Peril in Orion! Beware Betelgeuse?

H. Raab's photos: the constellation Orion, showing changing brightness of Betelgeuse (Orion's right shoulder), (February 22, 2012 (left); February 21, 2020 (right). via Wikipedia, used w/o permission.
H. Raab’s photos of Orion: February 22, 2012 (left); February 21, 2020 (right)

IAU, Sky and Telescope magazine; Roger Sinnott, Rick Fienberg's sky chart: the constellation Orion.Betelgeuse, the bright red star in Orion’s right shoulder, is a semiregular variable star, with small periods of 185 days and 2,100 days and a main period of around 400 days.

It will explode at any moment, and we’re right next door.

If I had any sense, from one viewpoint, I’d talk about the ozone hole, denounce forever chemicals and promote a ‘Save the Panda’ fund I’d set up.

Or maybe indulge in free association inspired by Revelation and Gematria, and slip in hints that your only hope is to give me money.

Yeah. That kind of trouble I don’t need. Besides, I suspect the weird mix of numerology and Bible trivia that infested ‘Christian’ radio during my youth is no longer in vogue.1

So instead, I’ll look at the last two times Betelgeuse was newsworthy. Then I’ll talk about cosmic scale, stars and whatever else comes to mind.


Brian H. Gill's 'Totally Depressing News Network' logo. (2018)News media can serve useful purposes.

But I wouldn’t mind if journalists could dial the angst back a bit. And convince their editors that wasting time on a quick Google search wasn’t really wasted time.

That said, coverage of the last two times Betelgeuse threatened our fair planet could have been worse.2 Some was downright informative.


ESO, P. Kervella's image: Betelgeuse, seen in near-infrared; showing stellar disk and asymmetric extended atmosphere. (July 2009)
Betelgeuse in near-infrared, stellar disk and asymmetric extended atmosphere. ESO, P. Kervella (July 2009)

NASA Space Place's illustration: 'What holds stars together?' (2017)The 2009-2012 headlines got started when Townes, Wishnow, Hale and Walp said that they’d observed a change in Betelgeuse’s apparent diameter.

At one wavelength — 11.15 microns — the visible disk of Betelgeuse had shrunk by 15% in 15 years: 1993-2009. They were right about that.

But other scientists, measuring the star’s diameter at other wavelengths, found that Betelgeuse had gotten a tad bigger.

The last I checked, the consensus is that Betelgeuse’s envelope — a sort of extended atmosphere around the star — has changed.

Someone, I don’t know who, apparently mentioned that Betelgeuse will eventually become a supernova; and that stars shrink before exploding.

I only found one Betelgeuse-Mayan Apocalypse article, with Star Wars for extra flavor. And that one was comparatively low-key. Maybe the more creative journalistic outfits don’t regard their online content as evergreen, and that’s another topic.

Now, assuming that current models of how stars work are somewhat accurate, Betelgeuse will explode very soon. On a cosmic scale.

Estimates, based on various criteria, say that the the Betelgeuse supernova will happen somewhere between 100,000 and 1,000,000 years from now.

Compared to the 13,780,000,000 years, give or take, that this universe has been around; that’s very soon. Measured against the 24-hour news cycle, not so much.

As for being close, Betelgeuse isn’t in our back yard. But it’s arguably in our neighborhood.

Betelgeuse is between about 500 and 600 light-years away. Stepping back a little, it’s about 26,000 light-years to our galaxy’s center — in the general direction of Delta Sagittarii — and 2,500,000 light-years to the next Milky Way-sized galaxy.3

So on a cosmic scale, I’d say Betelgeuse is several doors down the block.

Distances, Safe and Otherwise
NASA, ESA, J. Hester and A. Loll (Arizona State University)'s image: the Crab Nebula, a supernova remnant ca. 6,500 light-years away, in the constellation Taurus. (1999, 2000 for optical images)
The Crab Nebula in optical, radio, infrared, ultraviolet, and X-ray wavelengths.

Light from a supernova that was roughly 6,400 light-years away reached Earth in the year 1054, when Edmund the Old was king of Sweden.

We know about it because Chinese astronomers recorded it as a “guest star”.

An English astronomer spotted the supernova’s remnant in 1731. In 1921, an American astronomer noticed that the Crab Nebula is expanding. Eventually, that let scientists work out when it had started billowing out; and that lined up with the 1054 guest star.

Right now, the Crab Nebula is about five and a half light-years across. If we’d been as close to it as we are to Alpha Centuari, it’d be more than an astronomical object of interest.4

Estimates and an Example

NASA/CXC/M. Weiss' illustration: SN 2006gy. (2007)If Betelgeuse was closer, say 50 light-years away, and reached the supernova point in its development this year, then folks who’d invested in sun block could celebrate.

Seems that 50 light-years is where a supernova’s particles and radiation would start seriously affecting our ozone layer. That could be bad news for phytoplankton: and, indirectly, us.

Bad news, but not necessarily catastrophic. Supernovae happen. Some have happened near Earth. Most recently, very likely, about 2,600,000 years back. Give or take a few hundred thousand.

That’s right around the end-of-Pliocene mass extinction.

At the time, Oldowan tools were standard equipment for many folks.

Acheulean tech was around 900 millennia in the future, and the data storage technology we call writing was uncounted ages beyond that. So we don’t know what folks thought about the bright new star in their sky.

Now, about the mass extinction. By journalistic standards, it was an “unprecedented” catastrophe. Some plankton and mollusks died. So did megalodons. But for the most part, life went on.

The supernova may have been part of the Scorpius-Centaurus association of stars. That’s the nearest bunch of huge stars that haven’t exploded yet.

At the moment, the Scorpius-Centaurus association is about 420 light-years out, roughly in the direction of Alpha Lupi and Theta Centauri. Back when the supernova went off, it was closer: about 130 light-years.

That’s well outside the 50 light-year danger zone.

Or maybe it’s 25 light-years. Some scientists say that a supernova closer than that could do serious damage to Earth’s upper atmosphere. But we aren’t sure about the safe distance.5 Not yet.

Looking Ahead, Looking Back

Oldowan tools found in Kenya: 'The analysis of wear patterns on 30 of the stone tools found at the site showed that they had been used to cut, scrape and pound both animals and plants' (February 10, 2023) Text, BBC News; photo, ReutersSooner or later, there’ll be another uncomfortably-close supernova.

Based on past experience, life will go on after that. So, I think, will we.

Partly because the end-of-Pliocene mass extinction didn’t end us.

Granted, we looked a bit different then.

Or, from another viewpoint, we look different now: taller, with too much forehead and not nearly enough face.6 And that’s yet another topic.

Betelgeuse, The Great Dimming and After
ESO/M. Montargès et al, Center for Astrophysics Harvard and Smithsonian, SPHERE instrument on the European Southern Observatory's Very Large Telescope's photos: Betelgeuse (January 2019, December 2019, January 2020, March 2020)
ESO’s SPHERE photos: Betelgeuse (January 2019, December 2019, January 2020, March 2020)

Studio Foglio's Mr. Squibbs, used w/o permission.Maybe it’s just as well that news media was in full cry with the COVID-19 pandemic and political pandemonium in 2020.

It wouldn’t have taken a great leap of imagination to transform this expression of scientific interest into a shocking revelation. Maybe something like ‘mad scientists seek to doom us all!’

The scientists who are hoping for a supernova
If star on Orion’s shoulder goes supernova, Fermilab experiment will collect data bonanza
uchicago news, adapted from a story by Scott Hershberger originally posted by Fermilab (October 14, 2020)

“In late 2019, Betelgeuse, the star that forms the left shoulder of the constellation Orion, began to noticeably dim, prompting speculation of an imminent supernova. If it exploded, this cosmic neighbor a mere 700 light-years from Earth would be visible in the daytime for weeks. Yet 99% of the energy of the explosion would be carried not by light, but by neutrinos, ghost-like particles that rarely interact with other matter.

“If Betelgeuse does go supernova soon, detecting the emitted neutrinos would ‘dramatically enhance our understanding of what’s going on deep inside the core of a supernova,’ said Sam McDermott, a theorist with the Fermi National Accelerator Laboratory….”

Then again, maybe not.

I like to think that even the most desperate news editor, having received his science education during late-night mad scientist marathons, would realize that we can’t make stars go boom.

I’d also like to say that they don’t make films like these any more:

  • Terror of Mechagodzilla (1975)
  • Frankenstein Meets the Spacemonster (1965)
  • X: The Man with the X-Ray Eyes (1963)

But cultural content, including film reviews, shows up in my news feeds, and that’s yet again another topic.

As it turned out, the 2019-2020 dimming of Betelgeuse wasn’t the prelude to a supernova.7 Probably.

Betelgeuse’s Great Dimming: The Aftermath
Colin Stuart, Sky & Telescope (August 25, 2022)

“…By piecing together data from a slew of telescopes, including the Hubble Space Telescope, [Center for Astrophysics, Harvard & Smithsonian’s Andrea] Dupree is pointing the finger at an event called a Surface Mass Ejection (SME). Our own Sun regularly burps material from its corona, ejecting a billion tonnes of solar material — about the mass of Mount Everest. But Betelgeuse’s SME spit out 400 billion times more material, equivalent to several times more mass than the Moon. As the ejected material cooled, it formed a cloud of dust that partially blocked, and thus dimmed, our view of Betelgeuse….

“…The event seems to have had a profound effect on Betelgeuse’s more regular pulsations. Astronomers have observed the star for centuries and noticed that it goes through cycles of brightness variations with a period of 400 days. This pattern seems to have completely disappeared since The Great Dimming, perhaps as result of a reshuffling of material in the star’s interior. ‘Betelgeuse continues doing some very unusual things right now,’ Dupree says….”

On the other hand, maybe that stellar megaburp was but a prelude to a nearby supernova. My guess is that it’s not.

But if it is, then scientists around the world are going to be scrambling to get as much data as they can.

And the rest of us can either ignore the new light in our sky, fill the pockets of ‘Sam’s SuperSafe Supernova SuperShelter’ hucksters — or, if it’s summer, set up the lawn chairs, get popcorn and lemonade; and enjoy the show.

A Variable’s Variable Etymology

Frederik de Wit's 'Planisphaerium coeleste' star chart. (1670) Frederik de Wit, via Wikimedia Commons, used w/o permission.Like a great many other stars, Betelgeuse got its name from Arabic: bat al-jawzā’ or maybe Yad al-Jauzā’, or something else.

Between transliterating from one writing system into another, a misreading, and maybe more glitches; by the time the star’s name got to my language it was Betelgeuse.

But we do know what it means: Giant’s Shoulder, or Hand of the Central One, or maybe Armpit of the Central One.

Me? I’ll stick with calling it Betelgeuse.

Now, finally, the usual links:

1 Science, psychology and silliness:

Anonymous(?) French(?) artist's cartoon of a destructive comet. (1857)2 Comets, climate and me:

3 Perspectives and scale:

4 Crab Nebula, a famous supernova remnant:

5 Archaeology, astronomy and palentology:

6 Ancestors and attitudes:

7 Science, mostly:

8 Naming Betelgeuse:

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About Brian H. Gill

I was born in 1951. I'm a husband, father and grandfather. One of the kids graduated from college in December, 2008, and is helping her husband run businesses and raise my granddaughter; another is a cartoonist and artist; #3 daughter is a writer; my son is developing a digital game with #3 and #1 daughters. I'm also a writer and artist.
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