The biggest explosion ever recorded is a gamma-ray burst called GRB 221009A, which released roughly 1.5 × 10⁵⁵ ergs of energy in a matter of seconds. That’s more energy than our sun will produce over its entire 10-billion-year lifetime, compressed into a flash so intense that scientists nicknamed it “the B.O.A.T.” (Brightest Of All Time). But gamma-ray bursts are just one category of cosmic violence. Depending on how you define “biggest,” several other phenomena compete for the title.
The B.O.A.T.: Brightest Gamma-Ray Burst on Record
On October 9, 2022, satellites detected a blast of gamma radiation from a star collapsing into a black hole about 2.4 billion light-years away. GRB 221009A was so bright it temporarily blinded several space-based detectors and saturated instruments that were designed to measure exactly this kind of event. Analysis from Fermi Large Area Telescope data confirmed it was the brightest gamma-ray burst ever recorded, with an extremely intense pulse lasting several hundred seconds during its main emission phase.
What makes the B.O.A.T. remarkable is its raw fluence, the total amount of energy that washed over Earth’s detectors. In terms of sheer luminosity when corrected for distance, it’s comparable to other bright gamma-ray bursts. It just happened to be relatively close by cosmic standards, giving us an unusually front-row seat. Events like this are estimated to occur only once every 10,000 years within that distance range.
How Hypernovae Outshine Supernovae
Supernovae were long considered the most powerful explosions in the universe. When a massive star runs out of fuel and its core collapses, the resulting blast releases about 10⁵³ ergs of total energy. Most of that escapes as ghostly particles called neutrinos. Only about 1% becomes the kinetic force that tears the star apart, and a tiny fraction of that, roughly 0.01%, shines as visible light over the following months.
Hypernovae blow past those numbers. These are the fading afterglows of the most powerful gamma-ray bursts, and when astronomers assume the energy radiates equally in all directions, the implied burst energies exceed 100 times the kinetic energy of a standard supernova, with that energy released predominantly as gamma radiation. The optical afterglows are also far brighter than any supernova. This gap in power is what led to the “hypernova” label in the first place.
Black Hole Mergers: Energy Without Light
In 2015, the LIGO observatory detected gravitational waves from two black holes spiraling into each other, an event called GW150914. Each black hole was about 35 times the mass of our sun, and they orbited as close as 350 kilometers apart before merging. In the final fraction of a second, the collision converted roughly three solar masses entirely into gravitational wave energy. That’s about 300 times more energy than our sun will radiate as light over its entire lifetime, released almost instantaneously.
This makes black hole mergers among the most energetic single events in the universe, though the energy escapes as ripples in spacetime rather than as light or heat. You wouldn’t see a flash. You’d feel space itself briefly stretch and squeeze, if you were close enough (and could survive).
The Longest-Lasting Cosmic Explosion
In 2021, astronomers spotted something that didn’t fit neatly into any known category. AT2021lwx brightened by a factor of more than 100 and sustained a luminosity of 7 × 10⁴⁵ ergs per second. Over roughly 440 days (in the object’s rest frame), it radiated a total of 1.5 × 10⁵³ ergs, making it several orders of magnitude brighter than any known supernova. The leading explanation is that a supermassive black hole tore apart an enormous cloud of gas, releasing energy over months rather than seconds.
What sets AT2021lwx apart isn’t peak brightness but staying power. Gamma-ray bursts are brighter at their peak but fade in seconds or minutes. This event burned with extraordinary intensity for over a year, accumulating a staggering total energy output. It holds the record as the most energetic non-quasar transient ever observed.
Quasars: Sustained Power on a Grand Scale
Quasars aren’t explosions in the traditional sense, but they dwarf every transient event in sustained energy output. The most luminous known quasar, SMSS J2157-3602, is powered by a black hole roughly 20 billion times the mass of our sun. It shines with a bolometric luminosity of about 10⁴⁷·⁸⁷ ergs per second, consuming the equivalent of about 144 solar masses of material per year. That’s swallowing roughly one sun’s worth of matter every two and a half days, converting a portion of it into radiation that outshines the B.O.A.T. when measured over any sustained period.
Quasars can maintain this output for millions of years. The total energy released over a quasar’s active lifetime dwarfs any single explosive event by many orders of magnitude.
The Ophiuchus Cluster: Biggest Known Single Blast
In 2020, astronomers confirmed a colossal cavity in the hot gas surrounding the Ophiuchus galaxy cluster, about 390 million light-years from Earth. The void is so large it could fit 15 Milky Way galaxies inside it, and it was carved out by a single eruption from the supermassive black hole at the cluster’s center. The estimated energy needed to create that cavity is roughly five times greater than the previous record holder for a black hole outburst, making it the most powerful known explosion tied to a single astrophysical event. Simulations suggest the blast may have set off sloshing motions in the cluster’s core gas that persist to this day.
Magnetar Flares: Small Stars, Extreme Bursts
Magnetars are neutron stars with magnetic fields a trillion times stronger than Earth’s. On December 27, 2004, one called SGR 1806-20 released a giant flare that briefly outshone every star in our galaxy. The total energy was about 2 × 10⁴⁶ ergs, roughly 100 times more powerful than the only two other giant magnetar flares ever observed. Despite coming from 50,000 light-years away, the burst was powerful enough to measurably compress Earth’s upper atmosphere for a fraction of a second.
Magnetar flares are small-scale compared to gamma-ray bursts, but they’re the most violent events produced by an object only about 20 kilometers across.
Was the Big Bang an Explosion?
The Big Bang is the most common answer people expect, but it wasn’t an explosion in any normal sense. An explosion involves intense heat and pressure inside a small region that pushes material outward into pre-existing space. The Big Bang was something fundamentally different: an expansion of space itself.
In the Big Bang model, objects don’t fly apart because they were kicked by a blast. Instead, the space between them grows, appearing out of nowhere, increasing distances without anything actually moving through space. Objects held together by strong forces, like atoms, planets, and people, don’t expand. Only the space between gravitationally unbound structures stretches. This distinction is possible under Einstein’s theory of gravity but has no equivalent in everyday experience. So while the Big Bang involved the most extreme conditions in the history of the universe, calling it an “explosion” misrepresents what happened. It’s better understood as the moment space itself began expanding, carrying everything with it.