Xearth is a definite blast from the past, and it shows; the program's origins date back more than 20 years, and not a lot has changed since then. But Xearth still functions as a really cool desktop background that shows the Earth's rotation in real time. There are probably similar programs that are much more sophisticated, but if you want to kick it old-school, Xearth is a fun and interesting choice.
Upon installation, the program filled our desktop with a spherical view of the Earth against a starry black background. The default view showed the part of the world that was currently receiving daylight, which updates automatically every 5 minutes, but there are plenty of options for adjusting what Xearth displays.
We were frustrated that we were never able to view our current location on the map; we entered our city's latitude and longitude, but Xearth kept displaying the other side of the planet. In general we found ourselves wishing for a Help file, as the various options menus were less than intuitive, and they will likely frustrate users who aren't familiar with this kind of software. We did think it was cool that Xearth displays yellow circles representing recent earthquake activity, and overall we felt that Xearth was an attractive addition to our desktop. It could be really fun and useful with a bit of documentation and some updated menus.
Xearth comes as a ZIP file and is accessible after extraction with no need for installation.