The Internet Archive discovers and captures web pages through many different web crawls.
At any given time several distinct crawls are running, some for months, and some every day or longer.
View the web archive through the Wayback Machine.
This graph shows the incoming solar radiation over the last 600,000 years for
summer at 65 degrees north latitude. Note the complex changes that occur in the
curve. The curve was derived using the changing values of the eccentricity of
the orbit, tilt of the axis and precession of the equinoxes. The data are from
Berger and Loutre