In the upper right is a ground-based image of Caldwell 76 (NGC 6231) from the Digitized Sky Survey (DSS), showing a cluster of many stars. In the left is a Hubble closeup of some of its stars, which are variously bright and blue-white and red.

NGC 6231 With Inset

In the upper right is a ground-based image of Caldwell 76 (NGC 6231) from the Digitized Sky Survey (DSS). An outline shows the part of the cluster observed by Hubble’s Wide Field and Planetary Camera 2 (WFPC2).

Credits: Ground-based image: Digitized Sky Survey; Hubble image: NASA, ESA, and J. Maiz Apellaniz (Centro de Astrobiologia [CSIC/INTA]); Processing: Gladys Kober (NASA/Catholic University of America)