… is it possible it already blew up?
Yes.
It could have blown up yesterday, but no way to tell until 700 years from now.
Or it could have blown up 699 years and 11 months ago, and we’ll find out next month.
(Taking the 700 light—years as a hard number, for the purposes of this discussion )
Side note: The title for “Beetlejuice” is a play on the character Betelgeuse’s name, which in turn based on the Betelgeuse star, which is housed in the infinite blackness of space but in the same constellation as the more famous star Orion.
And the character’s name is spelled like the star multiple times in the movie. The movie is named Beetlejuice, but ghost originally spelled his name “Betelgeuse.” Seeing that when I rewatched it recently felt like a Mandela effect moment.
:dubious:
Orion is AFAIK the name of the constellation, that includes the stars: Betelgeuse, Rigel, Bellatrix, Mintaka, Alnilam, Alnitak, Saiph, Meissa.
And Betelgeuse is, by a good margin, the most famous star in that constellation (and occasionally the brightest, though it’s usually in second place).
Why the most famous? I’ve heard about Rigel at least as much. It is usually the brightest star in Orion and IRC, in the top 10 for brightest stars (for Earth).
Rigel comes up in the Old Man and the Sea. Tregonsee is a Rigellian in the Lensman series and one of the few Stage 2 Lensmen. Rigel comes up often in Star Trek.
Yeah, that’s funny - Betelgeuse is also called Alpha Orionis, meaning the brightest star in the constellation Orion. Or shortened to Alpha Ori. Rigel is called Beta Ori (ironically enough). Rigel more often is brighter to us than Betelgeuse, tho.
Rigel is a king hell impressive star, just fantastically powerful. So is Deneb. As stars go they are very far from Earth, to still look bright in our sky. When you’re looking at either of them, you’re looking past zillions of noisy little stars in the foreground, and reaching way out beyond them.
Now, the custom in astronomy is usually to set aside the fact that something is so many lightyears away, for the purpose of past present and future tense. There are exceptions, such as, if you’re looking at a quasar back near the beginning of the universe, then, yes, you do say stuff like “this is what the universe looked like when it was young.” But customarily you would say “Betelgeuse could blow up any day now” and not complicate the conversation with an accounting of the light travel time (unless for some special reason that’s the focus of the conversation). There’s no way we could be influenced by a supernova or any other event, if at the velocity c the fact of its occurrence could not have reached us yet.
Huh, OK, Rigel actually gets more Google hits than Betelgeuse (10.2 million to 9.3 million). I’ll concede the point.
The Bayer designations for stars was not always that the brightest would be alpha, second brightest beta, etc. It was just roughly done that way. At the time they were assigned, there was no precision measurement of stellar brightness, so even if they tried, there would have been some constellations with it wrong. As it is, there’s some 30 constellations where the alpha star is not the brightest.
Betelgeuse is more famous because of the movie. It’s shouldering the responsibililty of being the best known star in the constellation quite well. But Rigel has its foot in the door, so to speak. It’s not pussy-footing around in the fame game.
I’m pretty sure that it was Tregonsee that put Rigel over the top. 
Away with you! 
Betelgeuse is the armpit of Orion.
We can say, “Any day now, Earthlings could see Betelgeuse go ker-blooey.” Just when it DID discorporate doesn’t matter to us self-centered Terrans. We see something now and it’s new to us. That’s all a “stella nova” is - a new star to our eyes. Every glance skyward is a look into the far distant past.
I suspect that the Sun is the most famous
(bolding mine)
The Sun is never in Orion.
Actually if ALL of them blew up we wouldn’t know it until at least 4 years had passed.
Although, if alpha Centauri as we see it right now is what a star looks like a mere four years before it blows up, then our understanding of stellar physics is completely and spectacularly wrong.
For Betelgeuse, under our current understanding of physics, there’s a reasonable chance that it’s already blown. And there might be two or three other stars visible in the night sky for which that’s true. But not for the vast majority of them.