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Asteroid

Terpsichore

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81 Terpsichore (A864 SA)

Where is it now

Distance from Sun
3.452 AU
True anomaly
184.68°
Distance from Earth
4.35 AU
As of
21 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 Terpsichore — 3.452 AU from the Sun Terpsichore
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Terpsichore is 4.35 AU from Earth today (36.2 light-minutes).

In the sky

Right ascension
15h 05m 47s
Declination
-22° 45′ 55″
Constellation
Libra
Distance from Earth
4.35 AU
Elongation from the Sun
22.46° — 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
2.852 AU
Eccentricity
0.2116
Inclination
7.8°
Orbital period
4.82 years
Perihelion
2.248 AU
Aphelion
3.455 AU
Longitude of ascending node
0.89°
Argument of periapsis
51.23°
Epoch · J2000
2461200.5
Orbit class · MBA
Main-belt asteroid
Earth MOID · 493.2 LD
1.2673 AU
Tisserand (Jupiter)
3.258

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
8,293
Data arc
161.4 years
First observed
19 November 1864
Last observed
10 April 2026
Residual RMS
0.29 ″
Solution · Otto Matic
5 June 2026

Physical properties

Mean radius
59 km
Rotation period
10.94 hours

Visual & observation

Geometric albedo
0.045
Absolute magnitude (H)
8.66
Colour index (B–V)
0.7
Spectral type (SMASS)
Cb
Spectral type (Tholen)
C
Colour index (U–B)
0.35

Discovery & classification

Discovered by
Tempel, E. W.
Discovery date
30 September 1864
Discovery site
Marseilles

Also known as 81 · A864 SA · 1936 QR · 1936 RK · 1974 LF · A909 AA

Main-Belt Asteroid Named

Sources