Facts About Neptune

Neptune is the eighth major planet in our solar system, 17 times more massive than Earth and about four times its diameter.

• The most remote of the four gas giant planets in our solar system, Neptune takes 165 Earth years to orbit the Sun once.
• A “day” on Neptune, however, is only 16 Earth hours.
• Similar to Uranus, Neptune’s cloud-top temperature is a frosty –210°C

Neptune is bluish-green in color, which might seem fitting for a planet named after the Roman god of the sea. However, the color does not come from water; it is due to the gases in Neptune’s atmosphere reflecting sunlight back into space. Neptune’s atmosphere consists mostly of hydrogen, helium, and methane. Below the atmosphere, scientists think there is a thick layer of ionized water, ammonia, and methane ice, and deeper yet is a rocky core many times the mass of Earth.