Clash of the Titans

Abell 754 seen in X-rays
This XMM-Newton image reveals the X-ray brightness of the intergalactic gas in Abell 754. Core gas from the larger of the two clusters appears as the white and red area at the left. The regions with the highest density of matter are the brightest regions.
Courtesy ESA / XMM-Newton / J. Patrick Henry, et al.