Brian Grainger, age 11, of Toronto, Ontario, Canada, for his question:

Is life on other planets impossible?

Our planet, of course, is surrounded by oceans of space and merely crossing to our little neighboring moon is an immense project. We know that the moon is uninhabited and this tends to make earthlings feel very lonely and islolated in the cosmic picture. So we wonder about the possibility of life on other worlds and perhaps hope that someday we may introduce ourselves to intelligent alien beings.

Think of a number, large or small, and ask someone to read your mind. If your friend sifts through enough numbers, large and small, sooner or later he is certain to find the right one. The cosmos is infinite and we just do not have enough numbers, large or small, to cope with its countless possibilities. There are merely nine planets in our Solar System. We have investigated one of them and found it to be teeming with assorted forms of life. So far we have not investigated to learn whether or not there is life on the sun's.: other eight planets.

Lately, astronomers have identified planetary systems in the heavens, and scientists have come to the conclusion that solar systems are not rare. It is possible, and even likely, that most of the 100 billion stars in our galaxy have their families of orbiting planets. The number of possible planets grows enormous and so does the likelihood that some of them enjoy the earth type conditions needed to support earth type life. Now add the billions of other galaxies strewn through the cosmos    and their zillions of planets. Certainly some of them are earth type planets. And from plenteous experience here on earth, we know that life tends to spring up when and wherever conditions are suitable.

So, when we multiply the number of planets almost to infinity, we can be quite certain that life does indeed exist on other planets. It may or may not be earth type life, depending upon different conditions    air and minerals, light and warmth. But somewhere Out There, you can bet your boots that life exists. A few rare planets most likely have intelligent life forms, capable of conversing with the trustees of the planet Earth. Someday, who knows, we may meet them. And naturally we want to make the best possible impression.

When we view the scope of human history in a big way, we stress the stupendous achievements made in a few thousand years. We observe how mankind always sheds his worst attributes and advances to higher levels of civilization. When at last we  overcome warfare and other natural belligerencies we shall want to share our inner rewards of happy contentment. Like civilized individuals of today, man's history pleasure will be lending a friendly hand to help those behind him. Then mankind will be ready to go star trekking    and sooner or later he will find life on other worlds. And sooner or later he will find a rare planet inhabited by intelligent beings    but to be ready for this encounter he must be truly civilized.

The lunar landing is the greatest of all events inhuman history. But the moon is a mere step in the vast cosmos and human history is merely a blink in cosmic time. Mars, Venus and our planet brethren are mere specks in the vast, teeming cosmos. They may or may not support simple forms of life, but in. our Solar System only our planet has the luxurious conditions necessary for earth type life. However, among zillions of planets there must be many more that support earth type or non earth type life    and some of them must be inhabited by beings, as smart or smarter than we are.