Uranus ⛢

Uranus has an atmosphere of roughly 83 percent hydrogen, 15 percent helium, and 2 percent methane. The methane absorbs red light from the Sun and reflects blue-green wavelengths, giving the planet its distinctive cyan color. Deep beneath the atmosphere lies a mantle of water, methane, and ammonia ices surrounding a small rocky core. Uranus is often called an "ice giant" to distinguish it from the gas giants Jupiter and Saturn.

The most striking feature of Uranus is its extreme axial tilt of 97.77 degrees, meaning it essentially orbits the Sun on its side. Scientists believe a collision with an Earth-sized protoplanet billions of years ago may have caused this unusual orientation. Uranus has 13 known rings, which are narrow, dark, and composed primarily of small particles. The planet is also the coldest in the solar system, with minimum atmospheric temperatures reaching -224 degrees Celsius.

Voyager 2 remains the only spacecraft to visit Uranus, flying past in January 1986. During its brief encounter, Voyager 2 discovered 10 new moons, studied the ring system, and measured the planet's magnetic field, which is offset from the center and tilted at 59 degrees relative to the rotational axis. The 2023-2032 Planetary Science Decadal Survey identified a Uranus Orbiter and Probe mission as its highest priority flagship mission, but no such mission has yet been approved.