Subtle bands of color highlight this Hubble Space Telescope view of Uranus, the solar system's third-largest planet. The cloud bands go up and down because Uranus is tilted on its side. The planet puts on its best showing of the year in early October, although binoculars or a telescope are still needed to see it. [NASA/STScI]
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Uranus at Opposition
Hundreds of planets have been found in other star systems. They’re all so far away, though, that they’re seen as no more than squiggly lines on a computer screen. Yet astronomers are slowly starting to tease details out of some of those squiggles.
To understand how difficult the problem is, consider that there’s still a lot to learn about the planets of our own solar system, even though by astronomical standards they’re just next door.
One mystery, for example, is why the planet Uranus radiates so little energy into space.
The four outermost planets — Jupiter, Saturn, Uranus, and Neptune — are all giants. They’re so heavy that their gravity squeezes their interiors tightly, producing heat that radiates into space. In fact, three of the four worlds emit a good bit more energy than they receive from the Sun. The exception is Uranus, where the energy is roughly balanced — and scientists are trying to figure out why.
Another mystery is the planet’s climate. Uranus orbits the Sun on its side, with each pole receiving 42 years of sunlight followed by 42 years of darkness. Astronomers are watching to see how the planet’s climate changes with the seasons — one of the mysteries of a world in our own neighborhood.
And this is a good time to study Uranus because it’s closest to Earth, so it’s biggest and brightest for the year. Even so, you need binoculars to spot it. It’s low in the east as night falls, in a barren patch of sky.
Script by Damond Benningfield, Copyright 2013