#Io moon diameter in km plus#

Photos of the planet, moons and rings, left over from the 1981 Saturn flyby by Voyager 2, had been filed away at NASA's Ames Research Center in Mountain View, California, for a decade. It was Saturn's 18th and most distant moon. A new moon only 12 miles in diameter was discovered in 1990 circling the planet Saturn. Triton had been thought to have a diameter of 2,361 miles, close in size to Earth's Moon, but turned out to be smaller, around 1,690 miles. With a surface temperature of –391 degrees, Triton was found by Voyager 2 to have a thin veneer of methane and nitrogen on top of water ice on its surface. Before Voyager 2, astronomers knew Neptune had two moons, Triton and Nereid. Names are assigned by the nomenclature committee of the International Astronomical Union (IAU). The names Galatea and Larissa were controversial since asteroids previously had been given those names. In 1991, they were named Naiad, Thalassa, Despina, Galatea, Larissa, Proteus. They ranged in diameter from 33 miles to 250 miles. The interplanetary probe Voyager 2 in 1989 found six previously-unknown moons orbiting Neptune. Earth's Moon is second in that comparison. Charon is the moon closest in size to its planet, Pluto. There may be tiny moons as small as only around a mile across. The smallest moon is Deimos, at Mars, only seven miles in diameter, although its size now is rivaled by the small shepherd moons discovered by Cassini at Saturn and by others yet to be counted and named in the rings around Jupiter, Saturn and other giant gas planets in the outer Solar System. The NASA JPL team wondered if S/2004 S1 might not be an object called S/1981 S14 that had turned up in a 1981 Voyager image. The newly discovered bodies were labeled S/2004 S1 and S/2004 S2. The moons are 120,000 miles and 131,000 miles from the center of planet Saturn between the moons Mimas and Enceladus. Previously, the smallest moons seen around Saturn were are about 12 miles across. That's smaller than the city of Boulder, Colorado. The tiny natural satellites are about 2 miles and 2.5 miles in diameter. They turned out to be the smallest bodies seen until then around the ringed planet. When the Cassini spacecraft from Earth arrived at Saturn in 2004, it promptly found two previously unseen moons.

#Io moon diameter in km plus#

Triton, Nereid, Naiad, Thalassa, Despina, Galatea, Larissa, Proteus, plus others yet to receive names Titan, Rhea, Iapetus, Dione, Tethys, Enceladus, Mimas, Hyperion, Prometheus, Pandora, Phoebe, Janus, Epimetheus, Helene, Telesto, Calypso, Atlas, Pan, Ymir, Paaliaq, Siarnaq, Tarvos, Kiviuq, Ijiraq, Thrym, Skadi, Mundilfari, Erriapo, Albiorix, Suttung, plus others yet to receive namesĬordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Belinda, Puck, Miranda, Ariel, Umbriel, Titania, Oberon, Caliban, Sycorax, Prospero, Setebos, Stephano, Trinculo, plus others yet to receive names

Io, Europa, Ganymede, Callisto, Amalthea, Himalia, Elara, Pasiphae, Sinope, Lysithea, Carme, Ananke, Leda, Metis, Adrastea, Thebe, Callirrhoe, Themisto, Kalyke, Iocaste, Erinome, Harpalyke, Isonoe, Praxidike, Megaclite, Taygete, Chaldene, Autonoe, Thyone, Hermippe, Eurydome, Sponde, Pasithee, Euanthe, Kale, Orthosie, Euporie, Aitne, plus others yet to receive names Saturn's moon Titan is the second largest in the Solar System with a diameter of 3,200 miles, half again as large as Earth's Moon. The largest moon is Ganymede with a diameter of 3,280 miles, even larger than either of the planets Mercury and Pluto. It is the only moon close enough to us that details of its surface can be seen through a telescope from Earth. The Moon is one of the larger natural satellites with a diameter of 2,160 miles. Pictures taken by the Hubble Space Telescope suggest there may be even more moons around those outer planets.Įarth's Moon. By comparison, Earth has one moon and Mars has two. Only Mercury and Venus do not have any moons. There also are many small moons that may be asteroids captured by their planets. Several moons are larger than the planet Pluto and two moons are larger than the planet Mercury. Almost 140 moons are known in the Solar System. While moons vary in size, each moon is much smaller than its planet. A moon is a natural satellite rotating around a planet.