What is the nearest star to Earth that can go supernova?

By Phil Plait | July 14, 2008 9:30 pm

This is a common question: what is the nearest star to the Earth that can explode as a supernova? Most people say Betelgeuse, a red supergiant in Orion, but there are several stars that are closer.

In the video below I answered this question as part of my weekly live video chat.

If you have an astronomy question you want answered, tune in to the live chat, which I usually do on Sundays at 15:00 Mountain time (21:00 UT). I might make a video of your Q&A!

Some notes: the image of Spica is used under the Creative Commons license, and is from fdecomite’s Flickr set. The awesome white dwarf illustration is from my friend the artist David Hardy (and PPARC), who gave me permission to use that in my book, so hopefully he won’t mind if I plug him here.


Comments (50)

  1. How far is the Sirius system? I thought that was a pretty close white dwarf/normal star pair.

  2. I thought it was stars equal to or greater than 8 solar masses that go supernova…

    “White dwarfs are incredibly dense…”
    …like creationists…

  3. Robert

    Sirius A and Sirius B isn’t a contact-binary, wich is required to have a white dwarf explode into a 1a supernova, also Sirius B is estimated to be 120 million years old so my question is how long would it take for an average contact-binary white dwarf to explode into a 1a supernova?

    Also for a normal supernova, the star does not run out of fuel, it has still plenty left, but the core of Iron just becomes to much and crosses the Chandrasekhar limit which results in a gravitational collapse, and there she blows as a galactic mr. Creosote.

  4. I can’t get to Youtube at work but if one of the close ones she goes boom we’re stuck with the cheque, Monsieur yes? Pay the piper? Doomed?

    Neat way of sterilising galactic regions though. Drake’s equation and all that.

  5. Sillysighbean

    A throughly enjoyable video! Now I can sleep at night. whew. My only complaint is this stupid ad they have for Madison Square Garden’s Dinosaur show…it kept “growling” over Phil’s lecture. grrrrrr myself.

  6. C


    Thanks for answering my question in the chat. I read about GRB’s in Wikipedia, and when it said that one 4 light years away could incinerate the earth, I definitely paid attention… and lost a little sleep. Count me in for the book when it comes out.

    Also, this is for the fray: Does anyone remember a gorgeous photo that Phil liked to, showing a huge hurricane from orbit? I’ve got back through the archives and can’t find it. A very striking photo.


  7. pcarini

    So speaking of that book.. when can I get my hands on it?

  8. @Nicole: Said
    “White dwarfs are incredibly dense…”
    …like creationists…

    Well, I think it’s just wonderful that God put us in a place where we don’t have to worry. It’s just such a blessing that Satan can’t use any close stars and play with their nuclear fires and blow us up!
    When I was in High School, way back many years ago, before Pluto got Plutoids, our teachers would use the terms nova and supernova. Is there a difference? Are they 2 separate classes of exploding stars, and if so, what determines which?

  9. Tim G

    Michael L,

    I also seem to recall a different naming convention. A “nova” was different from a “supernova”. A nova was supposed to result from an exploding surface of a white dwarf (Now called Type Ia supernova?) as opposed to a supernova (Now called Type II supernova?), which results from the core collapse of a giant star.

    I have also heard the term “hypernova” which is supposed to be a supernova of stars far bigger than necessary to produce a black hole.

  10. MikeinJapan

    Oh no!! Ejection! So, what are the chances of our minty little world suffering a similar ejectile fate?

  11. andy

    Tim G: novae and type Ia supernovae are two different phenomena: novae are the result of detonation of surface hydrogen/helium accreted onto a white dwarf, and the white dwarf typically survives – leading to recurrent novae. Type Ia supernovae are different and involve fusion of carbon in a white dwarf that approaches the Chandrasekhar limit (above which the white dwarf cannot be supported by electron degeneracy pressure). This destroys the white dwarf.

    Out of interest, when Sirius A goes through its red giant stage, will the expansion be sufficient to start significant mass transfer to Sirius B? What about Procyon?

  12. Tim G

    Thanks, Andy.

  13. Michelle

    I laughed when you showed the white-dwarf-sucks-off-neighbors image… The colors were so similar to your objects that it was totally on target. :)

  14. Just Al

    Am I the only one that suspects that Phil could get his hands on plenty of nice little spheres and such for his models, but chooses slightly eccentric (astronomy joke!) ones on purpose? And are they going to get weirder?

    “Let’s say that that yellow VW over there is our sun, and the Little Astronomer’s head is the Earth. Now, walk around the car in a circle, honey, and spin as you do so. And keep your head tilted 23 degrees. No, 23 degrees. Good. Now, the sun has an axial tilt too, which we can simulate by flattening two of the tires…”

  15. Ray M

    OT: Pareidolia alert!

    Today’s APOD (http://antwrp.gsfc.nasa.gov/apod/astropix.html) clearly shows The Face Of God (upper right) peering down on one of His creations, the Lagoon nebula. He was even nice enough to switch off all the stars so that we could better appreciate his handiwork.

  16. Andy Beaton

    I stopped worrying about what a supernova would do to the earth when I saw a simulation of a black hole floating through the solar system. Now *that* is something worth irrational fear!

  17. Greg

    Not to be too snarky, but there’s no specific time frame in the question. Given any amount of time, wouldn’t the answer be… Sol?

  18. Greg

    Oh, poop. I just watched the video. Never mind.

  19. “It was ejected from my system.”

    Phil, if you want the mint to be ejected from your system, you have to eat it first….

  20. Slightly OT, but I’ve written a piece of electronic music called “Pleiades” that I’ve decided to dedicate to Phil. Details on my website (click my name and select Music Catalogue), and if you want to download it, you can either get it from there, or from alt.binaries.sounds.mp3.avant-garde – share and enjoy!

  21. Gary Ansorge

    AH, Sol, destine to bloat and swell to a red giant stage,,,
    Ah, the vicissitudes of old age,,,

    GAry 7

  22. Ray


    Please write at least some of your response down in the future. My network nazis won’t let the videos play on my company’s network. So I still don’t know which star will be haunting my sleep tonight.

  23. DrFlimmer

    Btw: Phil, Nice bookcover 😉 Hopefully I can buy it here in “old Europe”, too… (maybe amazon must help…)

    @Just Al: Nice idea 😉

  24. Rob

    Wait, we can prevent solar flares? We can prevent asteroid impacts?

    With what technology? How are we even able to predict solar flares (we can’t) to prevent them (again, leaning towards no)?

  25. Rich

    I’ll second the request for a transcript or summary for your video responses. YouTube and just about any video plays haltingly on my 1997 laptop, even on a decent connection. (Yes, I’d simply buy something newer if I could…)

  26. Hmmm, a transcript is a good idea, and has been mentioned before. I can’t do that on my own, but maybe I’ll put a call out for an official BA transcriptionist. It’s not like I am print my own money, but I’ll have to think of something I can do for compensation. Suggestions?

  27. A copy of your book?

  28. Ryan

    I want that book so bad. Amazon.com says it comes out October 16th… arg, too far away. 3 months…

  29. Tim G

    Here’s a transcript of the first quarter of the video. I don’t think the punctuation is perfect.

    So, Phil Plait from BadAstronomy.com and I’m doing my live chat as I’m recording this and I was just asked: what is the nearest supernova candidate to the earth? Now a supernova is a star that explodes and there are two kinds. Stars like the sun cannot explode—they cannot explode…the sun will not explode—got it? Not! Everybody always says “The sun is going to explode!”—no! You need a much more massive star it has to be about twenty or more times the mass of the sun to explode. And after it lives its life out basically the core runs out of fuel and it collapses and it does two things. The outer layers of the star collapse down and they sort of rebound off the core—it sets off sort of a shock wave. Also because of very complicated physical processes neutrinos are created in the core and these are very ghostly particles. They can pass through light-years of lead without even seeing that it’s there but this incoming material gets a lot denser than lead and so it actually absorbs a lot of these neutrinos. A tremendous amount of energy is absorbed by that gas and when you dump a huge amount of energy into matter it basically explodes outwards and that blows the star up. And so that’s one way you can get a star that explodes.

  30. Chip

    Phil – My 81 year old mom wrote to me, (she reads your blog,) and about your talk she said: “Well, that’s a relief! Now I can go back to worrying about asteroids.” 😉

  31. Tim G

    Perhaps transcripts can be collaborative efforts. Videos can be broken down into more manageable parts.

  32. Valdis Kletnieks

    OK, now here’s a slightly different question – I’ve seen *lots* of stuff on the web that talk in great detail about what happens to the white dwarf partner in the binary system when it goes Type Ia Supernova.

    But I haven’t found *anything* about what the likely fate of the *other* star is…

    Anybody got a pointer on that one?

  33. @Phil: Thank you for this blog entry, BUT… Supernovae Type Ia (the white dwarf thing) happen when the white dwarf accumulates enough mass to cross the Chandrasekhar-limit, which is about ~1.4 solar masses: only then the white dwarf will collapse under its own mass (finally overcoming electron degeneracy pressure) and/or ignite the carbon-fusion at its center and explode.

    The accumulation of unburnt hydrogen stolen from the red giant companion and the subsequent thermonuclear reactions on the surface of the white dwarf exist though: they are called nova events: very bright, but no supernova, no big explosion that destroys the star.

    But the ashes of these events (the fusion products) accumulate on the surface and, over time, steadily push the white dwarf a little further towards the ~1.4 solar masses limit mentioned above.

    So it’s nova-nova-nova-… …-nova-SUPERNOVA!

  34. Bynaus, I was simplifying in the video. But it’s more complicated than you say as well; there are many kinds of Type I events. As another example, a helium-capped CO white dwarf can detonate with a subsonic wave of fusion over its surface, and triggered by the event the star itself completely explodes.

  35. Would it be possible, on these video answer blog posts, to add a transcript or at least the answer to the post? I am at work and cannot watch videos (the sound goes through the whole restaurant).


  36. AJWM

    A variation on the question: what’s the nearest star (or stars) that might go supernova anytime soon, like within the next couple of thousand years? Anything nearby (for sub kiloparsec values of “nearby”)?

    What about hypernovas? I know Eta Carinae underwent a “false supernova” event circa 1843, and is expected to blow Real Soon Now, but that’s something over 7500 ly away. Anything else whose size/distance value gives an equivalent (or greater) threat? Thanks.

  37. amphiox

    Question 1: What would it look like if Spica or any of the other close (inside 500ly, say) stars went supernova? Are we talking brighter than full moon here? Could it be possible to be brighter than daytime sun? How useful would such an event be for astronomers, compared to more distant supernovae?

    Question 2: White dwarfs last for very long periods of time, right, as in trillions of years? Given long enough periods of time, would it at all be possible for Sol to become a contact binary, ie by being captured/capturing another star on a random close approach?

  38. gregg

    There is a cool web-site “3DGalaxcyMap.com where you can navigate through our local Orion Arm of the Milky Way. In an adjacient sector (-1,-1,0) is a super giant star over 8 solar masses that looks to close for comfort in my humble opinion. Given that the “Great Attractor” is reeling in the Milky Way at over 200 kilo meters per second, and the Shapley Super Structure is reeling in the Great Attractor at over 700 km/s, shouldn’t mankind build a really fast spaceship and escape in the other direction? What is the best escape route? Will stars explode before we reach them blocking our way with debris, or explode when we are close to them? Should we space surf towards distant nebula hoping for new safe stars upon arrival?

  39. mm

    Recently, Betelgeuse is producing shock wave which seems to close of its death.
    Isn’t it?

  40. Punas

    Hi Phil, is any chance that Earth in the past was affected by any supernova? i heard somewhere that in Jurrasic Period Earth could have been affected by gama radiation from a supernova (is that true?)

  41. Hmm. The Sun will not go supernova, it’s not massive enough. Sirius has a white dwarf companion, but they’re not close enough to each other. One wonders if a closer white dwarf around a nearby star could have been missed.

    Given a long enough time frame, one supposes that the Sun could wander into a stellar nursery just as brand new big stars form…

    But there are lots of dangers. We don’t have to invent new ones.

  42. What about IK Pegasi B?

    Also – is there any guess as to when Spica might go supernova? Is it (astronomically) imminent, like I understand Betelgeuse to be? (Or, more generally, which of the nearer candidates is likely to go first?)

  43. Mike Torr

    Thank you for the Ferris B reference :) Some of us got it!

  44. John

    I’m sure this can’t be predicted with any great accuracy but I’m curious to know when the next supernovae will occur that we will be able to see in the night sky?

  45. Sirius is only 8 light years away. It is an A type star and so it will do the firework, but not for millions of years.
    Gaminga (spelling?) could have been less that 50 light years away when it went supernova just over 300,000 years ago. A star less than 30 light years away would destroy Earth’s ozone layer. 1 light year away would leave us a lifeless as a crater on the Moon.
    Betelgeuse is fairly near, not to be of any danger but could go supernova tomorrow, or in a thousand years time.

  46. On the subject of whether Spica will go supernova, or rather when. We have a while to wait. It’s still in its main sequence stage. You want to look at the M class super giants, Betelgeuse, Mu Cephei, Antares. They’re all candidates but I think Betelgeuse is your best bet and will the the brightest one, at least for 1/3 of a million years.

  47. abadidea

    Nicole #2: as an ex-creationist, I feel the need to defend my younger self as not incredibly dense, but incredibly sheltered and indoctrinated.

  48. Benjamin

    You say 50 light-years. How about a star like WR-104? How far must we be from a supernova seen from one of its poles to be safe?

  49. WR-104 is one of a few really big stars that might produce a gamma ray burst. Such a burst would come from the pole of the star. And for awhile, it was thought that WR-104 had a pole pointed right at us. There is now evidence that the pole must be at something like 40 degrees. WR-104 is about 8000 light years away. Some estimates suggest a distance of about 5000 light years is safe, even pole-on.

  50. SS

    That was a great video, simple enough for my 12 year old with an overactive imagination to understand but not patronising. You’ve calmed his nerves. Thank you. Off to check out your book on Amazon now…


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