John P. Nowicki, age 10, of Newhartford,New York, for his question:

Why do rockets burn in the atmosphere?

If you rub a finger briskly on a table for a minute or so, it gets warm. The heat is created by friction and it happens whenever objects rub together. A rocket is certainly an object    but so is the atmosphere. Actually the air is a hodge podge of invisibly small molecules of gases. What they lack in size, they make up for in numbers. Zillions of them bash onto all sides of the descending rocket. This creates friction and the friction creates heat.

The friction begins even in the upper atmosphere, where the air molecules are few and far between. It grows more intense as the rocket descends into lower levels of atmosphere. Down here the air gets thicker and denser. So the rocket gets hotter as it gets closer to the earth. And the faster it goes, the more friction it creates and the hotter it gets. Its temperature may reach several thousand degrees    which is why it is provided with a heat shield.