Chandra Release - January 2, 2004

Visual Description: RDCS 1252.9-2927

This is an X-ray and optical image of a distant galaxy cluster known as RDCS 1252.9-2927. It appears to be made up of many different colored dots all over the image and with a large irregular purple splotch over most of it.  The X-ray light is colored in purple, and shows the 70-million-degree Celsius gas in the cluster. The optical (in the red, yellow, blue and green) light shows the galaxies and sources in the field of view. X-ray data from Chandra and the XMM-Newton Observatory (the latter is not pictured) show that this cluster was fully formed more than 8 billion years ago, and has a mass at least 200 trillion times that of the Sun. At a distance of 8.5 billion light years, it is the most massive cluster ever observed at such an early stage in the evolution of the universe at the time of observation.