Moon and Jupiter

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The Moon takes aim at a giant tonight -- Jupiter, the largest planet in the solar system. They're well up in the south at nightfall, and set in late evening.

There's little about the planet that can't be described with words like giant, grand, or even monumental.

In size, for example, it's a giant. Its diameter is about 11 times greater than Earth's. And it's the heaviest planet, too -- more massive than all the other planets put together.

Because of that great size and heft, it has a grand influence on the rest of the solar system. When the solar system was young, Jupiter probably flung many of the leftover building blocks of the planets out into deep space. Today, it easily deflects passing comets or asteroids -- and sometimes pulls them in, creating massive explosions when they hit the planet.

Jupiter's gravity even has a noticeable effect on the Sun. In fact, if there are astronomers in other star systems with technologies like our own, they'd be able to discover Jupiter through its gravitational pull on the Sun.

And Jupiter's most distinctive feature is a monumental storm known as the Great Red Spot. It's twice as wide as Earth, it packs thousand-mile-an-hour winds, and it's been blowing for centuries.

As befits a planet of superlatives, Jupiter's appearance is big, too. It outshines all the true stars in the night sky. It puts on a grand show -- tonight, to the upper left of the Moon.

More about Jupiter and the Moon tomorrow.

Script by Damond Benningfield, Copyright 2009

For more skywatching tips, astronomy news, and much more, read StarDate magazine.