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Comet

MOSS

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C/2012 CH17 (MOSS)

MOSS is a comet in the Comet orbit class. Its orbit takes it from 1.3 AU to 219,314.27 AU from the Sun; one orbit takes 36,313,439.9 years. Orbit from the JPL solution of 15 April 2021.

Where is it now

Distance from Sun
31.521 AU
True anomaly
156.6°
Distance from Earth
30.756 AU
As of
25 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 MOSS — 31.521 AU from the Sun MOSS
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. MOSS is 30.756 AU from Earth today (4.3 light-hours).

In the sky

Right ascension
04h 27m 59s
Declination
-04° 18′ 01″
Constellation
Eridanus
Distance from Earth
30.75 AU
Elongation from the Sun
140.37° — well clear of the Sun

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
109,657.782 AU
Eccentricity
1
Inclination
27.74°
Orbital period
36,313,439.9 years
Perihelion
1.296 AU
Aphelion
219,314.269 AU
Longitude of ascending node
125.98°
Argument of periapsis
137.99°
Epoch · J2000
2456023.5
Orbit class · COM
Comet
Earth MOID · 147.3 LD
0.3786 AU
Tisserand (Jupiter)
1.249

Orbit quality

Observations used
627
Data arc
494 days
First observed
2 February 2012
Last observed
10 June 2013
Residual RMS
0.71 ″
Solution · Otto Matic
15 April 2021

Visual & observation

Absolute magnitude (H)
14
Total magnitude M₁ · K₁ 4.5
14

Discovery & classification

Also known as 2012 CH17

Named

Sources