James Webb Space Telescope identifies record-breaking jellyfish galaxy 8.5 billion light years away

University of Waterloo astronomers find the most distant jellyfish galaxy ever seen, revealing a violent universe 8.5 billion years ago via JWST.

By: AXL Media

Published: Mar 4, 2026, 9:12 AM EST

Source: The information in this article was sourced from University of Waterloo

The discovery of a distant cosmic oddity

Using the James Webb Space Telescope (JWST), researchers from the University of Waterloo have observed a "jellyfish galaxy" as it appeared 8.5 billion years ago. This discovery, published in The Astrophysical Journal, represents the farthest example of such a galaxy ever recorded. Jellyfish galaxies are characterized by long, tentacle-like streams of gas and stars that trail behind the main galactic body. This specific galaxy, located at a redshift of z = 1.156, provides astronomers with a rare look at the chaotic environmental forces that shaped galaxies when the universe was less than half its current age.

Mechanics of ram-pressure stripping

The distinctive "tentacles" of these galaxies are formed through a process known as ram-pressure stripping. As a galaxy moves at high speeds through a crowded cluster, it encounters a "headwind" of extremely hot, dense intergalactic gas. This pressure effectively pushes the galaxy's own internal gas out and away from its disk, creating trailing strands. In the newly identified galaxy, these streams are populated by bright blue clumps, which researchers have identified as newborn stars. The presence of these stars suggests that the stripped gas remains dense enough to trigger star formation outside the galaxy’s primary structure.

Strategic selection of the COSMOS field

The Waterloo team identified the galaxy while surveying the Cosmic Evolution Survey (COSMOS) Deep field. This specific region of the sky is a preferred target for deep-space researchers because it is situated far from the plane of the Milky Way, which minimizes interference from local dust and stars. Furthermore, its position allows for unobstructed viewing from telescopes in both the Northern and Southern Hemispheres. Dr. Ian Roberts, a Banting Postdoctoral Fellow at the Waterloo Centre for Astrophysics, noted that the undocumented jellyfish galaxy was spotted early in the analysis of the JWST data, immediately standing out due to its unique morphology.