Moon and Planets
If you find today a little bit taxing, then soothe those troubled nerves by stepping outside a little after sunset and looking for the crescent Moon and two planetary companions. They form a beautiful grouping low in the western sky.
The brightest of those companions is Venus, the "evening star," to the Moon's upper left. The other is Mercury. It's only a fraction as bright as Venus, but it's only about a degree below the Moon -- less than the width of a finger held at arm's length.
Mercury is sliding between Earth and the Sun, so it's looping closer to Earth. It's more than 30 million miles closer today than it was at the first of the month.
Mercury moves so quickly because it's the closest planet to the Sun. Closer planets "feel" the Sun's gravity more strongly, so they move faster in their orbits. Mercury, for example, moves about 40,000 miles an hour faster than Earth does.
As a result, the planet zips across the sky in a hurry. It moves from evening sky to morning sky every few weeks. That quick pace made naming the planet a no-brainer. It's named for the Roman messenger god, who flitted across the sky with wings on his heels -- the winged heels of Mercury.
Look for the speedy planet just below the Moon tonight. It'll pop into view about a half-hour after sunset. The Moon, Mercury, and Venus all set about an hour to an hour and a half later. They'll be in view again tomorrow night, but with the Moon well above Venus.
Script by Damond Benningfield, Copyright 2010
For more skywatching tips, astronomy news, and much more, read StarDate magazine.