Moon, Regulus, and Saturn

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• 296 of 1997
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The Moon and a couple of bright companions -- the star Regulus and the planet Saturn -- climb the eastern sky before dawn tomorrow.

Regulus stands almost directly above the Moon. It's the "heart" of Leo, the lion. It's more than 75 light-years away, so the light we see from it tonight actually left the star during the Great Depression. To understand just how far away that is, keep in mind that in just one second, light travels far enough to circle Earth more than seven times.

Saturn is a little to the lower left of the Moon. It's almost exactly as bright as Regulus, although it has a bit of a golden color.

On the scale of the solar system, Saturn is a long way away -- close to a billion miles. But compared to Regulus and the other stars, it's a next-door neighbor -- light from Saturn reaches Earth in just an hour and a half.

That's not all that long. But it means that any spacecraft at Saturn -- like the current Cassini orbiter -- has to handle a lot of things on its own. If a problem crops up, it takes three hours for word to reach Earth and any commands to get back to the craft. So when any major problem happens, Cassini basically goes to sleep. It reports the problem, then shuts down many of its systems while it waits for instructions from its distant home.

Look for the Moon and its far-flung companions beginning in the wee hours of the morning. They're well up in the east-southeast at the crack of dawn.

Script by Damond Benningfield, Copyright 2008

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