Scientists Spot Earliest Supernova Just After Cosmic Dawn

Scientists just witnessed a stellar explosion from nearly the beginning of time itself, opening a window into how the universe's first stars lived and died.

Using the James Webb Space Telescope, astronomers spotted a supernova called SN Eos from when the universe was just a billion years old. That places it just a few hundred million years after the epoch of reionization, when the first stars began lighting up a previously dark cosmos.

The discovery marks the earliest supernova ever confirmed using detailed light analysis. Most explosions from this era are too faint to see by the time their light reaches Earth, having traveled for billions of years through space.

The team got lucky. SN Eos sat behind a massive cluster of galaxies whose gravity acted like a cosmic magnifying glass, making the explosion appear tens of times brighter than normal.

David Coulter at Johns Hopkins University and his colleagues analyzed the light spectrum and confirmed it was a type II supernova, the most common kind of stellar explosion in our galaxy. This means it came from a massive star that ran out of fuel.

The analysis revealed something fascinating about early stars. The exploded star contained very low amounts of elements beyond hydrogen and helium, less than 10 percent of what our sun has today.

That chemical signature tells astronomers exactly what they expected to find in the young universe. There simply hadn't been enough time for multiple generations of stars to form, explode, and create heavier elements.

Why This Inspires

Seeing individual stars at these distances is normally impossible. Astronomers typically observe small galaxies from this era and can only guess at average star properties.

But with SN Eos, scientists studied a single star with beautiful clarity at a distance never before possible. The data quality was good enough to confirm that early stars were fundamentally different from most stars in our local universe.

High-mass stars explode very quickly after birth, sometimes within just a million years. That means SN Eos reveals active star formation happening in its home galaxy right when the universe was emerging from darkness.

This supernova is effectively as distant as we might hope to see. Before the epoch of reionization, the universe was opaque to most radiation, like trying to see through fog.

We're witnessing a moment when photons could finally stream freely through space again, carrying messages from the universe's earliest stellar citizens across billions of years to reach our telescopes today.