Jim Solay, age 15, of Gary, Indiana, for his question:

What makes a meteor burn up in the atmosphere?

Almost anything will catch on fire if it becomes hot enough. And one way to generate heat is by friction. If you rub your finger back and forth fast over a smooth surface, the skin becomes warm. This heat v!!as generated by friction. The same thing, on a more dramatic scale, happens when you strike a match. The friction from rubbing on the emery board generates enough heat to ignite the chemicals in the match head. A meteor striking into the earths atmosphere generates the same kind of frictional heat   only with more intensity.

The meteors which strike the earth are solid fragments, most of them no bigger than pinheads. Small as they are, these tiny space travelers generate enough fuss to be seen as so called shooting stars. It is estimated that about 24 million of them enter our atmosphere every 24 hours plus millions and perhaps billions of still smaller ones.

There are certainly a great many meteors, big and small, traveling the spaceways. At one time it was thought that some of them came from beyond the Solar  Systerd. But the radio telescope has proved that all of them are members  of the Solar Family. In countless numbers they roam the spaceways between the planets, and my, what space travelers they are. They whizz  along at speeds from five to twenty miles a second.

Compared with other travelers of the Solar System, however, this is no drag race. Our staid old earth bowls around its orbit at an average speed of 181 miles a second and the entire Solar System swings around the galaxy at 170 miles a second. We do not notice speed, however, when we are in full swing. It makes itself felt when we stop or slow up.

Nothing happens to the little pinhead meteor through its ages of speedy travel through empty space.

Then comes the traffic accident. It collides with the massive earth   a planet so big that it does not even notice the fall of one pinhead. What’s more, it is protected with a blanket of atmosphere reaching hundreds of miles above the surface. The molecules of air get in the way of the speeding space traveler, slow it up and force it to put on the brakes. It is estimated that a meteor knocks off perhaps 30,000 electrons froth air molecules during every foot of its descent. This kind of frictional activity generates heat.

At about 60 miles above the ground, the little meteor is so hot that it becomes incandescent. We see it as a shooting star. Meantime –in solid material is converted to gases and ashes. At about 40 miles above the ground its light goes out because it is entirely consumed. The ashes from one little meteor sifting down to the ground is not noticeable. But all the falling meteors add several pounds to the earth. Through the years, the earth is adding many tons of meteor dust to her weight.