This page lists 13 moons that start with the letter A, spanning from “Adrastea” to “Autonoe.” They belong mostly to Jupiter and Saturn, though one orbits Uranus. These moons range enormously in size, from moonlets smaller than a city block to worlds hundreds of kilometers wide. Studying them helps scientists understand ring systems, planetary gravity, and how the outer solar system formed.
Moons are natural satellites that orbit a planet, held in place by gravity rather than orbiting the Sun on their own. Our solar system holds hundreds of them, and new ones are still being discovered today. Among the most famous are Jupiter’s four large moons, first spotted by Galileo in 1610, which changed how people understood the cosmos.
Below you’ll find the table with Moon, Parent Planet, Diameter (km), Discovery Year, and Description.
Moon: The official name of each moon, so you can identify it and search for more information about it.
Parent Planet: The planet each moon orbits, helping you place it within the right part of the solar system.
Diameter (km): The approximate width of each moon in kilometers, letting you compare sizes across very different bodies.
Discovery Year: The year each moon was first confirmed, showing you how our knowledge of these objects has grown over time.
Description: A short summary of each moon’s key traits, orbit, and history, giving you the essential facts in one place.
Moons
Moon
Parent Planet
Diameter (km)
Discovery Year
Adrastea
Jupiter
16
1979
Aegaeon
Saturn
0.5
2008
Aegir
Saturn
6
2000
Aitne
Jupiter
3
2001
Albiorix
Saturn
32
2000
Amalthea
Jupiter
167
1892
Ananke
Jupiter
28
1951
Anthe
Saturn
2
2004
Aoede
Jupiter
4
2001
Arche
Jupiter
3
2002
Ariel
Uranus
1,158
1851
Atlas
Saturn
30
1980
Autonoe
Jupiter
4
2001
Descriptions
Adrastea
A tiny inner moon of Jupiter that orbits just outside the planet’s main ring and is thought to supply material to it. Discovered by Voyager 2, it is one of the smallest known moons in the solar system.
Aegaeon
A moonlet embedded within Saturn’s bright G ring, Aegaeon is one of the smallest confirmed moons in the solar system. It was spotted by the Cassini spacecraft and is thought to replenish ring particles.
Aegir
A small irregular moon in Saturn’s Norse group that follows a distant retrograde orbit around the planet. Named after a sea giant in Norse mythology.
Aitne
A tiny irregular moon of Jupiter in the retrograde Ananke group, named after a daughter of Aeolus in Greek myth. It orbits far from Jupiter in a tilted, elongated path.
Albiorix
The largest moon in Saturn’s Gallic group of irregular satellites, named after a giant in Gaulish legend. It travels in a distant prograde orbit far beyond Saturn’s main ring system.
Amalthea
Jupiter’s largest inner moon and the first Jovian moon discovered since Galileo’s four, Amalthea has a reddish, potato-like shape. It was found by E.E. Barnard and orbits close to Jupiter within its ring system.
Ananke
A small irregular moon of Jupiter and namesake of a family of retrograde satellites sharing similar orbits. Named after the Greek goddess of inevitability, it was discovered by Seth Nicholson.
Anthe
One of Saturn’s smallest known moons, Anthe orbits in the region of the E ring and is gravitationally nudged by the nearby moon Mimas. It was detected by the Cassini mission.
Aoede
A very small irregular outer moon of Jupiter in the Ananke group, named after a Muse of song in Greek mythology. It travels in a retrograde orbit at a great distance from Jupiter.
Arche
A tiny irregular moon of Jupiter in the Ananke group, named after a Muse in Greek mythology. It was discovered in 2002 and follows a retrograde orbit far from Jupiter.
Ariel
The fourth-largest moon of Uranus, Ariel has a surface covered in craters and cut by deep valleys and smooth plains, suggesting past geological activity. Discovered by William Lassell, it is named after a spirit in Shakespeare’s The Tempest.
Atlas
A small inner moon of Saturn that shepherds the outer edge of the planet’s A ring. Its distinctive flying-saucer shape comes from a thick ridge of ring material that has accumulated around its equator.
Autonoe
A small irregular outer moon of Jupiter in the Ananke group, named after a figure in Greek mythology. It orbits Jupiter in a retrograde direction at a large distance from the planet.
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