ESA originally published this story on January 22, 2026. Edited by EarthSky.
A cluster of galaxies and its lens galaxies
Check out the beautiful picture above from The James Webb Space Telescope. It’s Webb’s Picture of the Moon. Most of the spots you see in the image are distant galaxies. In the center is the cluster itself, the so-called MACS J1149.5+2223or MACS J1149 for short. It’s the ghostly cluster of elliptical galaxies in the center of the image. These galaxies are about 5 billion light-years away in the direction of Leo the lion, and the scene is dominated by massive gravity.
Gravity pulls together hundreds of galaxies in the cluster itself. And that same gravity also bends, magnifies and distorts the light of even more distant background galaxies, creating the faint curved arcs seen in the image.
This is the phenomenon of gravitational lensing. The mass of the main galaxy cluster provides a “lens” that allows us to see the more distant galaxies beyond.
Notice the “pink jellyfish”
This phenomenon of gravitational lensing allows us to see distant galaxies that we would not otherwise be able to see. That’s what you see scattered across the MACS J1149 image: subtle and not-so-subtle examples of gravitational lensing, from galaxies that appear to be stretched into narrow bands of light to images of galaxies that have morphed into strange shapes.
You can see a fantastic example of gravitational lensing near the center of the image. Look just below the bright white galaxies at the heart of the cluster. There, the image of a galaxy with prominent spiral arms morphed into something resembling a pink jellyfish. This tangled galaxy is home to what once was the most distant single star ever discovered as well as the supernova whose image appeared four times at once.
Scroll through a spectacular cluster of galaxies in this video from ESA.
A bunch of galaxies of celebrities
MACS J1149 has long received celebrity access from leading telescopes, and for good reason. This cluster was one of six examined by the Hubble Space Telescope Boundary field program. Scientists have chosen Frontier Fields galaxy clusters for the strength of their gravitational lensing. Their ability to warp space-time has given researchers a glimpse into the early universe.
Now Webb is pushing our knowledge horizon even earlier, enabling new discoveries such as the feasting of a supermassive black hole less than 600 million years after the Big Bang. Using the Webb Near Infrared Spectrograph (NIRS spec), Near Infrared Camera (NIRCam), and the Near-InfraRed Imager and Slitless Spectrograph (NIRISS), researchers are revealing previously unseen details of the life of early galaxies.
Scientists collected the Webb data for this image as part of Canada’s NIRISS Unbiased Cluster Survey (CANUCS) program #1208 (PI: CJ Willott). This program uses Webb’s sensitive instruments to trace the evolution of low-mass galaxies in the early universe, revealing their star formation, dust and chemistry. The data will also help researchers study epoch of reionizationwhen the first stars and galaxies lit up the universe, they mapped the distribution of matter in galaxy clusters and understood how star formation in the cluster environment can slow to a trickle.
Bottom Line: The Webb Space Telescope imaged the stunning galaxy cluster MACS J1149 and focused on its prominent gravitational lens.
Read more: The fast growing supermassive black hole in the early universe
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