The Forgotten Planets

Uranus and Neptune are classified as ice giants, distinct from the gas giants Jupiter and Saturn. Their interiors contain massive amounts of water, ammonia, and methane compressed into exotic states. Only Voyager 2 has visited them — flying past Uranus in 1986 and Neptune in 1989. No dedicated mission has returned since.

Uranus is tilted 98 degrees on its axis, meaning it essentially rolls around the Sun on its side. One pole faces the Sun for 42 years while the other sits in complete darkness. Neptune holds the record for the fastest winds in the solar system, reaching 2,100 km/h.