It’s rare for galaxy clusters to collide and merge at high speeds. An iconic example is the Bullet Cluster, the aftermath of two vast galaxy clusters that collided. To be able to “replay” what happened, and in which order, researchers need to first fully define all the contents in this scene.

NASA’s James Webb Space Telescope has provided some of the best information to date: Highly precise, extremely detailed near-infrared images of a significant portion of the Bullet Cluster. Its new observations allowed researchers to fine tune their maps of its mass, including an invisible substance known as dark matter that does not emit, reflect, or absorb light.