Ten billion years is a long time for a secret to hide. Yet across that unimaginable gulf, a single cosmic explosion has now sent astronomers a clue so bright and so strange that it may help unravel one of the universe’s greatest mysteries. The event, a rare supernova in the early cosmos, has arrived on Earth in a way no one has ever seen before. And in its distorted light, scientists believe they may have found a new path toward understanding dark energy, the elusive force thought to be accelerating the universe’s expansion.
Dark energy makes up roughly 68 percent of everything that exists, yet it remains a ghost in modern physics, known only through its effects. Now, the discovery of supernova SN 2025wny, described in the paper Discovery of SN 2025wny A Strongly Gravitationally Lensed Superluminous Supernova at z = 2.01, gives astronomers a rare opportunity to measure the universe’s growth with unprecedented precision. It is, as one researcher puts it, a kind of cosmic gift.
“No one has found a supernova like this before, and the nature of the system means it may be able to help solve some big problems in astrophysics, such as the nature of the force that drives the expansion of the universe,” explains Dr. Daniel Perley, a reader in astrophysics at Liverpool John Moores University.
Light That Refuses To Take a Straight Path
To understand why this supernova is so important, imagine the universe as a vast, pliable fabric. When light travels across it, anything massive—like a galaxy—can tug on the fabric’s shape. That tug distorts and redirects the light, bending its path. This effect, known as gravitational lensing, is beautiful in images. But in this case, it is far more than beautiful. It is revealing.
The supernova’s light had to pass by a galaxy that sits directly in the line of sight between the explosion and Earth. As it traveled, the galaxy’s gravity split the light into separate images, each one taking a slightly different path through warped spacetime.
“We are seeing the light from this distant supernova split into multiple images, what we call ‘gravitationally lensed,’” explains Ph.D. student Jacob Wise, who first realized the true significance of what they had found.
He adds, “When light is ‘lensed,’ the different paths the light follows to get to Earth don’t all have the same length, so light moving along different paths takes variable amounts of time to reach us.”
This effect turns the supernova into a kind of natural cosmic time machine. Because the event itself shines for months, the multiple images arrive simultaneously but each reveals a different moment in its evolution. One image might show the explosion at its peak brightness, while another captures it slightly earlier or later.
In other words, astronomers are watching the same event unfold at different times, all at once.
A New Route Through the Hubble Tension
For decades, scientists have disagreed on how fast the universe is expanding. Measurements of ancient light from the afterglow of the Big Bang point to one rate. Studies of nearby galaxies point to another. Both methods are precise, both well-tested, and yet they stubbornly refuse to match. This conflict is known as the Hubble Tension.
What makes SN 2025wny remarkable is that it offers a third way. Because the time delays between the multiple images depend directly on the expansion rate of the universe, astronomers can use this supernova as a precise measuring stick.
“What’s exciting about that is that the amount of time difference between different images depends on the expansion rate of the universe,” says Dr. Perley.
The international team—working with Caltech, Stockholm University, and several other institutions—plans to measure these delays down to the finest detail. If they succeed, the supernova might finally tip the balance.
Perley puts it in clear terms “Studies of the afterglow of the Big Bang give one number for the so-called Hubble constant—the measurement of the expansion speed of the universe—while studies of nearby galaxies give a different number. Astronomers are calling this the Hubble Tension. Hence, studies of lensed supernovae could indicate which of these two numbers we should really believe.”
The explosion is not just a spectacle. It is a potential tiebreaker in one of cosmology’s most stubborn debates.
The Hunt Across the Sky
The drama of this discovery played out across multiple observatories scattered around the globe and above it. The supernova was so luminous—its light amplified by gravitational lensing—that it was first spotted not by space telescopes but by medium-sized ground facilities. The Zwicky Transient Facility in California and the Liverpool Telescope in La Palma were among the first to detect the strange brilliance.
Once recognized, the chase began. The Keck Telescopes in Hawaii joined in. Soon after, the Hubble Space Telescope and the James Webb Space Telescope shifted their gaze toward this distant eruption, gathering deeper and sharper data.
Wise recalls the moment their own team realized the true nature of the event. “Our colleagues in Stockholm first noticed the supernova but it was us who spotted that the light had been bent into multiple images. All the major observatories in the Northern Hemisphere, plus the space-based telescopes, have been looking at this but it was the Liverpool Telescope that got there first.”
From local telescopes to the most powerful instruments humanity has ever placed in orbit, the discovery became a global pursuit, each new observation revealing more detail in a cosmic puzzle billions of years in the making.
Why This Discovery Matters
This is not simply the story of a bright explosion in a distant galaxy. It is a story about how the universe grows. Dark energy, the mysterious force driving cosmic expansion, remains one of the most profound unknowns in science. To understand it is to understand the fate of the cosmos itself.
SN 2025wny offers a rare and precious way to measure the expansion of the universe using pure observation, untouched by the assumptions that complicate other methods. By analyzing the different arrival times of its lensed images, astronomers hope to determine how fast space is stretching—and therefore learn more about the force accelerating that stretch.
The universe may be vast and ancient, but sometimes, across unimaginable distances, it sends us exactly what we need. A supernova that burst into brilliance ten billion years ago has traveled through warped spacetime to reach us today, carrying with it the possibility of resolving one of modern astronomy’s most troubling contradictions.
It is a reminder that the cosmos still surprises us. Still challenges us. Still speaks, if we know how to listen.
More information: Joel Johansson et al, Discovery of SN 2025wny: A Strongly Gravitationally Lensed Superluminous Supernova at z= 2.01, The Astrophysical Journal Letters (2025). DOI: 10.3847/2041-8213/ae1d61
