The Oldest, Most Distant Galaxy Ever Photographed Is 13.5 Billion Years Old

May 22, 2025

Jeremy Gray

A colorful pixelated background with pink-outlined rectangles at an angle. In the top right corner, there is a legend with "F115W" in blue, "F200W" in green, and "F277W" in red text.

The James Webb Space Telescope (JWST) has achieved another record. Scientists using the groundbreaking telescope have detected light from an ancient galaxy, MoM-z14, just 280 million years following the Big Bang. It is the most distant, oldest galaxy ever photographed, and its very existence is puzzling.

Admittedly, the galaxy does not look like much. It’s small and pixelated. However, its detection is a remarkable scientific and technological achievement that has expanded humanity’s reach ever further into the cosmos and the earliest age of the Universe.

Webb is not the first space telescope that could look into the very distant past. However, it is one thing to sense light from a super-old, super-far galaxy, and it is another thing entirely to prove that it is, in fact, a galaxy and determine precisely how old it is. This requires precise spectral analysis that Webb is uniquely able to perform thanks to its various imaging instruments, including its Near-Infrared Camera (NIRCam) and Near-Infrared Spectrograph (NIRSpec). By splitting light from cosmic objects into disparate wavelengths, scientists can learn vital information about that object’s chemical composition and then calculate its distance based on how different wavelengths of light have shifted. As NASA explains, when space expands, light is stretched. And when light stretches, it shifts more toward red light.

A scientific chart displays several wavelength filter images, a spectrum graph with labeled emission lines, and an inset showing colored bands on a small galaxy image. — **Fig. 1.** — JWST imaging and spectroscopy of MoM-z14. **Top:** 1 × 1′′ NIRCam images spanning 0.9-5μm show a compact source detected at ≳ 2μm that is entirely absent in bluer bands. Inset: NIRCam RGB image with NIRSpec MSA slitlets overlaid from our “Mirage or Miracle” survey. The source is well-centered and slit losses are modest such that the recovered spectral flux is fully consistent with the NIRCam imaging (see Appendix). **Bottom:** The prism spectrum (2D SNR spectrum on top, 1D spectrum with 1σ errors on the bottom) reveals that the disappearance of the source below 2μm in the imaging is due to an abrupt break whose sharpness implies it is a Lyman-α break. Furthermore, an array of emission lines (dashed lines) supporting the Lyman-α break interpretation is evident. The most prominent among these lines (N iv]λ1487˚A, C ivλ1548, 1551˚A, C iii]λ1907, 1909˚A) are typically the strongest lines observed in UV spectra of luminous z > 10 galaxies (e.g., Bunker et al. 2023; Castellano et al. 2024; Carniani et al. 2024).

In less than three years, the James Webb Space Telescope has entirely replaced the list of the 10 oldest known galaxies, primarily through the Cosmic Evolution Survey (COSMOS Survey) project. This incredible survey, performed by the Hubble Space Telescope, required nearly 1,000 hours of observation and is a composite of 575 separate images captured by Hubble’s Advanced Camera for Surveys’ (ACS) Wide Field Camera. A full-resolution version of this image would be a whopping 100,800 by 100,800 pixels or 10.16 gigapixels.

A deep space image showing a dark sky filled with numerous stars and faint galaxies scattered across the frame. Some stars appear brighter than others, creating a speckled, cosmic pattern. — ‘This image shows the full COSMOS field at one tenth resolution. COSMOS – the Cosmic Evolution Survey – is the Hubble Space Telescope’s largest ever survey of the Universe and was carried out by an international team of 70 astronomers. In making the COSMOS survey, Hubble photographed 575 adjacent and slightly overlapping views of the Universe using the Advanced Camera for Surveys’ (ACS) Wide Field Camera onboard Hubble. It took nearly 1,000 hours of observations. The distances to the galaxies were determined from their spectral redshifts, using ESO’s Very Large Telescope, the Subaru and CFHT telescopes in Hawaii and the Magellan telescope in Chile.’ | Credit: NASA, ESA and A. Koekemoer (STScI)

Within this massive image, scientists have identified many possible ultra-distant galaxies, and telescopes both on Earth and in space study them. Thanks to its impressive capabilities, JWST is especially good at this task. Just a year ago, Webb observed JADES-GS-z14-0, then the oldest known galaxy that was observed just 290 million years after the Big Bang.

A star-filled galaxy image with a bright blue star near the bottom left. A zoomed-in inset at the top right highlights a small, reddish, distant galaxy named "JADES-GS-z14-0," indicated with an arrow. The galaxy appears distant and faint against the dark space background. — JADES-GS-z14-0 (shown in the pullout), has a redshift of 14.32. It was, until now, the record holder for the most distant known galaxy. | Credit: NASA, ESA, CSA, STScI, B. Robertson (UC Santa Cruz), B. Johnson (CfA), S. Tacchella (Cambridge), P. Cargile (CfA).

JADES-GS-z14-0 did not hold its record for all that long. MoM-z14 is older and more distant than JADES-GS-z14-0 above, although not by much. However, another 10 million years is an awful lot when at the cutting edge of cosmic discovery.

MoM-z14 is part of the “Mirage or Miracle” survey. And despite how far MoM-z14 is away and how small it is on Webb’s sophisticated image sensors, scientists can learn a surprising amount about the galaxy.

The light from the galaxy traveled about 13.53 billion years to reach Webb, and given the understood rate of cosmic expansion, that means it is now 33.8 billion light-years away. Scientists have determined the galaxy is less than 500 light-years in diameter, much smaller than the Milky Way galaxy (105,700 light-years). Scientists have also determined that MoM-z14 is a highly concentrated galaxy with minimal dust. Further, the scientists infer that MoM-z14 is a “relatively low-res galaxy, comparable to the present-day Small Magellanic Cloud.” Granted, the SMC has a diameter of around 7,000 light-years.

A scatter plot showing absolute UV magnitude vs. spectroscopic redshift for several galaxies. Four highlighted galaxies have images and labels above the plot, with MoM-z14 shown as a blue square and others as gray squares. — **Fig. 3.** — Compilation of absolute UV magnitude vs. spectroscopic redshift for sources at the cosmic frontier. **Bottom:** The galaxies shown in silver arise from ≈ 600 arcmin2 surveyed by JWST in the first ≈ 2.5 years of its operations. See text for a full list of references. We highlight three of the most well-studied bright sources at these epochs that we reference regularly as points of comparison for MoM-z14 with square markers – GNz11 (Oesch et al. 2016; Bunker et al. 2023; Tacchella et al. 2023a), GLASS-z12/GHz2 (Naidu et al. 2022c; Castellano et al. 2022, 2024), and JADES-GS-z14-0 (Robertson et al. 2024b; Carniani et al. 2024). **Top:** 1′′ × 1′′ RGB stamps (F090W, F115W, F277W) of the sources highlighted with square markers. Three of these sources are extremely compact, with GS-z14 being the exception. For the silver points above, we extend the compilation from Roberts-Borsani et al. (2024) and include the following papers: Curtis-Lake et al. (2023); Wang et al. (2023); Fujimoto et al. (2023); Arrabal Haro et al. (2023); Harikane et al. (2024a); Hsiao et al. (2024); Napolitano et al. (2025); Kokorev et al. (2025b); Witstok et al. (2025)

What’s puzzling about MoM-z14 and some other recently discovered ancient galaxies is that not only are there more of them than expected, the relative lack of neutral gas is confusing. Scientists previously didn’t think the Universe should have reionized as early as galaxies like MoM-z14 suggest it did. There is also the unexplained star formation. Could exotic, mysterious forms of energy — like dark matter or dark energy — be involved? Maybe. There are many new questions thanks to discoveries like those of JADES-GS-z14-0 and MoM-z14.

“That the number density of luminous galaxies evolves only gradually between z ≈ 10 and z ≈ 14 is now on firm spectroscopic footing,” the researchers conclude. “The good fortune of inhabiting a Universe teeming with GN-z11s means remarkably humous z ≈ 15 galaxies in the hundreds may be within the grasp of the Roman Space Telescope. JWST itself appears poised to drive a series of great expansions of the cosmic frontier — previously unimaginable redshifts, approaching the era of the very first stars, no longer seems far away.”

The James Webb Space Telescope and other new telescopes push the boundary of human exploration and understanding farther than ever before. What was impossible to see and photograph only a few years ago is no longer so.

Image credits: ‘A Cosmic Miracle: A Remarkably Luminous Galaxy at Confirmed with JWST’ by Rohan P. Naidu et al., Open Journal of Astrophysics (submitted)/arXiv:2505.11263, 2025