Neptune
Neptune is the eighth and farthest-known Solar planet from the
Sun. In the Solar System, it is the fourth-largest planet by
diameter, the third-most-massive planet, and the densest giant
planet. It is 17 times the mass of Earth, more massive than
its near-twin Uranus.
Source:
Wikipedia
Neptune's internal structure resembles that of Uranus. Its
atmosphere forms about 5% to 10% of its mass and extends
perhaps 10% to 20% of the way towards the core. Increasing
concentrations of methane, ammonia and water are found in the
lower regions.
Source:
Wikipedia
Neptune's atmosphere is 80% hydrogen and 19% helium. A trace
amount of methane is also present. Prominent absorption bands
of methane exist at wavelengths above 600 nm, in the red and
infrared portion of the spectrum.
Source:
Wikipedia
