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Public Universe
Moon

Phobos

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Orbits Mars Wikipedia ↗

Where is it now

Distance from Sun
1.574 AU
True anomaly
115.7°
Distance from Earth
1.555 AU
As of
14 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 — 0.997 AU from the Sun Earth Mars — 1.574 AU from the Sun Mars
Phobos is shown at its parent, Mars. Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Mars is 1.555 AU from Earth today (12.9 light-minutes).

In the sky

Right ascension
08h 48m 24s
Declination
+19° 09′ 05″
Constellation
Cancer
Distance from Earth
1.55 AU
Elongation from the Sun
72.79° — well clear of the Sun

Favours the northern hemisphere; low or below the horizon from far south.

Shown at its parent's position — a moon sits within a fraction of a degree of its planet.

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.

Parent-body proxy (planet-mars), not an independent position of this moon. 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
0 AU
Eccentricity
0.0151
Inclination
1.09°
Orbital period
7.7 hours
Perihelion
0 AU
Aphelion
0 AU
Longitude of ascending node
169.2°
Argument of periapsis
216.3°
Epoch · J2000
J2000

Physical properties

Mean radius
11 km
Mass
1.066 × 10¹⁶ kg
Density
1.876 g/cm³
Rotation period
7.65 hours
Axial tilt
0°
GM
0.001 km³/s²

Visual & observation

Geometric albedo
0.071
Representative colour
#7A6A5F

Discovery & classification

Discovered by
Asaph Hall
Discovery date
18 August 1877

Sources