This entropy map separates the cold and dense gas of the comet from the hotter and more rarefied gas of the cluster. The data shows the process of gas being stripped from the comet's core (entropy goes up) and forming a large tail containing lumps of colder and denser gas. The researchers estimate that a sun's worth of mass is lost every hour. Credit: ESA/XMM-Newton/Finoguenov et al.
