On a clear winter night, stargazers are often drawn to the constellation Orion, with its striking bright red star, Betelgeuse. For centuries, this star’s curious dimming has intrigued skywatchers, and today, astronomers understand why. Betelgeuse is a red supergiant, a massive star nearing the end of its life, about 700 times larger than our Sun. At some point, this star will end its days in a spectacular explosion known as a supernova. This rare event has fascinated scientists, who have long predicted what this grand celestial show might look like from Earth.

When Betelgeuse began dimming significantly in 2019, some astronomers wondered whether this might be a prelude to its final supernova. Though it was unlikely, the possibility sparked excitement among both the scientific community and the public. A supernova visible from Earth is rare, and Betelgeuse’s explosion is expected to put on a stunning display for our planet when it happens, possibly within the next 100,000 years.

Astronomers at the University of California, Santa Barbara, led by Andy Howell, wanted to get a more accurate idea of what a Betelgeuse supernova would look like from Earth. Using data from Supernova 1987A—the closest star to explode in recent history—they developed simulations to predict the brightness and visibility of such an event. According to their findings, when Betelgeuse does explode, it will shine as brightly as a half-moon for over three months. Its brightness would be concentrated in a single point in the sky, creating an intense light source that would be visible during the day for about a year and remain in the night sky for several years. After the explosion fades, the familiar constellation of Orion will have lost its bright left shoulder.

But despite its brilliance, a Betelgeuse supernova would pose no threat to life on Earth. Located 724 light-years away, it is far beyond the range in which a supernova’s radiation could harm us. However, its brightness could still disrupt certain aspects of life on Earth. Howell suggests that animals that navigate by the Moon might become confused by this second bright object in the sky. Astronomers themselves would face challenges, too, as Betelgeuse’s brilliance would make observations difficult, overwhelming many telescopes.

If the explosion does occur in our lifetimes, we’ll have some advance notice. Earth-based instruments would detect neutrinos or gravitational waves from Betelgeuse’s explosion up to a day before the visible light reaches us. This lead time would give people around the world a chance to prepare for the spectacular light show, staying up to witness the event.

Even without the supernova, Betelgeuse continues to intrigue astronomers. Its size and proximity make it an excellent candidate for studying the later stages of a star’s life. Red supergiants like Betelgeuse undergo significant changes as they burn through their nuclear fuel. These stars swell and release vast amounts of gas and dust, creating temporary dimming and brightening effects. Sometimes, material erupts from their surfaces, creating a violent cosmic belch that alters the star’s brightness.

Scientists have several theories to explain Betelgeuse’s current dimming. One possibility is that the material ejected from the star is blocking its light, making it appear dimmer. Alternatively, it could be a combination of factors, with various processes inside the star contributing to its fluctuating brightness.

In any case, Betelgeuse offers a unique opportunity for astronomers to observe a dying star up close. Its behavior may help researchers gain new insights into the final stages of life for red supergiants, making it a key subject of ongoing study.

So, while we wait for the grand finale, Betelgeuse continues to captivate our imagination and expand our understanding of the cosmos, offering a front-row seat to one of the universe’s most dramatic spectacles.