The Planet of Doubt Jupiter and Saturn and on the surface of Uranus itself. At the time "The Planet of Doubt" takes place at the turn of the 22nd century, the limited range of the spaceships ensures that Uranus can only be reached from the American base on Titan when Saturn reaches conjunction with Uranus, an event that occurs once every forty years. The Young expedition explored the planet's south pole in 2060; now Hammond takes his ship, the "Gaea", to the north pole. Finding an ocean at the north pole, Hammond sends the "Gaea" spiraling southeast until they reach land. They find the
Atmosphere of Uranus bright tropospheric clouds are rare on Uranus, probably due to sluggish convection in the planet's interior. Nevertheless, observations of such clouds were used to measure the planet's zonal winds, which are remarkably fast with speeds up to 240 m/s. Little is known about the Uranian atmosphere as to date only one spacecraft, "Voyager 2", which passed by the planet in 1986, obtained some valuable compositional data. No other missions to Uranus are currently scheduled. Although there is no well-defined solid surface within Uranus's interior, the outermost part of Uranus's gaseous envelope (the region accessible to remote sensing) is called its