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Uranus at Opposition II
The largest moon of the planet Uranus has been shrink-wrapped. Early in its history, its outer layers cooled and shrank, while its center warmed and expanded. That gave it a wrinkly crust punctuated by giant cliffs and canyons.
Titania is less than half the size of our own Moon. And it orbits Uranus at about the same distance as the Moon orbits Earth. It’s about half ice and half rock.
Its surface is pockmarked by many impact craters. But its most interesting features are canyons and cliffs. The cliffs are miles high and up to hundreds of miles long. And the canyons are even more dramatic. The longest one yet seen stretches a quarter of the way around Titania.
Planetary scientists say that’s the result of the shrink-wrapping. As Titania was being born, its surface was pelted by big chunks of rock and ice. The impacts warmed its outer layers. When the collisions stopped, the outer layers began to cool. At the same time, the decay of radioactive elements deep within Titania warmed its interior. So the outside shrank, while the inside expanded. That cracked and warped the surface — giving Titania a craggy visage.
And Uranus is putting in its best showing of the year right now. The giant planet lines up opposite the Sun, so it rises at sunset and is in view all night, in the constellation Pisces. Tonight, it’s not far to the lower left of the Moon. It’s so faint, though, that you need binoculars or a telescope to see it.