John Bucseh, age 9, of New Brunswick, New Jersey, for his question:

How come Jupiter has so many gases around it?

All the planets we know about are solid round balls, wrapped inside huge shells of gases. The surface of the solid earth has patches of dry land and wide oceans. Its outer shell of gases.is the airy atmosphere that reaches hundreds of miles above our heads. Jupiter is a giant with a gigantic shell of gases. Its atmosphere is very thick and cloudy    and it reaches way, way up above the surface.

Right now, giant Jupiter is in the science news. Not long ago, radio telescopes discovered some surprising new things about it. So a team of experts got ready to test this new evidence in May of this year. When the facts are sorted and computed, we can expect to hear the results. And we may be told that Jupiter is not what we thought it was. Some experts suspect that the mysterious giant may not be a planet at all. It just might be a worn out old star that perhaps joined our solar system ages ago.

However, in many ways it is very much like a planet, even though the giant is bigger than a ball made from all the other eight planets put together. Like the other planets, it has a round globe inside a shell of gases. Our moon has no gaseous atmosphere and neither do most of the moons that belong to other planets. But all the planets do    and so does the sun. Since this seems to be the rule, there must be a reason for it.

You may wonder why the earths airy gases do not leave us and drift away into outer space. Astronomers tell us that they cannot escape because of the earth's gravity. As you know, this mighty force hugs us down to the face of the earth. It pulls down falling bodies and makes heavy stones sink through lightweight water. This same force of gravity reaches up above the earth out into space. 'True, it grows weaker as it gets farther from the center of our globe. But it is strong enough to hug down our atmosphere and stop its gases from drifting away. The gravity of our moon is too weak to hold an outer shell of gases.

The larger planets have enough gravity to hold onto their gaseous atmospheres. The gravity of the starry sun keeps a huge atmosphere of blazing gases around it. Jupiter may be a planet or a weary old star of some kind. But in any case it too has gravity and this force holds down its shell of gases. The earth's gravity depends on its mass or weight. It is the invisible force that gives weight to objects on its surface. Jupiter's mass is about 318 times greater than ours    so its gravity is much stronger. If you weigh 100 pounds on earth, on Jupiter you would weigh 264 pounds. All this extra pulling power works to hold down that enormous atmosphere. No wonder giant Jupiter has more than its share of cloudy gases.

Astronomers planned to test Jupiter's gases this year, when they could measure them by a passing star. Most experts thought they were mostly methane and ammonia, like the gases around the other large outer planets. But some now suspect that they may be helium and hydrogen. If this turns out to be so, Jupiter just may be a dying star instead of a fairly young planet.