Our Lucky Moon

Nov 2, 2017

At some point perhaps tonight, perhaps later. We will look up and glance at the moon with indifference. We've seen it a million times before, I mean it's just a hunk of rock very much like our own Earth rock that does happen to have footprints of humans on it. So what? But if there was no moon, ever. What would be different? To start, if we didn't have a moon none of us would probably be here right now. Is that dramatic enough for you?

When the solar system was in it's infancy, the Earth stood alone without a moon. That early solar system though still had a lot of large objects roaming around. And one Mars-sized object hit the pre-moon Earth. It was a glancing blow, but severe enough that it caused the mantles of both objects to merge and throw up a ring of debris that would eventually become our Earth and our moon. When the moon formed it was ten times closer and the Earth was spinning four times faster. This produced tides that moved miles inland and then back every two hours. This triggered the important mixtures of minerals between the land and the sea that ultimately allowed life to establish itself. Without the early moon's influence, the Sun alone would have produced tides only 1/6 as large, and the resulting mixing would have occurred at a much slower rate. Life would have taken perhaps hundreds of millions of years longer to develop.

Since then of course, the Earth has slowed down and the moon has moved farther away. But the next time you look up into a clear night's sky, thank your lucky moon.

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Follow your curiosity to the Fred G. Dale Planetarium at Wayne State College.