Xmars is an X11 backdrop-generator similar to Xearth, but (obviously) designed to work for Mars, not Earth! It is a somewhat crude hack, I'm sorry to say. The orbital constants for Mars have (where possible) been obtained from reliable sources, but some have had to be estimated by hand. I make Xmars available hoping that maybe someone with better access to astrophysical constants will take it on board and fix it up to work more accurately. The images xmars generates are (or should be) what you'd see if you were in orbit around Mars, not looking at it from Earth with a telescope and seeing things 10 to 20 minutes after they happen.
