Neptune is the eighth planet from the sun. It was discovered in 1846 by JG Galle. It was named after the Roman god of the sea. Though it is the fourth largest planet in the solar system, it is also the smallest gas-ball giant. Neptune's average distance from the sun is 4.5 billion kilometers. Neptune is 30,760 in diameter. Its year is 250 Earth years long. During 20 of those years, it is the last planet. That is caused by Pluto's eccentric orbit. Neptune is called the Windy Planet because it has the strongest winds of all the planets. There, winds can blow up to 2,000 kilometers per hour.
Neptune has eight moons, two can be seen from Earth. Triton, the largest moon, has a surface that looks like a cantaloupe! Triton is also similar to Earth in some ways. When Voyager 2 passed Triton, they noticed that there was nitrogen gas erupting, similar to geysers on Earth.
Neptune's core is made of melted rock, liquid hydrogen, ammonia, methane, and an ocean of water. The atmosphere is made of hydrogen, helium, and methane.
Neptune is covered with layers of clouds. When Voyager 2 visited Neptune, they saw that Neptune has a series of storms. There is the Great Dark Spot, Scooter, and Dark Spot 2. Those are all similar to the Great Red Spot on Jupiter. But a few years later the Great Dark Spot disappeared! This happened because it is so far from the sun. Scientist believe that Neptune's hot core is responsible for all the winds, storms, and weather changes.
When scientists first saw Neptune's rings, they thought the rings were incomplete. They believed that the so-called rings traveled around Neptune in pieces. But when Voyager 2 visited Neptune, photographs showed that Neptune's rings are complete. The only reason they look incomplete from Earth is because they are clumpy, some parts are thick and some parts are very thin.
Neptune's Moons
Neptune's Core and Atmosphere
Neptune's Storms and Weather
Neptune's Rings
