It also explains why some people have regular cut outs at certain times of the day. Sirius 1 may dip below the horizon before number 2 can peak out from behind your neighbors house. I guess it goes back to the XM is better for staionary while Sirius is better for mobile argument.

In any case, I'm going to watch that pic for a few more hours

 

I think XM's birds are higher (22,241 statute miles) becuase they have a geosynchronous orbit.