In mythology, Neptune was the God of the Sea, and the eighth farthest planet from the sun earned that same name because of its rich blue color. Its atmosphere is largely composed of helium and hydrogen with a small portion of methane. The very distinguishable blue color is a result of red light's being absorbed by the methane in the atmosphere, with some additional but not-yet-identified chromospheres that give the clouds a blue tint.
Neptune is one of this solar system’s gas planets, meaning that it has speedy winds confined to bands of latitude instead of longitude, with large storms and vortices. This gas planet’s winds are actually the fastest in the solar system, reaching 2,000 kilometers per hour. Not only is it like the gas planets in characteristics, but it is also one of the largest in the solar system. It is the fourth-largest and farthest planet from the sun, seeing as how Pluto was reclassified as a dwarf planet.
When Voyager 2 visited Neptune, the major feature seen was the Great Dark Spot in the southern hemisphere. It was approximately half the size of Jupiter’s Great Red Spot, which is about the same diameter as Earth. Neptune’s winds blow the Great Dark Spot west at 700 miles per hour. There is also a smaller dark spot in the same hemisphere and a small irregular white cloud that zips around Neptune about every 16 hours and is nicknamed “The Scooter.” There is a theory that “The Scooter” could just be a plume rising from a lower part of the atmosphere, but whatever it really is still remains a mystery.
In 1994, an HST observation showed that the Great Dark Spot had disappeared. It either dissipated or was being covered by some other aspect of the atmosphere. A few months later, though, HST found another new dark spot in the northern hemisphere, thus indicating that Neptune’s atmosphere changed quickly. Some speculate that it is probably because of temperature differences between the top and bottom of the clouds.
Neptune is sometimes dubbed as “The Ice Planet” because it possesses a slushy mix of water, ammonia and methane ices under the atmosphere. The clouds of Neptune are long and bright, so at low northern latitudes, Voyager 2 captured images of cloud streaks casting their shadows below. Neptune also has a set of four rings, but they are narrow and faint. That is mostly because they are basically just dust particles thought to have been created by tiny meteorites smashing into Neptune’s moons. Viewed with ground-based telescopes, the rings appear to be arcs, but from Voyager 2’s perspective they turn out to be bright clumps from the ring system. What exactly causes the bright clumps is unknown.
This planet, eighth farthest from the sun, has an atmosphere like no other. It has features which scientists have not even begun to explain. It has made itself stand out from the other outer planets, and, with its record-breaking winds and strange blue tint, has also become a planet worth investigating.
http://nineplanets.org/neptune.html