Moon and Jupiter

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The Moon and the planet Jupiter huddle close early tomorrow. They're side by side at first light; Jupiter's to the left of the Moon, and looks like a brilliant star.

The Moon is a crescent right now. It's nighttime across most of the hemisphere that faces our way, with sunlight bathing only a sliver of the lunar disk.

That sliver is growing smaller by the day, because the Moon will soon pass between Earth and the Sun -- the time of "new" Moon.

As the Sun sets on the Moon, it creates some striking patterns of light and shadow. There's no atmosphere on the Moon to scatter the sunlight, so the shadows have a sharp edge. But the shadows on the lunar nearside aren't completely dark because they're bathed in earthshine -- a patina of sunlight reflected off of Earth.

The process of sunset on the Moon is leisurely. On Earth, it takes only a couple of minutes from the time the Sun touches the horizon until it disappears from view. But the Moon spins slower than Earth does, so it takes almost an hour for the Sun to drop from sight.

The sky would remain black on the airless Moon. But you might see the Sun look a little redder as it nears the horizon, perhaps flanked by a thin band of color. Radiation from the Sun could give the powdery lunar soil an electric charge, causing some dust to actually float above the surface. If so, then sunlight passing through the dust would look a little redder -- just like the setting Sun right here on Earth.

Script by Damond Benningfield, Copyright 2008

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