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Betelgeuse

What will become of one of the most famous—and most temperamental—stars?

Published
supernova
Carnegie Institution for Science
A one in 10 million shot.
  • Orion’s shoulder trouble

    Image copyright: Morigan221

    Arguably the most recognizable constellation in the night sky, Orion includes seven bright stars that form an hourglass shape resembling the figure of a man—a hunter, according to Greek mythology. For millennia, cultures around the globe have spotted Orion in the skies and incorporated it into their folklore and mythologies.

    Part of the endless intrigue surrounding Orion is no doubt thanks to the fact that it contains two of the brightest stars visible in the sky—Rigel (Beta Orionis), which represents Orion’s left foot, and Betelgeuse (Alpha Orionis), representing Orion’s right shoulder. But after thousands of years of dependability, the red supergiant is acting strangely, leading some to believe it’s on a path to self-destruction.

    Will Betelgeuse soon be browsing The Handbook for the Recently Deceased? Grab your telescope and let’s find out.

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  • By the digits

    640: Lightyears Betelgeuse is from Earth

    950: Times larger Betelgeuse is than the sun

    10 million: Years old Betelgeuse is (maybe a little less)

    135,000: Times brighter than the sun

    0.5 seconds: Time it takes for the core of a star the size of Betelgeuse to collapse

    5,000: Years from now that Betelgeuse will collide with a strange, dusty “wall”

    40,000: Years ago that Betelgeuse started expanding into a red giant star

    1: Academy Awards won by the film Beetlejuice

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  • The way we ✨ now

    Image copyright: NASA

    Betelgeuse has long been one of the top 10 brightest observable stars, but since October 2019, it’s been twinkling on and off of the list. By the end of the year, the star wasn’t even in the top 20. Because Betelgeuse is a variable star, this isn’t entirely unusual. But this is the dimmest it’s been in nearly a century, and astronomers have recently made another startling discovery: The star may have changed shape.

    The European Southern Observatory announced that its recent high-resolution photographs showed that the normally circular star has taken on an oval appearance. Why? No one is entirely sure, because Betelgeuse is a pretty hard ball of gas to pin down.

    While there have been many theories that Betelgeuse is about to go supernova—explode and die—the recent re-brightening of the star has some astronomers declaring that it was merely going through a “fainting spell,” and is likely out of the woods for now.

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  • Origin story

    Betelgeuse has long fascinated scientists and soothsayers alike, so we have no way of knowing who first noticed Orion’s red right shoulder. But we do know that Sir John Herschel was the first to observe and record the changes in the star’s apparent luminosity, a discovery he announced in 1840. In his 1849 work Outlines of Astronomy, Herschel wrote, “The variations of Alpha Orionis, which were most striking and unequivocal in the years 1836-1840, within the years since elapsed became much less conspicuous.”

    What does its funny name mean? Technically, nothing. According to NASA, it’s “a corruption of the original Arabic phrase Yad al-Jauza’, meaning ‘hand of the giant one,’” but according to Merriam-Webster it’s a corruption of bayt al-jawzā’, or “house of the twins.” As a result there’s no single proper pronunciation.

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  • Fun fact!

    Image copyright: Giphy

    The 1988 film Beetlejuice almost had a different name. Studio execs hated the star-inspired title and suggested that Tim Burton consider House Ghosts instead. Tongue firmly in cheek, Burton said they might as well call it Scared Sheetless—and the studio loved it. In the end, the director put his foot down.

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  • What’s going on with Betelgeuse?

    There are two possibilities: Betelgeuse will brighten again and continue its pattern, or it will explode.

    If it’s the latter, Betelgeuse will keep fusing increasingly large elements at its core, until it starts producing iron in the last second of its life. Gravity takes over and the star collapses; photodisintegration turns iron into helium, releasing massive amounts of energy and allowing the iron core to collapse.

    Then, the strong nuclear force pushes back. The collapsing and rebounding causes a “traffic jam,” creating unimaginably intense heat, eventually producing a shock wave that will light up the night sky.

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  • Million-dollar question: When was the last visible supernova?

    It’s not exactly a common occurrence: The last visible supernova in the Milky Way, known as Kepler’s Supernova, was in 1604. When the phenomenon happened, astronomer Johannes Kepler believed the world had witnessed the birth of a new star. It wasn’t until centuries later that modern scientists realized that he had actually seen just the opposite—the star’s death.

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  • Another million-dollar question: What happens to Earth if Betelgeuse explodes?

    Image copyright: NASA

    This is not a Yellowstone supervolcano situation, so don’t worry. Astronomers believe Betelgeuse’s explosion wouldn’t do any significant damage to Earth. The radiation would likely have some measurable effects on the environment, but probably not much, thanks in part to the earth’s magnetic field. Whatever radiation did manage to get through “will be so low-density that it will have less of an impact on you than the banana you had at breakfast,” reports Ethan Siegel for Forbes.

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  • Quotable

    “It’s fun to watch stellar evolution in real time. It’s doing things we’ve never seen before in this star, and it’s not clear we’ve seen them in any other star, either.”

    Andrea Dupree, Harvard-Smithsonian Center for Astrophysics

    “The phrase ‘we are all made of stardust’ is one we hear a lot in popular astronomy, but where exactly does this dust come from? Over their lifetimes, red supergiants like Betelgeuse create and eject vast amounts of material even before they explode as supernovae.”

    Emily Cannon, PhD student at KU Leuven, specializing in red supergiants

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  • This one weird trick!

    Betelgeuse has been described as “boiling oatmeal” because of the way it brings energy from its center to the surface. (Betelgeuse’s energy is thermonuclear, however, while your morning porridge is not.) What it’s doing with all of that energy is actually a pretty neat trick: It’s creating new stars. Eventually. Betelgeuse is constructing heavier and heavier elements, from hydrogen to helium to carbon to oxygen to iron. And someday, when it goes supernova, it will violently expel all of those elements out into the universe, creating brand new stars.

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