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More Moon and Companions

July 14, 2012

Dawn comes early on these summer mornings. Even so, it’s worth getting up a little early tomorrow to see a spectacular encounter involving the three brightest objects in the night sky: the Moon and the planets Venus and Jupiter. And to make the show even better, the “eye” of the bull looks on.

The group rises a couple of hours before sunrise, and is in pretty good view by first light. Venus is the brilliant “morning star” below the Moon, with Jupiter above the Moon. The bull’s eye — the orange star Aldebaran — is just to the right of Venus.

Through a small telescope, Venus looks like a miniature version of the crescent Moon. It looks that way for the same reason the Moon does — it’s roughly between Earth and the Sun, so most of the planet’s daytime hemisphere us facing away from us. Sunlight illuminates only a small fraction of the side that’s facing Earth.

But while the Moon is moving back toward the Sun, Venus is moving away from the Sun as seen from Earth. So over the coming months, the fraction in sunlight will grow larger. At the same time, though, Venus will be moving farther from us, so it won’t be getting any brighter. In fact, Venus is actually at maximum brightness for its current morning appearance. For the rest of the year, it’ll slowly fade — although not by a whole lot. It’ll still reign as the “morning star” for the rest of the year.

Tomorrow: bright delights in the evening sky.


Script by Damond Benningfield, Copyright 2012


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