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Asteroid

Semele

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86 Semele (A866 AA)

Where is it now

Distance from Sun
3.555 AU
True anomaly
140.61°
Distance from Earth
4.488 AU
As of
11 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 — 0.998 AU from the Sun Earth Semele — 3.555 AU from the Sun Semele
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Semele is 4.488 AU from Earth today (37.3 light-minutes).

In the sky

Right ascension
12h 08m 09s
Declination
+03° 16′ 43″
Constellation
Virgo
Distance from Earth
4.49 AU
Elongation from the Sun
18.81° — too close to the Sun to observe

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
3.103 AU
Eccentricity
0.218
Inclination
4.82°
Orbital period
5.47 years
Perihelion
2.427 AU
Aphelion
3.78 AU
Longitude of ascending node
86.04°
Argument of periapsis
308.72°
Epoch · J2000
2461200.5
Orbit class · MBA
Main-belt asteroid
Earth MOID · 558.9 LD
1.4362 AU
Tisserand (Jupiter)
3.179

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
6,004
Data arc
154.3 years
First observed
29 December 1871
Last observed
8 April 2026
Residual RMS
0.37 ″
Solution · Otto Matic
5 June 2026

Physical properties

Mean radius
55 km
Rotation period
16.63 hours

Visual & observation

Geometric albedo
0.056
Absolute magnitude (H)
8.71
Colour index (B–V)
0.7
Spectral type (Tholen)
C
Colour index (U–B)
0.32

Discovery & classification

Discovered by
Tietjen, F.
Discovery date
4 January 1866
Discovery site
Berlin

Also known as 86 · A866 AA · 1978 BB

Main-Belt Asteroid Named

Close approaches 8 on record

When (UTC) Body Distance Lunar distances Relative speed
2066-09-02 14:16:00 Juptr 1.7694 AU 688.6 LD 1.9 km/s
2076-09-14 17:49:00 Juptr 1.7392 AU 676.9 LD 1.4 km/s
2137-12-26 10:29:00 Juptr 1.773 AU 690.0 LD 2 km/s
2148-01-08 15:57:00 Juptr 1.727 AU 672.1 LD 1.4 km/s

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

Sources