Supernova watch

Is Betelgeuse going to explode? Star's brightening tells a different story — for now

"Although the present dimming cycle seems over, it will be very important to see what happens next."


The chances of seeing a star explode in our skies any time soon have just dramatically decreased.

Our one hope for the show of a life time, a star in the constellation Orion called Betelgeuse, seems to be well on its way to recovery after weeks of worrying behavior.

Betelgeuse caught the attention of astronomers in December, 2019 when it was announced that the star began dimming unexpectedly.

Now, the red supergiant star Betelgeuse is getting brighter again, according to the latest data posted this week to The Astronomer’s Telegram. Currently, Betelgeuse is at around 40 percent of its usual brightness, according to The Astronomer’s Telegram, the data show.

It is good news for Betelgeuse lovers: Things had looked dire for the star. By January 2020, Betelgeuse had dimmed by 25 percent.

This side by side comparison shows the dimming of Betelgeuse from January, 2019 to December, 2019.


The unprecedented dimming led astronomers to believe, and, for some, secretly hope, that the star was on the verge of exploding in a massive supernova.

Supernova science

Supernovas happen when a star nears the end of its life. As it ages, it runs out of fuel and eventually collapses under the strength of its own gravitational force.

Edward Guinan, professor at Villanova University, has observed Betelgeuse since 1981. He was among the first to notice the star's dimming. Guinan reported his observations on The Astronomer's Telegram in December, sparking all the supernova hype.

Inverse first spoke to Guinan in January, and he predicted that the star would soon recover from this unusual episode. Turns out, he was right.

"I am happy that my prediction about the behavior of the star turned out to be correct," Guinan tells Inverse.

"But I would have preferred to be wrong, and have the star continue getting dimmer and dimmer and then explode as a fantastic, unforgettably bright supernova."

Courtesy of Edward Guinan

It may seem strange to be so enthused for the star you study's death to be at hand, but Betelgeuse’s explosive death would have presented a one-in-a-lifetime opportunity for scientists.

Supernovae tend to occur in stars billions of lightyears away and are usually seen millennia after they blow. But Betelgeuse is right in our cosmic neighborhood, less than 700 lightyears from Earth. As a result, astronomers observing the star would have witnessed the entire process preceding the massive explosion, enabling them to better understand the mechanics that govern the death of stars.

But all that promise seems to be coming to an end, as this playful star climbs back up on the charts of the brightest stars in our night sky.

“Photometry secured over the last [two] weeks shows that Betelgeuse has stopped its large decline of delta-V of ~1.0 mag relative to September 2019,” astronomers announced on February 22.

That means that the star is not dying after all, and the already narrow chances of a supernova are gone.

We may not be getting our coveted supernova explosion after all.

ESO, L. Calcada

Why did Betelgeuse dim?

Betelgeuse is a variable star, meaning that it regularly ranges in brightness, from between +0.0 and +1.3. And although its recent dimming reached unprecedented levels, the whole event may have just been another part of its lifecycle.

Astronomers are currently trying to understand what may have caused the star to temporarily lose its brightness.

"Betelgeuse has multiple cycles of variability that make its dimming complicated and it is a remarkable triumph for our understanding of stellar evolution that this can be predicted at all," Andy Howell, staff scientist at Las Cumbres Observatory Global Telescope Network, tells Inverse.

Even if we did not get the supernova we were hoping for, the dimming event still provides an interesting insight into the cycles of variability of a red supergiant star.

"Although the present dimming cycle seems over, it will be very important to see what happens next," Guinan says.

"Will this trend continue or will the star recover, get brighter and return to its previous behavior as business as usual?"

Betelgeuse will remain under the close watch of astronomers for now, a cosmic favorite for its known brightness and close proximity.

"Long live the king of the red supergiants," Howell says. "But not too long."

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