🔵 Uranus: The Tilted Ice Giant

Uranus is the seventh planet from the Sun, an ice giant tipped over on its side -- its axis is tilted about 98 degrees, meaning it essentially rotates on its side relative to its orbit, likely the result of a massive ancient collision.

A Planet on Its Side

Uranus's extreme axial tilt means its poles, rather than its equator, point almost directly at the Sun for part of its 84-year orbit, creating seasons unlike any other planet -- each pole experiences roughly 21 years of continuous sunlight followed by 21 years of continuous darkness.

An Ice Giant

Unlike Jupiter and Saturn's mostly hydrogen-helium composition, Uranus and Neptune are classified as 'ice giants,' containing a higher proportion of heavier volatile compounds -- water, ammonia, and methane ices -- surrounding a rocky core. Methane in its upper atmosphere absorbs red light, giving Uranus its pale blue-green color.

The Coldest Planetary Atmosphere

Despite not being the farthest planet from the Sun, Uranus has the coldest atmospheric temperatures recorded of any planet in the solar system, dropping to about -224°C (-371°F) -- colder even than more distant Neptune, for reasons not yet fully understood.

A Single Visit

Uranus has been visited by only one spacecraft: NASA's Voyager 2, which flew by in January 1986, providing nearly all of the close-up data scientists have about the planet, its faint ring system, and its 27 known moons. No dedicated orbiter mission has ever been sent, though a Uranus orbiter has been identified as a top scientific priority for future exploration.

Frequently Asked Questions

Why does Uranus rotate on its side?

The leading explanation is that a massive collision with another planet-sized body, early in the solar system's history, knocked Uranus onto its side -- though the exact details of this event remain an active area of research.

Does Uranus have rings?

Yes. Uranus has a faint ring system, discovered in 1977 -- far fainter and less extensive than Saturn's, made of dark, narrow rings.

Has any spacecraft orbited Uranus?

No spacecraft has ever orbited Uranus. The only visit was a brief 1986 flyby by NASA's Voyager 2, which remains the sole source of close-up data about the planet.