The Moon has a beautiful companion tonight. Aldebaran, the “eye” of Taurus, the bull, is close to the upper right of the Moon as they climb into good view in early evening.
The Moon is just past full tonight, so sunlight illuminates almost the entire lunar disk. And down near the bottom of the disk is one of the youngest and brightest features that’s visible to the unaided eye: the crater Copernicus. Binoculars reveal the crater in a bit more detail.
Copernicus formed when a big boulder slammed into the Moon less than a billion years ago, gouging a wide hole in its surface. But scientists didn’t settle on that explanation for the Moon’s craters until a few decades ago. Before then, many believed the craters were really volcanoes.
It turns out that there’s evidence of volcanic activity on the Moon not far from Copernicus. It’s a region that contains more than a dozen big, rounded domes, which probably have a volcanic origin.
Small craters indent the summits of many of these domes, suggesting that the domes may be extinct volcanoes. They might be the same type of volcanoes that built the Hawaiian islands, which build up over time as lava oozes from their summits. On the other hand, they may have formed when molten rock beneath the surface pushed upward, molding the layers of rock above them to form domes.
Either way, the domes tell us that volcanic processes have most likely played some role in shaping the surface of the Moon.
Script by Damond Benningfield, Copyright 2013
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