A study utilizing the James Webb Space Telescope has illuminated the ages of various ancient galaxies, demonstrating that they are older and more distant than originally assumed. Webb, a cooperative effort between NASA and its European and Canadian collaborators, revisited a region of the sky made iconic by the Hubble Space Telescope’s ultra-deep field image over two decades ago. Hubble’s lengthy exposure photograph was initially ambitious, targeting a seemingly empty area. The resulting photograph was populated with thousands of remote galaxies.

With Webb, this segment of the sky is yielding new perspectives on the universe, reshaping the cosmic timeline. The MIRI Deep Imaging Survey employed Webb’s mid-infrared instrument to identify light wavelengths that are imperceptible to the naked eye. The latest discoveries are documented in the journal Astronomy & Astrophysics.

Webb enables astronomers to perceive the faint infrared glow originating from ancient stars and their structures. The telescope concentrated on the Hubble Ultra Deep Field region for 100 hours, which included 41 hours with a specific filter. The image captured weak signals from galaxies when the universe was merely a few hundred million years old.

A deep field space image acts like a core sample taken from the earth, unveiling cosmic history by slicing through billions of light-years. “To our knowledge, this represents the longest single-filter exposure achieved with (Webb) of an extragalactic field thus far,” the authors stated.

The project, referred to as MIDIS, uncovered nearly 2,500 light sources, predominantly distant galaxies. Approximately 1,000 of these have updated distance estimates based on shifts in light. Webb was engineered to investigate “cosmic dawn,” a period spanning from 100 million to 1 billion years following the Big Bang, detecting light at imperceptible infrared wavelengths. Light elongates over time and distance due to the universe’s expansion, and infrared waves can penetrate gas and dust that obscure fainter light sources.

One discovery indicated that a galaxy once considered to be 11.8 billion years old is actually closer to 13.3 billion years, dating back to a time when the universe was approximately 450 million years old. Additional objects within the MIDIS image showcase hundreds of red galaxies, some of which are dusty or harbor mature, cooler stars. Webb’s MIRI instrument is capable of identifying overlooked or misclassified ancient galaxies, exceeding the abilities of NASA’s retired Spitzer infrared space telescope.

This holds promise for scientists examining the evolution of the universe from the first galaxies to an era when star and supermassive black hole formation was at its peak. “MIDIS exceeds preflight expectations,” the authors remarked. “Deep MIRI imaging holds significant potential to characterize the galaxy population from cosmic noon to dawn.”