Once in a 'blue moon' on Tuesday...but there's a catch Summary: On Tuesday night you can see a relatively rare event - a blue moon. But there's a good chance you'll be disappointed. By Andy Smith | August 20, 2013 -- 20:18 GMT (13:18 PDT) Previous | Next Image 6 of 6 Another Saturn moon, called Mimas or the Death Star moon shows a bluish band near the equator of the icy moon. Topic: Nasa / Space Kick off your day with ZDNet's daily email newsletter. It's the freshest tech news and opinion, served hot. Get it.