A long time ago in a galaxy far, far away, the average density of stars is 17 stars per cubic parsec (a cubic parsec is a cube with side 1 parsec, which is roughly 3 x 10^16 meters). In the particular cubic parsec selected around a little green planet, one finds exactly 23 stars. What is the probability that out of these 23 stars, there are exactly 4 starts in the cube with side 1/2 parsec around our little green planet?