What it’s: The Bullet Cluster
The place it’s: 3.7 billion light-years from Earth, within the constellation Carina
When it was shared: June 30, 2025
Why it is so particular: Galaxy clusters act as a magnifying lens, shining gentle on the faintest and most distant objects — a phenomenon referred to as gravitational lensing. On the rarest of events, galaxy clusters collide, creating an much more huge lens. The James Webb Area Telescope (JWST) lately supplied extraordinarily detailed observations of such a lens, the Bullet Cluster.
Situated about 3.7 billion light-years from Earth within the constellation Carina, the Bullet Cluster is the aftermath of the collision between two galaxy clusters that’s estimated to have begun roughly 150 million years in the past. Every of the 2 galaxy clusters might be distinguished throughout the blue areas, but they’re certain by gravity and collectively type a single entity — the Bullet Cluster.
Whereas gravitational lensing brings distant, faint objects into gentle, the extent of lensing can reveal the mass distribution throughout the huge foreground galaxy cluster. Mysterious darkish matter makes up an enormous chunk of galaxy clusters, however is troublesome to identify as a result of it doesn’t replicate, soak up or emit gentle. So, astronomers typically examine gentle from stars which might be throughout the galaxy cluster however aren’t a part of any galaxies. These stars are known as intracluster stars and are floating as a result of they’re stripped from their galaxies throughout collisions. By analyzing the sunshine from these stars, researchers can hint the distribution of darkish matter, as these stars are gravitationally certain to the cluster’s darkish matter.
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The newest information from JWST, mixed with information from the Chandra X-ray Observatory, allowed astronomers to create an correct map of mass — each seen and darkish matter — throughout the Bullet Cluster. The sunshine from intracluster stars pinned down the situation of invisible matter, and the X-rays confirmed the situation of scorching gasoline. Based mostly on these observations, astronomers may “replay” the collision. This revealed that scorching gasoline (in brilliant pink) was pulled out of the galaxy clusters and left behind within the central area, whereas the darkish matter (in blue) related to particular person galaxy clusters stayed intact and was not dragged away.
This gorgeous picture, a composite of JWST’s near-infrared information and Chandra’s X-ray information, reveals clumps and stretched-out strains of mass that had been beforehand unknown. These newfound constructions might be signatures of a chaotic historical past, suggesting that the Bullet Cluster could have suffered a number of collisions over billions of years. The bigger cluster, on the left aspect, may need undergone separate interactions earlier than and after colliding with the smaller cluster on the fitting.
This sensible picture covers solely a portion of the collision’s aftermath. Sooner or later, the wide-area near-infrared photos taken with NASA’s Nancy Grace Roman Area Telescope may present an entire image of the Bullet Cluster, each by unveiling spectacular images and unraveling its mysteries.
For extra elegant area photos, try our Area Photograph of the Week archives.
