While you are enjoying your Christmas, Kwanzaa, or Chanukah, look up and think about how some of our greatest gifts are free. The Christmas Tree Cluster is composed of bright blue stars in front of a red gas background. It was first discovered in the 18th century, but was captured again from the European Southern Observatory in Chile. The cluster is in the constellation of Monoceros, the unicorn, about 2,600 light years from Earth.