NOAA
Noaa: Paleoclimatology Program: Astronomical Theory of Climate Change
Use this site to learn how the Earth's not-so-circular orbit around the sun has affected our climate over thousands of years, and continues to affect our climate now.
Cornell University
Cornell University: Astronomy: Eclipses
This site from the Astronomy Department of Cornell University provides brief introduction to both solar and lunar eclipses. Links are provided for pictures and charts of the eclipses, and this is a good site to check out on the subject.