Neptune

Neptune is the eighth and outermost planet in our solar system. It is the fourth-largest planet by diameter and the third-largest by mass; Neptune is 17 times the mass of Earth and is slightly more massive than its near twin Uranus which is 14 Earth Masses, but slightly smaller due to its higher density. The planet is named after the Roman god of the sea. Its astronomical symbol is a stylized version of the god's trident.

Neptune's atmosphere is primarily composed of hydrogen and helium, with traces of methane that account for the planet's blue appearance. Neptune's blue colour is much more vivid than that of Uranus, which has a similar amount of methane, and an unknown component is presumed to cause the intense color. Neptune also has the strongest winds of any planet in the solar system, with estimates as high as 2,500 km/h or 1,500 mph. At the time of the 1989 Voyager 2 flyby, it had in its southern hemisphere a Great Dark Spot comparable to the Great Red Spot on Jupiter.