Like piecing together a car accident, by looking at the results of a collision in space, we can use our knowledge of science to piece together the past and determine what happened to a high degree of accuracy.  The velocity of a star, along with high powered computer simulations and statistical techniques, can help us determine where it once was.  But since space is so vast, why do we care where stars have moved? The short answer is that there are so many stars out there that we don’t often care where individual stars have moved.  Some exceptions are when...