The Joy of Gravitational Lensing, or Why You Are Seeing Five Lights…

These five lights are all the same object - a quasar. The middle one is the image we would normally see. The ones on the sides are four extra images that we can only see because there is a galaxy between us and the star. How does something getting between us and the star help us see more of it? We'll tell you the… » 11/15/12 6:20am 11/15/12 6:20am