Patti Landwehr, age 9, of St. Paul, Minn., for her question:

How do they make helium?

Helium is a gas. Like the gases of the air we cannot see it or feel it or smeil it. The sun creates billions of tons of helium gas every day, but, of course, that helium is far out of our reach. The earth created a few pockets of helium ages ago and hid them in the ground. This gas collects in our buried oil fields, and helium is mixed with other gases. We get natural gas for our kitchens from this buried mixture, and sometimes we can separate the helium from the other gases.

Helium is lighter than the air. It lifts a balloon above the ground and takes it floating aloft in the air. Helium is the very best gas for filling blimps, big balloons and dirigibles. This is because it cannot catch fire and burn a high flying aircraft.