Neptune

​Neptune and Pluto are the only two planets that can't be seen without a telescope. Galileo observed Neptune when it happened to be near Jupiter, but thought it was just a star in 1613. On August 25, 1989, Voyager 2 visited Neptune. Neptune's best feature is the Great Dark Spot. Neptune is the eighth planet from the sun. Neptune is named after the Roman god of the sea. Neptune's astronomical symbol is, a stylized version of the god Neptune's trident. Neptune's most prominent feature was the Great Dark Spot in the southern hemisphere. It was about half the size of Jupiter's Great Red Spot. Neptune's winds blew the Great Dark Spot westward at 300 meters per second (700 mph). This elliptically-shaped spot (with initial dimensions of 13,000 times 6,600 km, or 8,100 times 4,100 mi) was about the same size as Earth. Neptune is a blue planet.

Neptune's rings are very dark but their composition is unknown. Neptune's blue clouds are mostly made of frozen methane,the main chemical of natural gas. Methane is fuel used for heating and cooking on Earth.

< Neptune's layers.>

Neptune has 13 known moons. They are Triton, Naiad, Thalassa, Despina, Galatea, Larissa, Proteus, Nereid, Halimede, Sao, Laomedeia, Psamathe, and Neso.

Triton is the largest moon of Neptune by far. It's volume is 10,384,000,000 km cubed. It's mass is 2.14 times 10 to the twenty-second power kg. Triton was discovered by the British astronomer named William Lassell on October 10, 1846, just 17 days after Neptune itself was discovered by German astronomers named Johann Gottfried Galle and Heinrich Louis d'Arrest. Triton is named after the Greek god of the sea named Triton, the son of Poseidon (the Greek god comparable to the Roman god Neptune).