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How the Moon was Born
The Solar System >
Go out this evening and look down. There under your feet is the crust of the earth. It is a solid part of our planet, globally broken into a dozen monstrous plates only miles thick, and riding atop a great layer of gooey molten rock called the mantle.
We have a thin-crust planet, as thin as a peel on an apple, relatively speaking. All the other planets like ours have thicker surfaces, so thick that they don't move about and buckle and crack like ours does in a little process we like to call "plate tectonics."
How did we get short crusted?
Rising in the eastern skies this evening is the answer to this long hidden mystery. In that big ball we call the Moon lies most of our old crust. Here's the latest on how this all may have worked out:
About 4.4 billion years ago our toddler solar system was congested with probably a couple dozen newly formed planets. Infant Earth was moonless then --- for a time anyway.
Back then Earth was a wee smaller and composed of a thick crust layer more typical of the other planets. And our early atmosphere was probably much thicker, too, and absolutely not right for life.
Then it happened.
One day a baby planet about twice the size of Mars collided with the Earth. Striking neither head-on nor at a glance, but somewhere in between, this impact changed the course of Earth history.
In The Impact both of our relatively thick, light crusts were sheared away and thrown scattered into orbit around a devastated Earth. The guts of the other body became one with our planet. This trauma took less than 24 hours!
But what came next was a beautiful thing to behold.
Because the collidor's guts were absorbed into the New Earth, there was now more red-hot radioactive stuff, like uranium and thorium, below the surface. Hot molten material rises, and when it does forces the crustal plates above it all to move and split and cram into each other driving plate tectonics for eons --- if the crust is thin enough.
But the impact thinned out the crust of New Earth; as a result it could be easily moved about. Now, via tectonics, there could be land and oceans, mountains and valleys, rivers and streams. And tectonics' recycling of minerals made fertile lands all over the planet.
Moreover, the atmosphere of New Earth, which was eventually reestablished, was much thinner and now conducive to life, which would be appearing soon.
And, of course, we got a new Moon out of the whole shebang. This heaven-sent heavenly body is not merely a garbage collector of tossed-up crust, oh no! The crusty Moon stabilizes our orbit, keeps us from wobbling over, and its pull on us has slowed our spin down to a comfortable 24-hour day. It also provides the ebb and flow of tides that allow a whole menagerie of life along all coasts.
If the colliding body had arrived just hours earlier or later none of this would have happened. We would still have a thick immovable crust, a heavy, sterile atmosphere, and no stabilizing Moon.
Bottom line? If this Collision hadn't occurred exactly when and where and how it did, we wouldn't be here!
A lesson here for us? Immeasurable good can rise from the flames of events that seem utterly and hopelessly devastating at the time.
Until next time, clear skies!
Posted by Administrator at 2001.09.29 08:10 AM | Comments (0)
