Solar System: Outer Planets - Uranus

Planet of the Longest Seasons

Uranus has the distinction of being the first planet discovered in modern times (and with a telescope), in 1781 by William Herschel.

Uranus, the seventh planet from the Sun, is a Jovian planet. Like the other Jovian planets, Uranus has a very thick atmosphere, so we’ve never seen the surface. Unlike Jupiter and Saturn, which have a liquid “surface,” data indicates that Uranus may actually have layers of rock and ice beneath its atmosphere.

Uranus has only been visited by one spacecraft—Voyager 2. From that flyby and other observations, scientists have found 11 very faint rings and 21 moons circling the planet. They expect that there may be more moons yet to be discovered.

Courtesy of NASA JPL

One very odd characteristic is Uranus’s rotation—the planet spins on its side! Uranus’s south pole faces the Sun for 42 Earth years of summer, then turns away from the Sun for 42 Earth years of winter!

Sometimes on very clear nights Uranus is visible with the unaided eye, but usually you’ll need binoculars or a telescope to see this blue, gas planet.

Uranus reaches opposition on August 24, 2003! If you find a very dark observing site and clear skies, you can observe this small, greenish point of light in the constellations Aquarius--without the help of binoculars.