Betelgeuse is destined to explode as a Type IIP supernova, becoming exceptionally bright and leaving ... [+]
Go outside tonight when it gets dark and look to the southwestern sky. Can you see Orion’s Belt? Those three bright stars—Alnitak, Alnilam and Mintaka—are unmistakable, but so is a bright star just above them, the ruddy-colored supergiant Betelgeuse. An icon of the winter night sky in the northern hemisphere, it’s the closest red supergiant star to the solar system.
This “shoulder” star in Orion has a boiling surface and is supposed to be the tenth brightest in the sky. But according to a new study, its brightness has dipped by 0.5 magnitude since late January, according to EarthSky and Sky & Telescope. Is Betelgeuse about to explode?
Exciting Prospect
It’s not likely to happen now, but we do know that Betelgeuse will definitely explode as a supernova sometime in the next 100,000 years. In the lifetime of stars, that’s really soon, but for astronomers, it’s a hugely exciting prospect because a supernova hasn’t been observed going off in our Milky Way galaxy since the 17th century.
A 2023 paper predicts that Betelgeuse’s core will exhaust its carbon fuel in less than 300 years and that “a core collapse leading to a supernova explosion is expected in a few tens of years.”
That makes any slight changes to its brightness very interesting.
These images, taken with the SPHERE instrument on ESO’s Very Large Telescope, show the surface of ... [+]
‘Great Dimming’
Betelgeuse—also known as Alpha Orionis—is 20 times the mass of the sun and 1,400 times its size. It’s 650 light years distant from the solar system, so whatever is going on with it right now happened 650 years ago—and we’re only just now seeing its light. Or lack of. But there’s no need to worry because Betelgeuse is well beyond the 50 light-years “supernova danger zone.”
In late 2019 and early 2020, Betelgeuse was in the headlines because of its sudden “great dimming,” during which it slumped to about 40% of its usual brightness before gradually returning to normal. It also changed shape.
Although it was already known to be a variable star whose brightness shifted over about 400 days and over six years, nothing as dramatic as its “great dimming” had ever been observed.
Mass Ejection
Several theories for Betelgeuse’s “great dimming” were put forward, including:
- Convection caused a cold spot in its southern hemisphere, making it appear dimmer.
- It’s a normal variation in brightness caused by pulsations or interactions with other stars.
- It’s dust, something that red supergiant stars eject a lot of.
However, images from the Hubble Space Telescope confirmed that a “burp” from within Betelguse had unleashed a mass ejection of material that became a dust cloud obscuring some of the star’s brightness as seen from Earth.
This image shows the location of the red supergiant star Betelgeuse in the constellation of Orion ... [+]
‘Ring Of Fire’
In December last year, Betelgeuse was very briefly back in the news when an asteroid eclipsed it for about 12 seconds. A very rare night sky event, asteroid 319 Leona caused a short “ring of fire” annular eclipse as it passed across the star.
One day, Betelgeuse will explode as a Type IIP supernova, becoming exceptionally bright and leaving behind a neutron star. As it does, it could shine as bright as a full moon for a few months before effectively disappearing to the naked eye. Although it may be visible during the day, it would be a stunning sight at night. However, for that, Betelgeuse would have to “go supernova” between December and April.
If the red supergiant star is about to explode, let’s hope it happens soon—before it sinks beneath the post-sunset horizon and into the sun’s glare.
Wishing you clear skies and wide eyes.
