Darelena Keller, age 11, of Linden,Pa., for her question:

HOW HOT IS THE CENTER OF THE SUN?

Scientists have instruments to take an accurate reading of the sun's surface,    but none to take the temperature of its deep interior. The surface temperature is about 10,000 degrees Fahrenheit  which is more than three times as hot as    a blast furnace. Obviously it must be hot enough to trigger the nuclear activity that goes on at the center.

A great deal has been learned about nuclear fusion from experiments here on earth. The sun contains about 99.8% of all the material in the solar system, and its mass is 333,000 times greater than the earth's.  Mass and nuclear fusion are two of the factors used to figure the sun's internal temperature. Most experts agree that it must be around 27 million degrees Fahrenheit.