I am a retired meteorologist - just an interest in astronomy. The last
ice age ended about 20k years ago. Nobody really knows why ice ages
happen but I have often wondered about interstellar dust. Seems
reasonable to me that as the solar system rotates around the galaxy it
may encounter dust clouds which would reduce solar radiation reaching
the Earth and thus trigger ice ages. There are some suggestions that
the sun is a variable star. How would it be shown if this could just
be due to interstellar dust? Would this dust actually be between the
Earth and the Sun or would the solar 'wind' keep it away?