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Jupiter and Uranus

May 31, 2010

Two giant planets are slipping by each other over the next few days. Although one of them is quite faint, the other is so bright that it easily points the way to its bashful companion.

The brighter of the two is Jupiter, the largest planet in the solar system. It's about 11 times the diameter of Earth, and it's more massive than all the other planets and moons put together.

Jupiter rises in the wee hours of the morning, and is well up in the eastern sky at first light. After the Moon, it's the brightest object in the sky at that hour, so it's easy to spot.

The other planet is Uranus, the third-largest planet. It's so far away that it's a bit too faint to see with the unaided eye. But it is visible through binoculars. Tomorrow, it's about one degree to the left of Jupiter -- less than the width of a finger at arm's length. Through binoculars, it looks like a tiny blue-green star.

You'll actually see some comparably bright pinpoints of light huddling quite close to Jupiter -- its four largest moons: Io, Europa, Ganymede, and Callisto. As they orbit the giant planet, their configuration changes each day.

The configuration of Jupiter and Uranus is changing each day, too. Over the next week and a half, Jupiter will slide below Uranus, and move a bit closer to it. That closeness is only an illusion, though: Uranus is almost a billion and a half miles farther than its larger sibling.

More about these giant worlds tomorrow.

Script by Damond Benningfield, Copyright 2010

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