Christine Zdeb, age 12, of St. Catharines, Ontario, Canada, for her question:
Is it true that the moon came out of the Pacific Ocean?
Our lunar probes axe bringing us close up news from the moon. Many of the facts they report are new and surprising. Scientists are using this data to reevaluate old theories and opinions. But they still are unable to give us a positive picture of the moon or a positive account of its origin.
Some people seem to think that scientists are completely certain the moon was torn ales ago from the basin of the Pacific Ocean. These people are mistaken. If they learned this as a positive fact, then they were listening to a non-scientist or reading an account by a sloppy reporter. We have all wondered about the birth of the moon and astronomers, you may be sure, are mighty curious about it. But scientists are very fussy people when it comes to facts. They refuse to state that something is true unless they can prove the facts and make more tests to prove them again and again. `
At the moment, nobody on earth knows enough facts to prove how the moon was born. And no scientist will state that he has the answer. In the meantime, this does not stop a good scientist from using the facts that he does have to make an educated guess. This guess is called a theory. An expert who expresses a theory must set forth a lot of facts to back it up. But he knows that a theory is not a statement of fact and he assumes that everyone else knows this too. Later, the theory may be proved true or false.
Scientists have made several educated guesses about the birth of the moon. One theory suggested that in ages past a great gob of material was torn from the body of our planet. It was suggested that this upset could have occurred when the young earth was less solid, perhaps in a plastic or even gaseous state. The theory went on to suggest, merely to suggest, that such a gob of material may have swung away and eventually became our solid, orbiting moon. The hole left by this suggested upheaval might, just might, have been the basin of the Pacific.
The experts who set forth this theory had some, but not much factual evidence to back it up. Now, growing evidence about the origin of the entire Solar System has given rise to other theories about the birth of the moon. These suggest that the moon was never part of the earth. It formed as the earth formed, from the mass of cosmic fragments used to create the entire Solar System. Many experts suspect that the same cosmic forces welded these fragments into larger and smaller bodies. Perhaps one of the massive bodies became the planet earth. A smaller body in the neighborhood might have been captured by the earth's gravity and the captive may have become the moon.
Until lunar spacecraft sent back photographs of the far side of the moon, nobody could say what it looked like. Until the probes sent back other data, many scientists suspected that the lunar landscape might be waist deep in powdery cinders. The lunar investigation has just begun and, as yet, nobody has enough facts to state positively how it was born. Even with more and still more facts, scientists may have only theories. We may never learn whether the moon truly did or did not come out of the Pacific Ocean.