Gayle Pasco, age 10, of Niagara Falls, Ontario, Canada, for her question:

Is it true that planets formed from dust?

The planets are huge worlds and four of those in our Solar System are much bigger than our earth. All of them are billions of years old and full of secrets. Compared with them, people are very small and very young. People are also somewhat fond of easy answers. We may say that the gigantic old planets were formed from dust. But if they were, it must have been some most remarkable dust and the building job must have been super stupendous.

Every young space ager wonders how and when the Solar System was born. It would be nice if some world famous scientists would explain the great event     in definite, positive detail. But this does not happen. Instead, we are told that the planets may have been ford in this way or that way     or in~some other way at some other time. This sort of talk is frustrating, to say the least, and tends to dive a curious young student to distraction.

Now is the time to maintain a cool head, count to ten and pause to re organize your thinking equipment. Remind yourself that this is a science type question. And, it is common knowledge that when a scientist knows that he really knows the answer, he is delighted to explain the whole thing down to the finest detail. In fact, listeners often think that he goes on too long. However, that same scientist will refuse to give any sort of definite yes or no     unless he can prove his answer is true. At least, that is how a reliable scientist behaves.

The scientists interested in the planets and Solar System are, as we know, astron¬omers. Naturally they study for years, observing and gathering new evidence, mastering special skills and testing to prove which evidence is true or false. This groundwork makes them experts. When they tell us, Yes this is so, we can trust them.

But, sad to say, most of our burning questions have no definite answers     as yet. For example, we may be told that perhaps the planets were formed from dusty debris. Astronomers have gathered enough evidence to suggest a theory about the origin of the Solar System. But a theory is merely an educated guess. There is a lot of evidence to back it up. But more definite facts must be known before we can prove it true or false.

Astronomers have a favorite theory about how the planets were made. If this proves to be true, all the material in the Solar System was once an enormous cloud of dusty gases. Most of this material gathered in the center to form the sun. But some was left twirling around the sun in circles. If this theory is true, then the planets were formed from those whirls of dusty gases.

Proving this theory is very difficult because the birth of the Solar System goes back some five billion years. Some of the evidence was gathered from the earth. Some was observed on other planets from afar. Astronauts brought more evidence from the moon. But some experts think we may have to wait until space probes and maybe astro¬nauts set down on other planets. Possibly they may return with positive proof of how the planets of our Solar System were formed.