airs with the help of a telescope. I don't think there's an amateur astronomer I know who doesn't enjoy observing double stars. It's fun, easy, rewarding, doesn't take a complicated setup, you can observe from within a city, and challenging objects exist for every size of telescope.<br><br>In addition to where the double star is in the sky and how bright each component is, there are two quantities with which a double star observer should be familiar. The first is the "separation" of the pair. This number is