Venus Shines Bright

StarDate: February 12, 2009

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The planet Venus is putting on its most dazzling show of the year over the next couple of weeks. The "evening star" stands high in the west at nightfall, and remains in view for several hours. And it's brightest for the year, too -- more than 20 times brighter than Sirius, the brightest star in the night sky.

Venus is always bright and showy. It's better than usual right now, though, for a combination of reasons -- its distance from Earth and the Sun, and its angle relative to both of them.

As Venus moves in its orbit, it shows phases, just as the Moon does. It's a fat crescent right now.

The crescent Moon isn't very bright, but a crescent Venus is. That's because the Moon is roughly the same distance away from Earth no matter what its phase is. But the distance to Venus varies by more than a hundred million miles. Right now, the planet is drawing closer to us. So even though we see only a sliver of the planet's sunlit portion, that sliver actually looks quite large. Next week, in fact, the sunlit portion of Venus will cover a larger area of the sky than at any other time for its current evening appearance.

One other thing helps Venus look brighter. As the planet gets closer to Earth, a greater portion of the sunlight that strikes Venus is reflected our way.

So when you add up all the factors, Venus shines at its best -- lighting up the western evening sky for several hours after sunset.

Script by Damond Benningfield, Copyright 2008

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