The sun's influence on earth
Besides the fact that the sun heats up the Earth, there are a few other clear influences.
As we saw on the photosphere-page, the number
of solar spots isn't constant in time. In fact, between 1640 and 1700 there were
virtually no sunspots at all. That period coincides with the `little ice age': It was
much colder in that era. This might be coincidence, but it might also be
causally related. This is yet unknown.
The Skylab satellite has measured how much energy the Sun radiates in
total. That too appeared not to be constant, but variable with a few tenths of
percentage points. This can have an influence on earth's climate.
The charged particles of the solar wind are responsible for the
northern and southern polar lights, when they hit earth's atmosphere
at high speed and make it shine (a bit like a TL-light).
The picture on the left was taken from the space shuttle, and shows
the northern lights as seen from space.
This shows that the Sun has a number of influences on earth. This, however, is nothing compared to what will happen in a few billion years...
