Virginia Urban, age 10, of Staten Island, New York, for her question:

How much hydrogen does a star consume every day?

Stars burn at different rates and the hottest ones consume their hydrogen fuel faster than cooler ones. Our sun is an average type star in almost all respects. It also is conveniently close enough for scientists to study. They have calculated the average rate at which it consumes its hydrogen fuel. And we can take this as a fairly accurate estimate of hydrogen consumption in an average star.

The basic rate is computed for an average second. During this brief moment, it is estimated that 564 million tons of hydrogen fuel are fed to the sun's nuclear fur¬nace. This fuel produces 560 million tons of helium and the process of nuclear fusion converts four million tons of the material into radiant solar energy. This means that the sun consumes 564 million tons of its hydrogen every second    which amounts to more than two hundred billion tons during an average hour.