Temperature of Mercury and Comets
Country: United Kingdom
Date: Spring 2014
Is it true that the planet Mercury is very hot but the side not facing the sun is very cold? If that is true why does the heat from the sun not surround the planet and do comets that come close to the sun? If some comets have been passing by us for hundreds if not thousands or even millions of years why have they not burned out?
You have a lot of good questions here! One at a time...
Yes. Mercury's cold side is VERY cold because there is no atmosphere to transfer heat from one side to the other.
Comet have the same problem, and heat up very quickly when sunlight strikes them. The movie Deep Impact was correct on that point.
Some comets indeed have died off after many passes near the Sun!
David H. Levy
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Update: December 2011