solution · Otto Matic
14 February 2022

Physical properties

Mean radius
1.50 km

Visual & observation

Absolute magnitude (H)
6.6
Total magnitude M₁ · K₁ 26.3
6.6

Discovery & classification

Discovered by
Mueller, Jean
Discovery date
18 October 1987
Discovery site
Palomar Mountain Observatory, California

Also known as 120P · 120P/1987 U2 · 120P/1987a1 · 120P/1995 O2 · 1987 XXXI

Named

Close approaches 13 on record

When (UTC) Body Distance Lunar distances Relative speed
2038-10-15 09:09:00 Juptr 1.8203 AU 708.4 LD 2.5 km/s
2042-04-05 09:33:00 Juptr 1.0999 AU 428.1 LD 4.9 km/s
2100-03-28 15:23:00 Juptr 0.4588 AU 178.6 LD 3.8 km/s
2100-03-28 15:23:00 Jupiter 0.4588 AU 178.6 LD 3.8 km/s
2124-01-16 08:22:00 Juptr 1.7535 AU 682.4 LD 7.5 km/s
2184-10-20 02:30:00 Juptr 0.4328 AU 168.4 LD 3.5 km/s
2184-10-20 02:30:00 Jupiter 0.4328 AU 168.4 LD 3.5 km/s

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

Sources