Eighth and outermost planet, a deep-blue ice giant with the fastest winds in the Solar System, discovered through mathematical prediction.
Core Principles & Analysis
Neptune was found in 1846 within one degree of the position Urbain Le Verrier calculated from irregularities in Uranus's orbit.
Its winds reach about 2,100 km/h, the fastest measured on any planet.
Its largest moon Triton orbits backward, marking it as a captured Kuiper Belt object, and Voyager 2 photographed nitrogen geysers erupting from its surface.