three-dimension maps of our mickey way galaxy. looking at the data the astronomers see stream of stars going through and one is going the opposite direction of our spins in the mickey way. they are seeing these stra inii the colliding galaxy if you will and able to calculate the dark matter. dark matter is a theory and not conclusively detected but basically astronomers it look at these and calculate how much mass has to be there and sometimes we are seeing factors of five, ten, or a hundred times less mass than should be there. or, you know, that weshe should able to see more and how they came up with the dark matter back in the late 1800s. it sounds fascinating but what does it mean? ? it means we have stars