Webb image reveals distant galaxies warped and magnified by MACS J0454.1-0300

The European Space Agency released a James Webb Space Telescope image of galaxy cluster MACS J0454.1-0300 on 29 September 2026, showing how its gravity bends and magnifies light from more distant galaxies. The image reveals hundreds of galaxies absent from a 2014 Hubble view of the same cluster, giving astronomers a more detailed look at objects behind it.

In the image, the brilliant golden galaxies belong to MACS J0454.1-0300. The orange galaxies concentrated to one side are farther away, ESA says, even though they appear in the same field. Their light has passed through the cluster’s gravitational influence on its way to the telescope, leaving some images stretched into arcs or repeated. Distinguishing those background objects from cluster members is essential to understanding what the picture shows.

How MACS J0454.1-0300 bends light from distant galaxies

A galaxy cluster contains enough mass to bend the path of light travelling past it. In this case, MACS J0454.1-0300 acts as a gravitational lens: it changes the apparent shape and brightness of galaxies farther away. ESA says the effect can bring distant galaxies, star clusters and even individual stars into view when they would otherwise be too faint for telescopes to detect. The arcs are therefore images of background sources seen through the cluster’s gravity, rather than galaxies physically stretched into those shapes.

The effect extends beyond the most prominent orange arcs. ESA points to small reddish galaxies near the edges of the Webb frame whose images have also been bent. The cluster itself is distant: ESA says its light has travelled for so long that the image shows it as it was when the universe was about eight billion years old. The galaxies behind it are seen at still earlier stages of cosmic history.

What the Webb image brings into view

ESA also reports bright ‘knots’ within the lensed regions corresponding to structures as small as five light-years across. Some appear magnified by a factor greater than 300. That magnification helps explain why features on such small scales can be identified in sources so far away. The figures are ESA’s account of the observations accompanying the image, rather than a newly established measurement from a peer-reviewed paper cited in the release.

What changed since Hubble’s 2014 image

The gravitational lens was known before this Webb release. In March 2014, ESA/Hubble published an image of MACS J0454.1-0300 and described distant galaxies behind it as elongated arcs, amplified and distorted by the cluster’s gravity. That earlier observation established the basic view of the cluster as a natural magnifying glass. Webb adds detail to an already studied field; its image does not mark the discovery of gravitational lensing there.

ESA says the Webb image reveals hundreds of galaxies missing from the earlier Hubble picture because Webb is more sensitive to their much redder light. The galaxies were already there. Comparing the images illustrates a change in what the telescopes can show, rather than a sudden appearance of hundreds of newly formed galaxies. The earlier Hubble release provides a direct visual comparison for readers who want to see how the field looked in 2014.

Earlier studies of the cluster’s mass and structure

Independent research also treated this cluster as a lens well before the new image. A 2011 strong-lensing analysis of MACS J0454.1-0300, also identified as MS 0451.6−0305, modelled previously known multiple images. For a source at redshift 2.9, the researchers estimated an Einstein radius of 19 ± 2 arcseconds, a measure associated with the lensing geometry. They estimated about 0.82 × 10^14 solar masses inside the corresponding critical curve. Those are model-based historical estimates, not measurements newly produced by Webb’s 2026 picture.

A separate 2020 study combined Hubble lensing data with XMM–Newton observations to examine the distribution of matter and gas around MS 0451−03. It reported three possible filaments and six group-scale substructures across the region it mapped, and described an elongated dark-matter core with two components. The authors inferred a past merger from the mass and gas distributions and optical spectroscopy. That work supplies context for the cluster’s complex structure; it is separate from ESA’s interpretation of the distant, apparently merging galaxy group visible through the lens.

The new image draws on two Webb observing programmes, numbered 5058 and 6882, according to ESA. The immediate result presented in the 29 September release is the image and ESA’s description of what can be seen in it. A further analysis of the newly visible galaxies or the tiny magnified regions is not established by the sources cited here, so their properties should be read as the agency’s reported interpretation of these observations.