Xearth sets the X root window to an image of the Earth, as
seen from your favorite vantage point in space,  correctly
shaded  for  the  current position of the Sun. By default,
xearth updates the displayed image every five minutes. The
time between updates can be changed with the -wait option.
Xearth  can  also  render  directly into PPM and GIF files
instead of drawing in the root window.

There are four addition marker file installed in
/usr/X11R6/lib/X11/xearth which specify the locations of
various FreeBSD people and places:

freebsd.core.markers - members of the FreeBSD core team
freebsd.committers.markers - FreeBSD committers (non-core)
freebsd.core_and_committers.markers - core plus committers
freebsd.ftp.markers - FreeBSD FTP mirrors

WWW: http://www.cs.colorado.edu/~tuna/xearth/index.html