Clyde Walker, aged 10, of Baskerville, Va., for his question:
Is an thing hotter than the sun?
Can you imagine anything sixty times as hot as a mettle of boiling water? If so, you can begin to imagine the temperature of the sun, Water boils at 100 degrees Centigrade. The surface of the sun, we are told, has a temperature of about 6,000 degrees Centigrade.
But this is only the cool, outer shell of the sun. Things get hotter as we imagine ourselves further inside. The seething interior of the sun is estimated to be at least twenty million degrees Centigrade. It is surely impossible for us to imagine such a temperature. Yet the experts say that temperatures exist which are far hotter than our seething sun.
Naturally we shall look for them in the stars. For these heavenly bodies are the hot atomic powerhouses of the universe. As a star, our sun rates as medium in all respects. It is neither the largest nor the smallest. It is neither the hottest nor the coolest.
As stars go, it seems that the really hot ones are generally the small ones. These are the white dwarf stars, some of them no larger than planets. The surface temperatures of some of these stars have been estimated at 30,000 degrees Centigrade. This is five times hotter than the surface of our sun. These stars glow white hot, rather than yellow hot like our sun.
The white dwarf stars are far too small to be seen without a telescope. But there are plenty of stars hotter than the sun which can be clearly seen in the sky. Find the brilliant constellation Orion on a winter's night. At Orion's foot is the bright star Rigel.
The light from Rigel set out to shine on you 540 years ago. For Rigal is some 540 light years from our earth. Its surface temperature is estimated to be over 12,000 degrees Centigrade. It is a bluish white star, at least twice as hot as our golden sun.
Almost as hot as Rigel is bright Sirius of the Big Dog constellation. Sirius is estimated to have a surface temperature of about 11,000 degrees Centigrade. It is one of the nearest stars to our sun. Its light set out to reach us dust over eight and one half years ago.
When it comes to hot stars, the Little Dog constellation also has one in the running. Its brightest star is Procyon with a surface temperature of 7,000 degrees Centigrade. Procyon is much cooler than dazzling Sirius. It Is also almost twice as far away from us.