Good find. If you zoom in as far as you can on a planet, then try to zoom in again, it will add a selectable point that's fixed to the surface.
This was an experiment in letting the user "land" on the planet to see what the sky looks like from that point. More to do on this to complete the feature.
If you add a number of points on the "Earth", turn up trail length, and hit "B" to hide bodies, you can get some pretty cool looking trails.