The red giant Betelgeuse could explode as a supernova bright enough to see by day

High in the winter sky, marking the shoulder of the constellation Orion, sits a star nearing the end of its life in dramatic fashion. Its orange-red glow has fascinated skywatchers for centuries, but in the past few years it has also become one of the most closely studied stars in astronomy after behaving in ways scientists had never documented before. Whenever its eventual demise finally arrives, astronomers expect it to produce one of the most spectacular events anyone alive could witness, though nothing about current data suggests that moment is close at hand.

What Makes This Red Supergiant Different

According to NASA’s own description of the star, Betelgeuse sits roughly 700 light-years from Earth and is only about 10 million years old, far younger than the sun’s nearly 5 billion years. Despite its youth, Betelgeuse is much more massive than the sun, which means it burns through its nuclear fuel far faster and will have a correspondingly shorter total lifespan. The star is about 700 times the size of the sun and roughly 15 times more massive, large enough that if it replaced the sun at the center of the solar system, its outer edge would stretch past the orbit of Jupiter.

Betelgeuse is also unusually bright, typically ranking among the ten brightest stars visible from Earth and shining somewhere between 7,500 and 14,000 times more luminously than the sun, even though its surface runs cooler, at roughly 6,000 degrees Fahrenheit compared with the sun’s approximately 10,000 degrees. Astronomers classify it as a semiregular variable star, meaning its brightness naturally rises and falls on a roughly 400-day cycle layered on top of a longer cycle spanning about five years.

Humans have almost certainly watched this star for as long as they have looked up at the night sky, and its record in written astronomy stretches back centuries. German astronomer Johann Bayer catalogued it as Alpha Orionis in 1603, a name it retains even though the neighboring star Rigel is now known to shine brighter. British astronomer John Herschel documented Betelgeuse’s changing brightness in 1836, and NASA notes that evidence of its variability likely appears even earlier in Aboriginal oral traditions, long before telescopes existed to confirm it.

The Great Dimming of 2019 and 2020

That normal variability took an unusual turn in the fall of 2019, when Betelgeuse dimmed by about 60% over just a few months, an event astronomers now call the Great Dimming. The sudden drop briefly fueled speculation that the star might be entering a pre-supernova phase, but by April 2020 its brightness had returned to normal, leaving the cause a mystery for more than a year.

Using data from NASA’s Hubble Space Telescope and other observatories, scientists eventually determined that Betelgeuse had ejected a massive piece of its own visible surface in an event known as a surface mass ejection, expelling roughly 400 billion times as much material as the sun typically releases in a coronal mass ejection. The ejected material, which likely weighed several times as much as Earth’s moon, cooled into a dust cloud that temporarily blocked light from about a quarter of the star’s surface as seen from Earth, producing the dimming that had puzzled observers.

Timelines That Range From Decades to 100,000 Years

NASA’s current guidance states plainly that Betelgeuse will eventually explode as a supernova, but that scientists do not expect this to happen for roughly another 100,000 years, after which the star would collapse into either a neutron star or a black hole depending on how much material remains. That long-range estimate reflects the traditional understanding of how massive stars evolve through successive stages of nuclear fusion before their cores finally collapse.

Not every researcher agrees the timeline is that distant. A 2023 study examining Betelgeuse’s pulsation periods concluded the star is in a late stage of core carbon burning and suggested it could be a candidate to explode within “tens of years” rather than millennia, according to an analysis published by EarthSky. The same reporting notes that the study’s authors acknowledged they cannot determine precisely how much carbon-burning time remains, since surface observations reveal little about conditions deep inside the star, leaving the explosion timeline anywhere from decades to thousands of years.

Why Earth Has Nothing to Fear From the Blast

Regardless of when Betelgeuse finally explodes, its distance keeps Earth well outside any zone of physical danger. Research cited by EarthSky indicates a supernova would need to occur within about 160 light-years of Earth to pose a direct hazard, and Betelgeuse sits roughly four times farther away than that threshold. When the explosion does happen, NASA and other astronomers expect it to become extraordinarily bright, potentially rivaling the full moon and remaining visible even in daylight for a period before fading, an event with no verified precedent in recorded human history at such close range.

Scientists have also recently identified a possible companion star nicknamed Betelbuddy, first announced in 2024 and further detailed by Carnegie Mellon University researchers on October 8, 2025, who found it to be a young, sun-sized star rather than the compact dead star some had expected. Its gravitational wake through the gas surrounding Betelgeuse may help explain the star’s unpredictable dimming, giving astronomers another variable to track as they continue monitoring one of the sky’s most closely watched stars for whatever comes next.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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