Moons
Not every world has the same moons.
Earth has one big moon. Mars has two tiny ones. Jupiter and Saturn have huge families. Here are the moons worth knowing first.
Jupiter has about 90 known moons, and Saturn has even more. The lists grow when someone finds a new small one. These cards are the famous moons, not every rock.
Earth
The Moon
Earth has one big moon. Twelve people walked on it, from 1969 to 1972.
It is about a quarter as wide as Earth, and about 30 Earths away. In April 2026, four people flew around it. They did not land.
Mars
Phobos
One of Mars’s two tiny moons. It is lumpy, and it stays close to Mars.
It is not round like our Moon. It looks more like a potato.
Deimos
Mars’s other moon. It is even smaller, and farther out.
Phobos and Deimos are both much smaller than Earth’s Moon.
Jupiter
Io
Io has live volcanoes. Jupiter’s pull squeezes it and heats the inside.
It is one of Jupiter’s four big moons. You can see those four with a small telescope.
Europa
Europa is covered in ice. There may be an ocean under the ice.
That possible ocean is why spacecraft are going to Jupiter’s moons.
Ganymede
Ganymede is the biggest moon we know. It is wider than the planet Mercury.
It has its own magnetic field. Most moons do not.
Callisto
Callisto is icy and covered in old craters.
It sits farther from Jupiter than Io, Europa, and Ganymede.
Saturn
Titan
Titan has thick air and cold lakes. The lakes are not water.
They are methane and ethane. A probe landed there in 2005.
Enceladus
Enceladus sprays ice into space from cracks near its south pole.
The spray may come from water under the ice.
Uranus
Titania
Titania is the largest moon of Uranus.
Uranus has more than 20 known moons. New small ones can still be found.
Neptune
Triton
Triton orbits Neptune backwards compared with the planet’s spin.
That is a clue it was captured, not born there. It has icy geysers.
Pluto
Charon
Charon is so big that Pluto and Charon spin around a point between them.
Pluto is a dwarf planet, not one of the eight planets. It has five known moons.
Mercury and Venus have no moons. A moon is a world that goes around a planet, or around a dwarf planet like Pluto.