Ice Giant · Farthest Planet

Neptune

The farthest planet from the Sun, Neptune is a dynamic world generating its own internal heat. Despite receiving only 1/900th of Earth's sunlight, it drives the strongest winds in the Solar System - up to 2,100 km/h.

Overview

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Atmosphere composition

Hydrogen 80%
Helium 19%
Methane 1.5%
Hydrogen Deuteride 0.019%
Other traces <0.01%

Notable features

  • Winds up to 2,100 km/h - fastest in the Solar System
  • Great Dark Spot - large storm system (now dissipated)
  • Triton - largest moon, orbits backwards, likely a captured KBO
  • Internal heat source - radiates 2.6× more heat than it receives

Space missions

Mission Year Notes
Voyager 2 1989 Only spacecraft to visit Neptune - 5-hour flyby
Neptune Odyssey 2040s proposed Flagship orbiter and probe concept

NASA images

Images courtesy of NASA Image & Video Library.