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What is Betelgeuse, the Star?

Betelgeuse is a unique celestial object. It’s classified as a “red supergiant”—one of the most massive stars in the night sky, which appears orange-red in color. Betelgeuse is nearing the end of its life (stars expand as they age). In fact, it’s considered the most likely star in the night sky to go supernova—and explode. 

As seen from Earth, Betelgeuse marks the left shoulder of Orion. We’ll get into viewing tips later. First, let’s talk about its unusual name and the various odd pronunciations, which are merely starting points for arguably the most dangerous and extreme of all the night’s inhabitants.

The Story of Betelgeuse’s Name

It’s that peculiar name that starts everything going. In the original 1988 movie, the credits listed the lead character, played by Michael Keaton, as “Betelgeuse” in some places (matching the celestial object’s spelling) and “Beetlejuice or Beetle Juice” in others (corresponding to the main character). But long before any film was written and shot, many struggled with the star’s pronunciation; it was never unusual to hear “Beetle juice” from celestial beginners.

Those trying to ferret out the origins of that odd name found only confusion in standard references. If you look it up, you’ll get completely different meanings for Betelgeuse. 

• The Random House college dictionary claims it means “Shoulder of the Giant.” 
• Webster’s New World dictionary says Betelgeuse means “House of the Twins.” 
• Wikipedia states the name means “Hand of the Central One.” Everyone says something else.

You’d think the published books on “Star Names” would settle the matter. But experienced astronomers and journalists long ago found an obscure, accurate source for deciphering cryptic star titles. It’s really a story of its own. 

Eighty years ago, a serious amateur astronomer who was also an attorney and an Arabic language scholar traveled to Middle Eastern countries to pore through original sources to uncover the true meaning of various stars whose names were coined thousands of years ago—and also to determine how regional pronunciations changed during the intervening centuries. After all, two-thirds of all the star names were created by that region’s desert-dwellers, and they still populate every official astronomy chart.  

This remarkable man, George A. Davis, Jr, with the help of libraries in Buffalo and those at Cornell, Harvard, and Princeton universities, produced a 23-page paper entitled “Pronunciations, Derivations, and Meanings of a Selected List of Star Names,” which was published in the 1940’s in a now-defunct astronomy magazine. Reprinted by Sky Publishing corporation in 1971, its yellowing pages remain a precious possession of your ��������’s astronomy editor. And here’s some very good news. They’ve made it available for free online. Trust me: This will be your go-to source whenever you wonder how a particular star got its name, or what it means, or how you should pronounce it.

When it comes to Betelgeuse, the bright reddish star that marks Orion’s left shoulder, Davis discovered its name was incredibly old. He found it was originally Ibt Al-Jauza long before the Arabs began their star-naming, and it incredibly dates all the way to the ancient Sumerians. Back then, the prominent winter star pattern was not seen as a hunter but as a sheep. And the name literally means “Armpit of the Sheep.” This makes it a candidate for the least glamorous name in the galaxy. 

How to Pronounce Betelgeuse

Davis also showed why it should be pronounced like astronomers do – as BET’l’j�Ǵdz�. You can probably “bet” on that and shouldn’t buy into the image of “juice” emanating from an insect you accidentally stepped on. In any case, it’s clear that Tim Burton and the makers of the new movie version took no chances and simply changed the spelling to only allow for their preferred humorous pronunciation.

One of the Largest Stars in the Sky

But there’s nothing humorous about the actual star. It’s seriously imposing and famously one of the very largest in the entire sky. It’s so massive that telescopes on Earth can even discern its surface.

Just visualizing its enormity is fun all by itself. My favorite model, which I created during my college days, is that if Betelgeuse was denoted by an enormous orange ball standing as high as a ten-story building, then our planet Earth could be represented by the period at the end of this sentence.

Only one of all the night’s bright stars gives it any competition. The red supergiant Antares marking the heart of Scorpius the Scorpion is a pretty good Betelgeuse look-alike, and each has a fan club believing their star is the record-holding biggest of all. What prevents settling the competition is distance. 

How Far Away Is Betelgeuse From Earth

Both red supergiants, Betelgeuse and Antares, are somewhere around 400 to 700 light-years away, which is too far for actual parallax measurements using direct trigonometry. Every few years, researchers manage to somewhat refine the distance to one or the other, and then a new “biggest star” is announced to howls of predictable protest, only to have the process reverse itself a few years later.

A bigger issue is that Betelgeuse is not just huge but also heavy. It weighs 10 to 20 times more than our Sun, and such stars explode into supernovas in their old age. Well, Betelgeuse is indeed in its old age. When it dies, it will go supernova. 

What is a Supernova?

A supernova is a massive explosion that raises the star’s brilliance—typically 100 million times brighter than before—so that it often outshines the combined light of all the billions of stars in its entire galaxy. The event is catastrophic for everything in its neighborhood. 

But here’s where we got lucky. Since Betelgeuse is up to 700 light years away, its eventual supernova will not endanger life on Earth. Nonetheless, its supernova would send a concentrated blast of particles and radiation, which would increase Earthly mutations and alter our planet’s life for centuries to come.

Visually, meanwhile, it would grow so intensely brilliant it might not be easy or safe to look at. Certainly its dazzle would create nightly shadows whenever it was up, and even turn the night sky a dark blue during the year it retained its initial brilliance.

When to See Betelgeuse

Its strange name, pronunciation, danger, superlative size—we hardly needed a movie to make even casual sky-observers want to check it out for themselves. 

But if you do need tips to find it, it’s easiest to catch at this time of year (near early autumn) when it’s rising. Then, it’s the only reddish star low in the east and precisely left of the prominent vertical line of three stars that forms Orion’s famous belt. (I say vertical because when the Hunter rises, he starts out in a prone orientation.)  

• In late September, Betelgeuse rises around 1 AM. 
• But it rises two hours earlier per month, so it’s low in the east at 11 PM on Halloween. 
• It’s there at a more convenient 9 PM on Thanksgiving. 
• With Daylight Time over, it’s up at 6 PM by Christmas and the solstice and out all night. 
• It remains dominant through the end of April.

When Will Betelgeuse Explode?

Observers have had a lot of fun with Betelgeuse in recent years. We’ve always been aware its brightness slowly changes, with a small irregular alteration over the course of three years. This is when the huge star temporarily swells up and grows even larger like an inflating balloon, an internal instability that will someday get out of hand and cause its complete destruction.

In early 2000, its brightness drastically changed. While we stared in disbelief, Betelgeuse lost half its light! Suddenly, it no longer dominated the upper portion of the Hunter’s body; it merely matched its other shoulder, which was marked by the non-eye-catching (2nd magnitude) star Bellatrix. Everyone had the same thought: Does this dramatic change mean something is unfolding inside the star? Is the supernova now imminent?

But 2000 came and went, with Betelgeuse recovering from appearing unusually dim and back to its usual self. Astronomers resumed their habitual shrugging. Yes, it’s still expected to explode in a spectacular supernova. But the star could “go supernova” tomorrow or not for another 10,000 years. 

Using a backyard telescope doesn’t help settle anything. Unlike most of our galaxy’s members, Betelgeuse isn’t a double star nor belongs to a multiple-star system, so there’s nothing to see but a bright, companionless orange dot. 

It doesn’t sit inside a nebula because it’s not a newborn. Nor is it emitting a gassy ring like some other old stars. In fact, the absence of any nebulosity around Betelgeuse is a helpful part of its story.

The image of a single reddish star surrounded by nothing is at the same time reassuring and perilous, like a ticking time bomb. Reassuring because it’s still intact. Dangerous because this will change, big time—and we won’t know until it happens. So we watch and wait. 

Perhaps we could kill some time by seeing the movie.