X-ray image showing a comet-like blob of gas about 5 million light-years long hurling through a distant galaxy cluster over 500 miles per second. The comet is confined to the orange regions in this image. The head is the lower right, with reddish areas. The tail fans outward because there is less pressure to confine it. The color red refers to regions of lower entropy. The orange regions have higher entropy. Credit: ESA/XMM-Newton/Finoguenov et al.
