From the home page:

Xplanet is similar to Xearth, where an image of the earth is rendered
into an X window.  Xplanet can display several different map
projections, including Azimuthal, Mercator, Mollweide, orthographic,
or rectangular, as well as a window with a globe the user can rotate
interactively.  The other planets and some satellites may also be
displayed.  The latest version can always be found at
http://xplanet.sourceforge.net.