# Betelgeuse - supernova - dumb question **URL:** \ **Category:** Factual Questions\ **Created:** [June 8, 2012, 1:47am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453 "2012-06-08T01:47:05Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![HazelNutCoffee](https://avatars.discourse-cdn.com/v4/letter/h/ac91a4/32.png) [@HazelNutCoffee](https://boards.straightdope.com/u/HazelNutCoffee)\ **Post date:** [June 8, 2012, 1:47am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/1 "2012-06-08T01:47:05Z")
Some of my friends have been posting on Facebook about the “imminent” implosion of Betelgeuse - supposed to happen in 2012 (although most credible articles I’ve read say that no one knows exactly when the supernova will happen). Here’s my dumb question - Betelgeuse is 640 light years away. So that means even if a supernova does happen, we won’t see it until 640 years after it happens . . . right? So this supernova could have already happened? I may be asking a very obvious question, but none of the articles I’ve read address this question at all. ---
**Author:** ![zombywoof](https://avatars.discourse-cdn.com/v4/letter/z/9e8a1a/32.png) [@zombywoof](https://boards.straightdope.com/u/zombywoof)\ **Post date:** [June 8, 2012, 1:52am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/2 "2012-06-08T01:52:46Z")
Right, the speed of light is an absolute limit, you’re always seeing light emitted 640 years ago. So sure, it could have happened yesterday but we won’t know it for 640 years - but forget any nonsense about it being “supposed to” go supernova in 2012, scientific predictions on when it might happen are on the order of any time in the next million years. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [June 8, 2012, 2:28am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/3 "2012-06-08T02:28:31Z")
The predictions I’ve heard are much more imminent: We’d see it any time in the next thousand years or so. Which means it’s quite plausible that it might have already gone and we’re just waiting to get the news. Incidentally, it’s the only star visible to the naked eye for which this is plausible. Also note that, while a Betelgeuse supernova _would_ look really freakin’ impressive, it would _not_ be an end-of-the-world scenario (and probably wouldn’t have any real disastrous effects at all-- Worst case, it might cause eye damage if you stared directly at it, like the Sun). So tell your friend not to bother trying to tie it to the whole Mayan thing. ---
**Author:** ![Anne\_Neville](https://avatars.discourse-cdn.com/v4/letter/a/b9e5f3/32.png) [@Anne\_Neville](https://boards.straightdope.com/u/Anne_Neville)\ **Post date:** [June 8, 2012, 2:37am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/4 "2012-06-08T02:37:55Z")
> [@HazelNutCoffee](#): > > Some of my friends have been posting on Facebook about the “imminent” implosion of Betelgeuse - supposed to happen in 2012 (although most credible articles I’ve read say that no one knows exactly when the supernova will happen). No credible astronomer thinks we can predict when Betelgeuse will go supernova down to the year. > [@](#): > > Here’s my dumb question - Betelgeuse is 640 light years away. So that means even if a supernova does happen, we won’t see it until 640 years after it happens . . . right? So this supernova could have already happened? I may be asking a very obvious question, but none of the articles I’ve read address this question at all. Yes, Betelgeuse could have already gone supernova, and we just don’t know about it yet. We will not know until 640 years after the supernova actually happens. ---
**Author:** ![Saint\_Cad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saint_cad/32/18907_2.png) [@Saint\_Cad](https://boards.straightdope.com/u/Saint_Cad)\ **Post date:** [June 8, 2012, 2:47am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/5 "2012-06-08T02:47:20Z")
What if someone saw it explode 640 years ago and sent us a message? Then they could have told us that we would see it in 2012. yes it is a woosh ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [June 8, 2012, 3:15am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/6 "2012-06-08T03:15:07Z")
As an aside, I can’t decide whether if the awesomeness of seeing Betelgeuse go supernova in my lifetime would be worth Orion looking “wrong” every time I saw it afterwards. ---
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [June 8, 2012, 3:26am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/7 "2012-06-08T03:26:39Z")
So, uh, what would it look like? Bright as the sun? Some weird colour? How long would it last? ---
**Author:** ![Grateful-UnDead](https://avatars.discourse-cdn.com/v4/letter/g/ccd318/32.png) [@Grateful-UnDead](https://boards.straightdope.com/u/Grateful-UnDead)\ **Post date:** [June 8, 2012, 3:32am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/8 "2012-06-08T03:32:31Z")
> [@pravnik](#): > > As an aside, I can’t decide whether if the awesomeness of seeing Betelgeuse go supernova in my lifetime would be worth Orion looking “wrong” every time I saw it afterwards. Maybe it would not be much of an issue. I read recently (no cite) that a supernova in our galaxy would produce enough radiation to sterilize planet earth. Also, the extinction of the dinosaurs may not have been due to meteor hit, but was actually caused by a supernova. So, if this is true (an I admit I don’t have a clue), then put on your dark glasses and enjoy the thirty seconds or so that you will be alive to enjoy the show. ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [June 8, 2012, 3:48am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/9 "2012-06-08T03:48:42Z")
Nah, there have been supernovae in our galaxy during human history. The [Crab Nebula](http://en.wikipedia.org/wiki/Crab_Nebula) is the remnant of a star in Taurus that went supernova in 1054. Chinese astronomers saw it and called it the “guest star,” and it was supposedly pretty spectacular, bright enough to see even in daylight. There was an even brighter one in [1006](http://en.wikipedia.org/wiki/SN_1006). ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [June 8, 2012, 3:54am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/10 "2012-06-08T03:54:57Z")
Nifty wikipedia article: [History of supernova observation](http://en.wikipedia.org/wiki/History_of_supernova_observation) ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [June 8, 2012, 4:46am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/11 "2012-06-08T04:46:18Z")
> [@pravnik](#): > > As an aside, I can’t decide whether if the awesomeness of seeing Betelgeuse go supernova in my lifetime would be worth Orion looking “wrong” every time I saw it afterwards. According to estimates described [here](http://http://en.wikipedia.org/wiki/Betelgeuse#Approaching_supernova) of its maximum brightness in such an event, I doubt if you’d be able to see the rest of Orion, or any other stars at all with the exception of the Sun. The full moon is bad enough at washing out most of the sky, even in areas with a dark sky, and the Betelgeuse supernova will be brighter still. But it would only be for a few months in any event. ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [June 8, 2012, 5:06am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/12 "2012-06-08T05:06:04Z")
> [@Spectre\_of\_Pithecanthropus](#): > > According to estimates described [here](http://http://en.wikipedia.org/wiki/Betelgeuse#Approaching_supernova) of its maximum brightness in such an event, I doubt if you’d be able to see the rest of Orion, or any other stars at all with the exception of the Sun. The full moon is bad enough at washing out most of the sky, even in areas with a dark sky, and the Betelgeuse supernova will be brighter still. But it would only be for a few months in any event. Link no work. 😉 By Orion looking “wrong” I don’t mean so much during the supernova, I mean forever missing a star after the supernova dims - missing a shoulder, so to speak. I don’t know, though, sounds pretty awesome. ---
**Author:** ![Der\_Trihs](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/der_trihs/32/233_2.png) [@Der\_Trihs](https://boards.straightdope.com/u/Der_Trihs)\ **Post date:** [June 8, 2012, 5:08am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/13 "2012-06-08T05:08:11Z")
> [@pravnik](#): > > Link no work. 😉 [Try this.](http://en.wikipedia.org/wiki/Betelgeuse#Approaching_supernova) ---
**Author:** ![HazelNutCoffee](https://avatars.discourse-cdn.com/v4/letter/h/ac91a4/32.png) [@HazelNutCoffee](https://boards.straightdope.com/u/HazelNutCoffee)\ **Post date:** [June 8, 2012, 5:10am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/14 "2012-06-08T05:10:37Z")
Thanks for the clarification guys. 🙂 ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [June 8, 2012, 5:12am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/15 "2012-06-08T05:12:08Z")
> [@Der\_Trihs](#): > > [Try this.](http://en.wikipedia.org/wiki/Betelgeuse#Approaching_supernova) Thanks for the quick revision. ---
**Author:** ![artemis](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@artemis](https://boards.straightdope.com/u/artemis)\ **Post date:** [June 8, 2012, 5:17am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/16 "2012-06-08T05:17:25Z")
> [@Chronos](#): > > The predictions I’ve heard are much more imminent: We’d see it any time in the next thousand years or so. Which means it’s quite plausible that it might have already gone and we’re just waiting to get the news. Incidentally, it’s the only star visible to the naked eye for which this is plausible. In the Northern Hemisphere sky, yes But isn’t Canopus as likely (or perhaps even more likely) an imminent supernova candidate as Betelgeuse? ---
**Author:** ![Grateful-UnDead](https://avatars.discourse-cdn.com/v4/letter/g/ccd318/32.png) [@Grateful-UnDead](https://boards.straightdope.com/u/Grateful-UnDead)\ **Post date:** [June 8, 2012, 5:32am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/17 "2012-06-08T05:32:19Z")
> [@pravnik](#): > > Nah, there have been supernovae in our galaxy during human history. The [Crab Nebula](http://en.wikipedia.org/wiki/Crab_Nebula) is the remnant of a star in Taurus that went supernova in 1054. Chinese astronomers saw it and called it the “guest star,” and it was supposedly pretty spectacular, bright enough to see even in daylight. There was an even brighter one in [1006](http://en.wikipedia.org/wiki/SN_1006). Damn! I hate it when somebody ruins a good story with facts. ---
**Author:** ![Koxinga](https://avatars.discourse-cdn.com/v4/letter/k/4af34b/32.png) [@Koxinga](https://boards.straightdope.com/u/Koxinga)\ **Post date:** [June 8, 2012, 5:48am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/18 "2012-06-08T05:48:10Z")
I thought the bad stuff would happen if one of the star’s poles was pointing directly at us. Is that the case with Betelgeuse? ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [June 8, 2012, 5:59am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/19 "2012-06-08T05:59:45Z")
> [@pravnik](#): > > Link no work. 😉 By Orion looking “wrong” I don’t mean so much during the supernova, I mean forever missing a star after the supernova dims - missing a shoulder, so to speak. I don’t know, though, sounds pretty awesome. And Ford Prefect in _The Hitchhiker’s Guide to the Galaxy_ would have a rather tragic backstory. ---
**Author:** ![buddha\_david](https://avatars.discourse-cdn.com/v4/letter/b/ee7513/32.png) [@buddha\_david](https://boards.straightdope.com/u/buddha_david)\ **Post date:** [June 8, 2012, 6:34am UTC](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453/20 "2012-06-08T06:34:13Z")
> [@Koxinga](#): > > I thought the bad stuff would happen if one of the star’s poles was pointing directly at us. Is that the case with Betelgeuse? Yes, a [gamma-ray burst](http://en.wikipedia.org/wiki/Gamma_ray_burst#Rates_and_potential_effects_on_life_on_Earth) from a nearby star would be extremely nasty, though it probably wouldn’t instantly sterilize the planet like some doomsayers are claiming. However, gamma ray bursts only occur in a very narrow stream (from the poles of the star) and Betelgeuse isn’t pointing at us in any way for the gamma rays to affect us. [Next page](https://boards.straightdope.com/t/betelgeuse-supernova-dumb-question/624453.md?page=2)