 


198K 

This movie shows a circle on a sphere projected stereographically onto the
plane from a point at the north pole of the sphere. The circle is
initially at the south pole, then grows to the equator, and then shrinks
toward the south pole. The light rays are shown to help you see the
projection. Once the circle reaches the top, the light rays are removed
and the circle moves again to the south pole.




107K 

This movie shows a another squence of circles projected from the
sphere. This time, the circles enlarge until one of them passes through
the light source. The image of this circle is a straight line in the
plane. All the other images are circles in the plane, though some are so
large that you can't see them entirely in the picture.




111K 

This movie shows a small circle that starts at the bottom of the
sphere and them travels up the side and over the top of the sphere.




129K 

This movie shows circles on the sphere that all go through the south
pole. They grow larger until they pass over the north pole and return
again to the bottom. Note that as the circle passes over the top, the
image becomes a straight line; the image goes from being a circle on one
side of this line to a circle on the other side.




128K 

This movie shows circles on the sphere that all go through the north
pole. They grow larger until they pass under the south pole and return
again to the top. Note that the image of every such circle is a straight
line.
