Lloyd Goodwin, age 9, of Berea, Ohio, for his question:

Which is the coldest Planet?

It seems that planets and other things can get dust so cold, but no colder. The limit is minus 459.67 degrees Fahrenheit and scientists call it "absolute zero". This shuddering temperature is 491 degrees colder than freezing water. And nothing can get any colder than absolute zero. Planets of course are warmed by the sun. But Jupiter and Saturn, Uranus and Neptune and Pluto are too far away to get any warmth worth mentioning. Scientists used to think that all these outer planets were almost as cold a possible, perhaps a few degrees above absolute zero.

Then came the space age, bringing masses of new information about the whole Solar System. Some of our older ideas were wrong and had to be changed. For example, Jupiter is warmer than expected. At present, nobody knows the exact tem¬perature of all the planets. We must wait for a lot more information before we can say exactly how cold each one is.