Dale Sabin, age 12, of Esko, Minn., for his question:

WHERE DO WE GET HELIUM?

Helium is a lightweight gas and chemical element. It is called an inert gas, or noble gas, because it does not combine with other elements.

On earth, helium can be found in natural gas deposits and in the atmosphere. The atmosphere contains about five parts of helium per million parts of air. It makes up only a small fraction of the earth's matter but is one of the most common elements in the universe. The sun and other stars are made mostly of helium and hydrogen.

Largest industrial use of helium is in a type of electric arc welding. It is also used to fill scientific balloons. The government's chief use of helium is in maintaining proper pressures in rockets. Helium produces pressure which forces fuel into rocket pumping systems.