-Draws a planet bouncing around in space. Written by David Konerding.
-The built-in image is a map of the earth (extracted from `xearth'),
-but you can wrap any texture around the sphere, e.g., the planetary
-textures that come with `ssystem'.
+The Earth, bouncing around in space, rendered with satellite imagery
+of the planet in both sunlight and darkness.
+
+If you would like it to display a different planet, any pair of
+Equirectangular-projected maps will work. The maps that come with
+"ssystem" work well.
+
+Written by David Konerding and Jamie Zawinski; 1998.