What is Neptune?

Overview

Neptune, the eighth planet from the Sun, is a distant ice giant known for its deep blue color and fierce winds, located at the edge of the classical planets.

  • Diameter: 49,244 km
  • Distance from Sun: 4.5 billion km
  • Mass: 1.02 x 10²⁶ kg
  • Orbit Period: 164.8 years
  • Rotation Period: 16.11 hours
Neptune from Voyager 2

Image credit: NASA/JPL

Details

Atmosphere: Mostly hydrogen (80%) and helium (19%), with methane (1%) giving it a blue hue; winds reach up to 2,100 km/h.

Moons: 14 known moons, including Triton, a geologically active moon with geysers.

Surface: No solid surface—just a thick layer of icy water, ammonia, and methane over a rocky core.

Exploration: Visited only by Voyager 2 in 1989, which captured its dynamic storms and faint rings.

Fun Fact: Neptune's Great Dark Spot, a massive storm, disappeared and reappeared over years.