Moon and Jupiter

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A giant tags along behind the Moon tonight: Jupiter, the largest planet in the solar system. It looks like a brilliant star, and it's a little to the left of the Moon at nightfall. They'll scuttle quite low across the south during the evening and into the wee hours of the morning.

Despite its giant size, there's a lot we don't know about Jupiter. Scientists would like to learn more about its core, the circulation of its deep atmosphere, its powerful magnetic field, and many other parts of the planet.

They hope to get some answers with a spacecraft that's scheduled for launch three years from this month. It's named Juno after Jupiter's mythological wife. It'll be the first mission to head for Jupiter in two decades.

Previous missions revealed quite a lot about the planet. We know, for example, that Jupiter probably has a solid core wrapped inside layers of hydrogen and helium. We know that these layers act like an electric dynamo, producing a magnetic field as the planet spins. And we know that Jupiter's atmosphere is dynamic, with giant storms and globe-circling jet streams.

But many of the details are still sketchy. Exactly how big is the core, for example, and just what is it made of? How deep are the planet's giant storms -- especially the Great Red Spot, which is wider than Earth? And how did Jupiter grow so big?

The answers may come after Juno arrives at Jupiter in 2016.

We'll have more about Jupiter tomorrow.

Script by Damond Benningfield, Copyright 2008

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