We continued last week's project with Gwendolyn by completing the glittering of the stars of the Big Dipper. We also glued the photo of the constellation onto black paper in preparation of completing the mobile, and added the names of the stars. Since this is a scaled-down model (obviously) we need to convert the real distance in lightyears to something more manageable such as centimeters or inches. I explained to Gwendolyn that since distances in space are so vast, it is convenient to express these distances as lightyears, i.e. the distance light travels in one year. We calculated this together from a starting point of 186,000 miles per second, and ended up with a very large number indeed. The stars in the Big Dipper lie between some 78 to 123 or so lightyears away. Gwendolyn is very fast with mental arithmetic, it was fun to do this exercise with her!