Comet

Siding Spring

C/2012 OP (Siding Spring)

Siding Spring is a comet in the Comet orbit class. Its orbit takes it from 3.61 AU to 2,105.42 AU from the Sun; one orbit takes 34,244.2 years. Orbit from the JPL solution of 15 April 2021.

Where is it now

Distance from Sun: 29.197 AU
True anomaly: 139.11°
Distance from Earth: 29.103 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.

Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Siding Spring is 29.103 AU from Earth today (4.0 light-hours).

In the sky

Right ascension: 08h 59m 52s
Declination: +63° 11′ 44″
Constellation: Ursa Major
Distance from Earth: 29.1 AU
Elongation from the Sun: 94.63° — 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.

Paste a location

How do I find my coordinates?

Google Maps on a computer

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

Google Maps on a phone

Press and hold the spot to drop a pin.
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: 1,054.515 AU
Eccentricity: 0.9966
Inclination: 114.83°
Orbital period: 34,244.2 years
Perihelion: 3.607 AU
Aphelion: 2,105.423 AU
Longitude of ascending node: 267.37°
Argument of periapsis: 351.44°
Epoch · J2000: 2456315.5
Orbit class · COM: Comet
Earth MOID · 1,011.8 LD: 2.6 AU
Tisserand (Jupiter): -0.983

Orbit quality

Observations used: 100
Data arc: 381 days
First observed: 16 July 2012
Last observed: 1 August 2013
Residual RMS: 0.39 ″
Solution · Otto Matic: 15 April 2021

Visual & observation

Absolute magnitude (H): 14.4
Total magnitude M₁ · K₁ 4.5: 14.4

Discovery & classification

Also known as 2012 OP

Named

Sources

visual properties: JPL SBDB (lookup)
visual properties: JPL SBDB (lookup)
orbital elements: JPL SBDB