The stars in this shot are in their actual real-world positions (I think for the equator at 0 degrees longitude in 1900) and are rendered using 6000 point sprites. They are also given a size based on their brightness in the yale catalog. I think that it's pretty cool that you'll be able to look up at the sky in PBS and pick out constellations, even being able to tell which direction is which based on their relative positions.