Donna Bass, age 8, of East Brunswick, N.J., for her question:
WHAT EXACTLY IS A STAR?
Stars have always fascinated man. In ancient times, people made up stories about figures they saw in certain clusters of stars called constellations. Many farmers watched the stars to find out when to plant their crops, and early day travelers determined directions by following the courses marked by stars in the sky.
A star is nothing more than a huge ball of glowing gas in the sky. And there are lots of them up there in space.
Our sun is a star, and it is close enough to the earth to look like a ball. All the other stars are so far away that they appear to us only as pinpoints of light, if they can be seen at all.
Are you ready for a really big number? Look at this: 200,000,000,000,000,000,000. The number is 200 billion billion, and that's the number of stars that are glowing up there in our universe.
About 75 percent of a star is made of hydrogen, with 22 percent helium. Then there are traces of oxygen, neon, carbon and nitrogen. Inside a star reaches more than 2 million degrees Fahrenheit, and on the outside it can range from 5,000 degrees to 50,000 degrees.
The smallest star is smaller than the earth, but the largest is about 1 billion miles in diameter. That's about 1,000 times larger than our sun, and it would actually fill a space as wide as it is between our earth and the sun.
It is really hard to imagine the distances between stars and their numbers.
Stars shine because atomic energy makes their gases very hot. They continue to shine until they run out of hydrogen gas, the fuel used to make the atomic energy. When the fuel is gone, a star will usually explode into a huge cloud of gas and dust.
New stars are still forming within the clouds of gas and dust left over from old stars. Our sun was probably formed this way. Scientists also say that the earth took shape from the same material as the sun. The earth and all lving things on it were probably made up of atoms that once were part of a star.
Stars appear to twinkle when we see them because the light comes to us through moving layers of air that surround the earth.
On a clear night you're able to see about 2,000 stars. Another 2,000 can be seen from the opposite side of the world. With a three inch telescope a total of 600,000 can be seen. With our largest telescopes we can see about 3 billion individual stars and more than 1 billion galaxies. Only a few stars have been given names.