Claire Shelmire, age 8, of Dallas, Texas, for her question:

How big is the biggest star?

Our astronomers have measured thousands of stars. But there are billions of stars that they have never even counted, let alone measured. They cannot tell us which is the biggest star in the whole heavens. But they can tell us which is the biggest star they have found and measured. Its fine sounding name is Epsilon Aurigae and this star is a whopper. Our starry sun is big enough to swallow our whole world a million times and still have lots of room for dessert. A line straight through the middle of the sun from side to side is about 860,000 miles long, This is its diameter and it equals two trips from the earth to the moon and back.

The diameter of Epsilon Aurigae is 2,000 times greater than the diameter of the sun. If this giant star replaced our sun, it would reach far out beyond the earth's orbit and our world would be inside it. It is not a brilliant star in our sky because it is very far away. It appears in the fall and even when you know just where to look, the supergiant is too dim to be seen, unless your eyes are very, very sharp.