Neptune has 13 moons; the two largest are Triton and Nereid.
Size: Neptune is slightly smaller than Uranus and has a diameter of 31,000 miles (50,000 kilometers), so about 4 Earths would fit across its face.
Distance from the Sun: Neptune is the eighth planet from the Sun. It orbits at an average distance of 2.8 billion miles (4.5 billion km), thirty times farther than Earth.
Orbit around the Sun: It takes 165 Earth years for Neptune to go around the Sun one time.
Rotation: It takes Neptune only 16 Earth hours for it to spin on its axis once.
Surface: Like the other gas-giant planets, Neptune's "surface" is the top of its deep atmosphere. This contains hydrogen (79 percent), helium (18 percent), and methane (3 percent), which gives the planet its blue color. Neptune's atmosphere has a striped pattern like both Jupiter's and Saturn's.
Temperature: The average temperature at Neptune is 370° F
Escape velocity: To escape Neptune's gravity, you need to travel 52,600 miles (84,700 km) per hour, compared to 25,000 miles (40,200 km) per hour necessary to escape Earth's gravity.
Other information: Six narrow rings encircle Neptune. Because some places have more particles than others, Neptune's rings form arcs around the planet.
Johann Galle and Heinrich D'Arrest discovered Neptune in 1846.
Neptune has 13 moons, the two largest are Triton and Nereid. Triton is made of rock and ice. Its surface is rich in water ice, dry ice, frozen carbon monoxide, methane, and nitrogen. Triton has cold geysers that spit nitrogen instead of the hot water that geysers on Earth release.
Neptune was the Roman god of the oceans.