Webb Telescope Captures Light from 13 Billion Year Old Supernova

A Record-Breaking Discovery in Deep Time

The James Webb Space Telescope has shattered its own record, capturing light from the oldest supernova ever observed – a stellar explosion that occurred when the universe was just 730 million years old, roughly 13 billion years ago . This ancient cosmic event unfolded when the cosmos was just 5 percent of its current age , making it a remarkable window into the universe's earliest stellar generations.

The discovery began with an international relay race of observations. A telescope that scans for ephemeral events in space called the Space-Based Multi-Band Astronomical Variable Objects Monitor (SVOM) first detected the flash on March 14 . Within hours, NASA's Neil Gehrels Swift Observatory pinpointed the X-ray source's location on the sky, enabling subsequent observations that would pin down the distance for Webb .

Before this observation, the oldest recorded supernova was from when the Universe was 1.8 billion years old. That's a difference of more than a billion years . The breakthrough demonstrates Webb's extraordinary capability to peer deeper into cosmic history than ever before.

Coordinated Global Effort Reveals Ancient Light

The detection required precise timing and international coordination. Eleven hours later, the Nordic Optical Telescope on the Canary Islands revealed an infrared-light gamma-ray burst afterglow, an indication that the gamma ray might be associated with a very distant object. Four hours later, the European Southern Observatory's Very Large Telescope in Chile estimated the object existed 730 million years after the big bang .

But Webb had to wait months to confirm the supernova. Rather than the supernova reaching peak brightness in a matter of days or a few weeks, from our point of view, relative to this distant stellar explosion that detonated so long ago only for its light to be traveling through space all this time, it would reach peak brightness three-and-a-half months later . This delay occurs because the expansion of the universe creates a phenomenon called cosmic time dilation, which stretches the light and, consequently, the time scale of distant cosmic events. What would typically be a peak brightness lasting a few weeks was stretched, from our perspective, to occur months later .

Armed with this knowledge, Levan led a team to request what's known as Director's discretionary time on the James Webb Space Telescope. With that granted, they were ready for July 1, when JWST used its Near-Infrared Camera to detect the light of the supernova that accompanied the GRB .

Surprising Similarities to Modern Explosions

Perhaps the most unexpected finding was how familiar this ancient explosion appeared. Researchers learned that the 13-billion-year-old explosion shared many traits with modern, nearby supernovae. While that may not sound shocking, scientists expected a more profound difference . That's because early stars likely had fewer heavy elements, were more massive and didn't live as long .

"We went in with open minds," co-author Nial Tanvir said. "And lo and behold, Webb showed that this supernova looks exactly like modern supernovae" . This similarity challenges theoretical models about how the first generation of massive stars lived and died, suggesting that at least some ancient stellar explosions followed patterns remarkably similar to those we observe today.

Opening New Windows to Cosmic Dawn

"There are only a handful of gamma-ray bursts in the last 50 years that have been detected in the first billion years of the universe," Levan said. "This particular event is very rare and very exciting" . The observation proves that we can use Webb to find individual stars when the universe was only 5% of its current age .

This discovery opens new possibilities for studying the universe's earliest epochs. Webb's ability to detect both the supernova and its host galaxy provides astronomers with unprecedented tools to explore how the first stars formed, lived, and died. As more ancient supernovae are discovered, they will help scientists understand the chemical evolution of the early universe and the formation of the heavy elements that eventually made planets and life possible.

The success of this observation demonstrates the power of international cooperation in astronomy, where ground-based and space-based telescopes work together to capture fleeting moments from the universe's distant past, bringing us closer to understanding our cosmic origins.