Natural satellites or moons orbit some of the planets of the solar system. The Moon is Earth's only natural satellite. However, some planets have more than one moon. Jupiter has the most moons of any planet in the solar system.
Planets and Their Satellites
Moons of Jupiter
Jupiter has 79 moons. Of these, 72 have confirmed orbits and 52 have been named. The largest moons are known as the Galilean moons having been discovered by Galileo Galilei in 1610. These are Io, Europa, Ganymede, and Callisto. Ganymede, the largest moon in the solar system, is so massive in size that it exceeds even the planet Mercury. The Amalthea group or inner satellites consist of Metis, Adrastea, Amalthea, and Thebe. The remaining moons are classified as irregular satellites.
Moons of Saturn
Saturn comes in second with 62 moons of which Titan is the biggest and Rhea second. Saturn has 24 regular moons and 38 irregular moons. 53 of Saturn's moons have been named. Titan is the second largest moon in the solar system and is also larger than the planet Mercury.
Moons of Uranus
Uranus is third with 27 moons of which Titania is the biggest with a coplanar orbit. There are 13 inner moons and 9 irregular moons.
Moons of Neptune
Neptune is fourth with 14 moons of which Triton is the biggest, orbiting in a backward pattern known a retrograde orbit. There are a further seven regular moons and six irregular moons.
Moons of Pluto
Pluto, one of the dwarf planets, has 5 moons. These are Charon, Nix, Hydra, Kerberos, and Styx. Charon is by far the largest of Pluto's planets.
Moon of Mars
Mars has 2 moons. They are Phobos and Deimos named after Greek mythology characters.
Moons of Haumea
Haumea, a dwarf planet, also has 2 moons. These are Hi’iaka and Namaka named after Hawaiian goddesses.
Earth has just one moon, known as the Moon. Although it is the fifth largest moon in the solar system, it is the largest moon relative to the planet it orbits.
Makemake, a dwarf planet, also has 1 moon, named MK 2.
Eris, the second largest dwarf planet, also has 1 moon named Dysnomia which orbits in a circular pattern. The moon was named for Dysnomia, the Greek goddess of lawlessness, as she is the daughter Eris, the Greek goddess of strife and discord.
Planets without Moons
Mercury, Venus, and the dwarf planet Ceres are the only planets in the solar system without any moons.
Human Exploration of Various Moons
The most famous space missions to a natural satellite were to our own moon. On September 14, 1959, the Russian Space program successfully launched spacecraft Luna 2 to land on the moon. Then, in 1966, Luna 9 also landed on the moon. Luna 10 entered the moon’s orbit for 60 days on March 31, 1966. The US Space program began its launch of the Apollo moon missions from 1968 to 1972. Apollo 8 and Apollo 10 orbited the moon. In July 1969, US astronaut Neil Armstrong became the first man to walk on the moon during the Apollo 11 mission. The Russian Space program also launched several more unmanned missions to the moon that took rock samples from the moon. China, India, Luxembourg, and Japan have also launched several more recent lunar missions.
Future unmanned and robotic missions are planned in conjunction with other nations to further explore the moon. Private entities and companies have also announced plans to launch their own missions including tourist flights. However, more exciting unmanned moon missions have already been launched to explore far moons in our solar system. NASA launched its Galileo mission on October 18, 1989, to study Jupiter’s moons. On July 14, 2015, the US spacecraft New Horizon flew by Pluto and its moon Charon to send back amazing photographs. On June 30, 2004, the US spacecraft Cassini dropped a probe into Titan, one of Saturn’s moons.