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spin and orbit

Uranus's spin axis is tilted so far (98°) from the vertical that it lies almost within the plane of Uranus's orbit. This means that from Earth the planet is seen pole-on, side-on, or in between, as its poles and equator face the Sun during the course of its 84-year-long orbit. A collision with a planet-sized body in the distant past probably knocked young Uranus into its sideways position.

NORTHERN WiNTER SOLSTiCE

EQUiNOX

Uranus orbits Sun in 84 Earth years

EQuiNOX

orbit and spin

Uranus appears to orbit the Sun on its side. Its long orbit and high tilt mean each hemisphere faces the Sun for about 42 years at a time.

NORTHERN WiNTER SOLSTiCE

Uranus orbits Sun in 84 Earth years

EQuiNOX

NORTHERN SUMMER SOLSTiCE

axis tilts from vertical by 98c

NORTHERN SUMMER SOLSTiCE

axis tilts from vertical by 98c the rings and moons

Eleven rings, separated by wide gaps, surround Uranus. They are made of dark carbon-rich pieces of material ranging from dust to possibly a few yards across. At least 27 moons orbit Uranus; more probably exist. Five are major moons, dark, rocky bodies with icy surfaces. The rest are much smaller, mainly dozens of miles across.

surface of ariel

Ariel is about a third the size of Earth's Moon and orbits Uranus every two-and-a-half days. It was discovered from Earth but is only seen in detail thanks to Voyager 2. Long, broad faults cut across the moon's icy surface.

false-color view of rings

The bright, colorless ring (far right) is Uranus's outermost ring. Five more rings, colored blue-green, and three, off-white, are to its left.

observing uranus

Uranus is twice as far from the sun as its inner neighbor, Saturn. Its great distance makes it difficult to see, but at magnitude 5.5, it is just visible with the naked eye. It looks like a star to the eye or through basic binoculars. More powerful ones or a small telescope will show it as a disk. Following the planet's slow progress against the background stars will confirm its identity.

uranus in the night sky

The disk of Uranus and the planet's five major moons—Ariel, Umbriel, Oberon, Titania, and Miranda—are visible here through an Earth-based telescope. The blue coloring of the featureless globe is unmistakable.

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