Susanne Scheid, age 9, of Pittsburgh, Pa., for her question:
What are the real colors of the stars?
On a c1ear night the sky is dotted with dozens of golden stars but if you look at them one by one, you will notice different colors. Most of them are golden yellow. But with sharp eyes you may find an orange star, a red one and perhaps one like a glittery white diamond.
Our eyes can see stars of different colors, such as golden yellow, orange and red. An astronomer uses a telescope to look at the stars. The telescope makes the stars look bigger and brighter and if its magnifying lenses are strong enough, it shows up their colors. It shows that some stars are blue and some are green. Some are burning orange and some are glowing red. Some are white and some are bluish white.
The light from a blazing fire of logs is mostly golden yellow and red. We can buy crystals to throw on the logs and make them more colorful. The crystals are different chemicals. When they burn, they shoot off flames and sparks of green and blue and silvery white. This is because different chemicals burn with different colors. A chemist can tell which color comes from each of the burning chemicals.
A star is an atomic bonfire of blazing chemicals. Its color can tell an astronomer a lot about it. He can name its most plentiful chemicals and also can tell how hot it must be to make these chemicals burn. You might think that the hottest stars are the red ones and that perhaps the next hottest ones are reddish orange but this is not so.
The hottest stars are blue white. Some of them are very small and made of very heavy materials. They may be twice as hot as the white stars. Some white stars are far more brilliant than our sun and often twice as hot. Yellow white stars are a lot cooler than the whites but they are hotter than our sun. Like most of the stars in the sky, our sun is a yellow medium star, medium hot and medium bright.
Orange stars are cooler than the sun and much bigger. The coolest stars are huge red giants, often thousands of times bigger than the sun. A red giant may be 12 times cooler than a little blue white star and half as cool as the sun. True, it is a red hot star, but white stars are white hot and a white hot furpace is much hotter than a red hot furnace.
Astronomers say that the sun's outer skin is 6,000 degrees centigrade. This is 60 times hotter than boiling water and boiling water is hot enough to cook potatoes. On the surface of our yellow star, a potato would turn to gases in a moment. A blue white star may be hundreds of times hotter than boiling water and boiling water would seem cold, even on one of the cool, red giant stars.