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More Moon, Saturn, and Spica

March 10, 2012

The face of the Moon is like a celestial yin and yang symbol. One side is serene and calm, while the other is stormy and turbulent.

This dichotomy comes from the names of the Moon’s most prominent features -- the dark volcanic plains known as oceans or seas.

The names were bestowed more than three-and-a-half centuries ago in a map created by two Italian astronomers. They named most of these dark areas for the weather or for states of mind. So most of the features on the eastern hemisphere have calm, soothing names like Sea of Serenity, Sea of Tranquility, and Sea of Nectar. But on the western hemisphere we get the Sea of Clouds, Sea of Rains, and Ocean of Storms.

All of these features are bone dry -- you won’t find a drop of liquid water in any of them. Instead, they’re vast fields of dense volcanic rock. They formed about four billion years ago, when giant asteroids slammed into the lunar surface. Molten rock bubbled to surface to fill the basins created by the impacts. The rock then cooled and hardened -- forming the dark features that we see today.

And most of these features are in good view tonight. As the Moon rises in late evening, the eastern hemisphere is at the top, highlighted by the seas of Serenity and Tranquility. The western hemisphere is at the bottom, highlighted by the large Ocean of Storms. The bright planet Saturn stands close to the upper left of the Moon, with Spica, the brightest star of Virgo, above them.


Script by Damond Benningfield, Copyright 2012


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