Betelgeuse, the bright red star marking Orion’s shoulder, will die in a supernova explosion sometime in the next 100,000 years. That window is enormous by human standards but remarkably short in stellar terms. A 2023 study analyzing the star’s pulsation patterns concluded that Betelgeuse is in the late stages of burning carbon in its core, placing it closer to the end of its life than many astronomers previously assumed.
What’s Happening Inside Betelgeuse Now
Betelgeuse is a red supergiant roughly 700 times the diameter of the Sun, with about 20 times the Sun’s mass. If you placed it at the center of our solar system, its surface would extend past the orbit of Jupiter. Stars this massive don’t fade quietly. They burn through a sequence of heavier and heavier elements in their cores, each stage shorter than the last, until the core fills with iron and collapses.
A team of researchers studying Betelgeuse’s pulsation cycles found that the star’s behavior matches models of a star in a late phase of core carbon burning, possibly near the end of that stage. This is significant because the stages after carbon burning accelerate dramatically. After carbon, the star fuses neon and magnesium, then silicon. The carbon-burning phase lasts roughly 10,000 years. The stages that follow last thousands of years, then a century, then just days and hours before the final collapse.
The catch is that “late stage of carbon burning” still doesn’t pin down the timeline with precision. Betelgeuse could have centuries or tens of thousands of years of carbon burning left. And even after carbon burning ends, there are still several shorter stages to go. So while the finding narrows the window compared to earlier estimates, it doesn’t mean the explosion is imminent on any human timescale.
What the 2019 Dimming Told Us
In late 2019, Betelgeuse dimmed dramatically, dropping to roughly 40% of its normal brightness and sparking widespread speculation that it might be about to explode. Hubble Space Telescope observations eventually revealed a more mundane explanation: a massive blob of superhot plasma erupted from the star’s surface, passed through the outer atmosphere, cooled, and formed a cloud of dust grains. That dust cloud blocked light from about a quarter of the star’s visible surface.
The event was extraordinary by stellar standards but not a sign of imminent death. As one Hubble researcher noted, no one has ever observed what a star does right before it goes supernova, so there’s no established checklist of warning signs. The dimming told scientists more about the violent convection happening on the star’s surface than about what’s going on in its core.
How Betelgeuse Will Actually Die
Massive stars die when they run out of fuel to fuse. Each element a star burns produces a heavier element as ash, and that ash becomes the fuel for the next stage. Hydrogen becomes helium, helium becomes carbon and oxygen, carbon becomes neon and magnesium, and so on up the periodic table until the core fills with iron. Iron is the dead end. Fusing iron doesn’t release energy; it absorbs it. When the core becomes iron, it loses the outward pressure that has been holding up the star’s enormous weight. The core collapses in less than a second, triggering a catastrophic rebound that tears the star apart.
For a star of Betelgeuse’s mass, the helium-burning phase lasts several hundred thousand years. The carbon-burning phase lasts around 10,000 years. Each subsequent phase is dramatically shorter. The final silicon-burning stage, which produces the iron core, lasts only days to hours. Once the iron core reaches a critical mass, collapse is almost instantaneous.
What’s left behind after the explosion will likely be a black hole, though a neutron star is also possible. The outcome depends on how much mass falls back after the initial blast.
What It Will Look Like From Earth
Betelgeuse sits about 650 light-years from Earth. When it finally explodes, the supernova will be one of the most spectacular astronomical events in recorded history. Modeling by astrophysicists Evan Goldberg and Jared Bauer predicts the explosion will shine about as bright as the half Moon for more than three months. It would cast shadows at night and be visible in the daytime sky for roughly a year. After that initial peak, the fading remnant would remain visible to the naked eye at night for several years.
Orion would look noticeably different. The bright reddish star on the constellation’s upper left shoulder would be replaced, temporarily, by an intensely bright point of light, then eventually by nothing visible at all.
Is Earth in Any Danger?
No. At 650 light-years away, Betelgeuse is far too distant to pose a threat. A supernova would need to occur within about 150 light-years of Earth to cause measurable damage to the ozone layer or raise radiation levels on the ground. Betelgeuse is more than four times that distance. The explosion might produce a tiny, essentially undetectable change in ozone levels, but nothing that would affect life on Earth.
The flood of neutrinos from the collapse would reach Earth and pass harmlessly through the planet. Neutrino detectors around the world would register an enormous spike, giving scientists an unprecedented look at the physics of a core-collapse supernova in real time. For everyone else, the experience would be purely visual: a new light in the sky, bright enough to read by at night, lingering for months before slowly fading away.