Open Cluster M103: This beautiful open cluster is with approx. 7000 LY distance the one with the longest distance to us of all the Messier star clusters. It´s extent is 17 LY.

The brightest star at the top of the cluster shines blue (spectral class B5) with 40000 times the brightness of our sun. As can be seen it represents a triple system. The second brightest star in the center is a red giant of spectral class M1, 10000 times brighter than our sun. The bright star at the left corner does not belong to the cluster, it´s a foreground star.