List of natural satellites

Irregular moons are probably minor planets that have been captured from surrounding space.

Mercury, the smallest and innermost planet, has no moons, or at least none that can be detected to a diameter of 1.6 km (1.0 mi).

The rings of Saturn are made up of icy objects ranging in size from one centimetre to hundreds of metres, each of which is on its own orbit about the planet.

Neptune has 16 known moons; the largest, Triton, accounts for more than 99.5 percent of all the mass orbiting the planet.

In effect, each orbits the other, forming a binary system informally referred to as a double-dwarf-planet.

Pluto's four other moons, Nix, Hydra, Kerberos and Styx are far smaller and orbit the Pluto–Charon system.

[7] Two objects were named as dwarf planets, under the expectation that they would prove to be so (though this remains uncertain).

A number of other objects in the Kuiper belt and scattered disk may turn out to be dwarf planets.

[9] A number of other smaller objects, such as Huya, Salacia, 2002 UX25, Varda, and 2013 FY27, also have moons, although their dwarf planethood is more doubtful.

As the below graph demonstrates, the maximum absolute magnitude (total inherent brightness, abbreviated H) of moons we have detected around planets occurs at H = 18 for Jupiter, H = 17 for Saturn, H = 14 for Uranus, and H = 12 for Neptune.

Although spacecraft have visited all of these planets, Earth-based telescopes continue to outperform them in moon-detection ability due to their greater availability for wide-field surveys.

Sidereal period differs from semi-major axis because a moon's speed depends both on the mass of its primary and its distance from it.