QUESTION:
Why does the temperature change so drastically on planets like Pluto and
Neptune?  The earth in comparison has very little change!

ANSWER from Heidi Hammel on June 3, 1996:
I am not sure what "drastic" temperature changes this question refers to,
so it is somewhat hard to answer directly.  All planets have variations in
temperature, both in their atmospheres and inside the planets themselves.

Even the Earth has large ranges in temperature.  The temperatures change
across on the surface  of the Earth (think about the difference between
Death Valley in California and Antartica).  Even in one place, the
temperatures change a lot with time (consider the difference between a
sizzling hot summer day in Kansas and a frigid cold winter night in the
same town).  Finally, the Earth's temperature increases a huge amount
if you go deep into the planet (think about where lava -- molten rock --
comes from).