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Moon and Aldebaran

April 10, 2016

The Moon is a ball of solid rock. It’s more than 2,000 miles in diameter, and it’s about one percent as massive as Earth. Yet it may have formed in a hurry. Almost half of it may have clumped together in just a few months, with just about the entire thing assembling within a few centuries.

There’s pretty good agreement that the Moon was born after another planet slammed into Earth when the solar system was about a hundred million years old. Some studies say it was a glancing blow, while others say it was head-on.

In either case, the impact pulverized much of the young Earth and the other body. That created a large disk of gas and molten rock around Earth.

A good bit of the debris fell back to Earth. But material that was far enough away from the planet began clumping together. A recent study, led by Robin Canup of the Southwest Research Institute, says that within a few weeks, the debris had joined to form thousands of “moonlets” — bodies no more than a few miles across. And within a year or so, many of those had come together to form about 40 percent of the bulk of the present-day Moon.

After a brief lull, more material began clumping together. Within a few hundred years, this process had essentially created the full-grown Moon — the world that lights up the night.

And the Moon teams up with the star Aldebaran to light up the sky this evening. Aldebaran is the “eye” of Taurus the bull, and it stands just to the lower right of the Moon.


Script by Damond Benningfield

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