Xearth for Macintosh is a port of the UNIX program Xearth by Kirk
Johnson. It displays a rendered image of the Earth in a window which
can update in real time.

The application is on a Disk Copy 4.2 disk image (1.44MB) inside a
StuffIt 3.5 archive.

Compatibility
Architecture: 68k PPC

The ReadMe says a 68K version was going to be ported "in a short
while", but may or may not ever have been done.