Harry Carney, age 10, of Greenbrier, Tennessee, for his question:

 What color are the hottest stars?

It so happens that astrophysicists use the color of a star as one factor in estimating its temperature. Our sun is yellow and well known to everyone as a medium star in all respects. Its surface temperature of 11,000 degrees Fahrenheit is neither very hot nor very cool  as stars go. Other yellow stars of the same type also blaze away at about the same temperature. The whopping star Antares is red. Its gases are thin and its temperature is very cool. Other red giants and supergiants also are cool temperature stars.

The hottest stars are brilliant blue white in color. They are burning with terrific fury and their material is so densely packed that all their atoms are ionized. Some of the blue white celestial powerhouses are estimated to have temperatures approaching 100,000 degrees.