Sunspeed didactical toy
on the following way:
every single circle forms
angle of 2.5° with the pin in respect to previous
circle. The Earth’s rotation
advances this 2.5° in
10 minutes causing shadow to pass every next
circle precisely in 10
minute intervals.
It is 3D: click it with
mice to rotate and
roll the middle button
to zoom, press it to
move around.