Youngest galactic supernova (not aliens) found

By Phil Plait | May 14, 2008 11:00 am

If you’re wondering what all the buzz has been about the past few days over a NASA discovery, then wait no longer. No, it’s not aliens or an incoming asteroid. Instead, it’s still very cool: astronomers have found the youngest supernova in the Milky Way.

First, before I explain, here’s the photo of the newest galactic family member:

It kind of looks like a baby head swaddled in a blanket. Or a really bad drawing of Caesar. Anyway, seriously, this is a big deal. Why?

When a star like the Sun dies, it blows off a lot of its outer layers, leaving behind a dense hot object called a white dwarf (FYI, I have a more detailed description of all this here). If the star is binary — it has a companion — then the immense gravity of the white dwarf can draw material off its mate, and that matter will pile up on the surface of the dwarf. If enough piles up at just the right rate, it can ignite in a thermonuclear fire. This sets off a chain reaction, and the entire star self-destructs. This creates an immense amount of energy — as much energy is released every second as the Sun emits for billions of years — and an octillion tons of gas is launched violently into space at a large fraction of the speed of light.

The event is so titanic that it can be seen clear across the Universe, and of course you don’t want one to happen too close*. But somewhat close is good: we can study them better.

We know how many stars like this there are in our galaxy (as well as massive stars which can also explode, although using a different mechanism), and we know roughly how long they live, so we should be able to predict how often one should go off. The answer is, about three per century, more or less.

But observationally, it’s been more less than more. That is, the last one we know of that blew up in the galaxy was over 400 years ago. That’s been a major pain for astronomers; statistically speaking, it’s a little weird that we haven’t seen one since the 1600s.

But that’s changed. After searching for literally decades, astronomers have found a supernova in our galaxy! It’s official name is G1.9+0.3, which doesn’t exactly make your heart sing, I know. But it’s very cool. It’s a remnant, the expanding gaseous debris from a supernova blast. It’s located very near the center of the galaxy, about 28,000 light years away, and it’s only at most about 140 years old.

The false-color image above shows the remnant as seen by the orbiting Chandra X-Ray Observatory, and the ground-based Very Large (radio) Array in New Mexico. To give you a sense of scale, the object is about 13 light years across, or 80 trillion miles end-to-end. The orange crinkly stuff is extremely hot — millions of degrees hot — X-ray emitting gas, generated by vast magnetic fields in the gas. The bluer material is smoother radio wave emission also dominated by magnetic forces.

Together, they paint an interesting picture of this explosion. For one thing, it looks like a ring, or a smoke bubble. That’s a clear sign that it’s actually a shell of material, and not a solid sphere. A filled sphere of gas would be brightest in the middle and fainter near the edges (because we’re seeing more bright material when we look through the center of a sphere as opposed to near the edge), but a shell has the opposite behavior.

For another, it’s asymmetric: the gas is not expanding in a perfect sphere. Either it’s slamming into gas that existed outside the star before it blew up, or the explosion wasn’t perfectly spherical. That tells astronomers quite a bit about the physics of the explosion mechanism.

How do we know it’s young? Ah, an excellent question! I love this part: we’ve seen this sucker expand!

Here are two radio images of the remnant taken 23 years apart:

See how it’s gotten bigger over time? By measuring that expansion and knowing the time elapsed between the two pictures, we can extrapolate backwards to see how old the object is. If you do the math, all that gas was in one point about 140 +/- 30 years ago. That’s actually an upper limit to the age: it may have been less than that, if the expansion is slowing over time due to the material slamming into gas floating in space. That’s likely; that region of the galaxy is pretty thick with dust and gas.

In other words, this thing went off around the time of the American Civil War.

So that’s how we know it’s the youngest we’ve ever seen. But there’s more! We know the distance to the remnant as well. The amount of dust and gas between us and it can be measured and compared to known maps of the galaxy, kind of like knowing how far away distant mountains are by the amount of haziness you see between you and them. Combining the distance with the expansion measured means we can get a real velocity for the gas, and it’s a whopper: 14,000 kilometers per second, or 5% the speed of light! That’s fast. The amount of energy released in a supernova is numbing.

So you may also ask, why didn’t anyone see this thing when it went off? All things being equal, at that distance it should have been as bright as Venus in our skies, visible even in daylight! But all things are not equal: all the gas and dust between us and it absorb visible light, making this object almost totally invisible. It might have been visible to someone using a good telescope a century or more ago when the explosion took place, but that astronomer would have had to have been looking at just the right spot, and noticed a very faint star that wasn’t there a few weeks before — and this object sits in a part of the sky loaded with faint stars. It would be like noticing a new grain of sand on the beach. Unlikely, and in fact no one did notice.

It can be seen now because we have more advanced instruments these days. X-rays and radio waves are not as affected by intervening glop in the galaxy, and pass right on through. That’s why we can see it at all; even in big optical telescopes G1.9+0.3 is totally invisible.

So there you go. This object will be heavily studied now, I’m sure, because it’s the youngest such explosion we can see up close. It may help us understand how white dwarfs explode, and what the environment is like near the center of the galaxy, and how gas behaves when it violently expands in such a place.

And, well, it’s just cool. It’s been a mystery for a long time why we haven’t seen any young remnants — we expect there to be 60 of them younger than 2000 years, but only 10 are known — and now that we’ve seen this one we know they’re out there, but really just a pain to detect. You can bet that astronomers will look even harder for more of them now that we know they exist.

*Why not? you ask. Ah, because if it’s closer than about 20 or 30 light years it can destroy our ozone layer and do serious damage to us. I have more than you ever want to know about that in gory detail in my upcoming book, Death from the Skies!, which will be out in October.


Comments (134)

  1. Mohamed


  2. madge

    The suspense is over and this is VERY cool. (plus you beat Chris Lintott to the announcement! Phil 1 Chris 0) Glad it is where it is and not closer to us. YIKES!

  3. BMcP

    .In other words, this thing went off around the time of the American Civil War.

    You mean the light from the initial explosion got here around the time of the Civil War, the explosion happened some 28,000 years ago 😉

    Unless you don’t think the universe is that old >:}

  4. Nat

    Wow BA, thanks for the detailed analysis of this news. This news was only released about 5 minutes ago- you must’ve gotten an early heads-up. 😉

  5. BradB

    Thanks! you are my hero right now. I was trying to listen to the live stream from NASA and the internet connection here wasn’t terribly accommodating. It is always a pleasure to read your blog.

  6. Rob P.

    Isn’t it 28,140 years old? So the thing became visible around the time of the American Civil War, but it went off some time in the Upper Paleolithic.

  7. logicboy

    Thanks BA!! I’m glad it wasn’t invading aliens because I just ran out of aluminum foil.

  8. Rhannmah

    It would be interesting to take note that this is a Type 1a(or Ia) Supernova, which are used as standard candles to evaluate distance to other galaxies, since type 1a’s always give off the same amount of light. Incidentally, this is also one of the reasons this discovery is so important, it will allow us to study the phenomenon in its early stages.

  9. Well, they’ll have to keep searching for the Nostromo I guess.

  10. Alfredo Louro

    I don’t understand. If it is 28,000 light years away, how could it have exploded at the time of the American Civil War?

    And am I right in understanding that it was discovered in 1985? The new element seems to be that we now have a second image that allows us to calculate the expansion speed. Or am I misunderstanding this?

  11. Bill Rehm

    Who was the crazy guy on the call? He’s the guy who asked if this would make the moon crickets go away. The speaker said “I’m sorry, pop culture references are lost on me.” Very graceful way of saying “What the hell are you talking about.” He also asked what this had to do with the Swoogie Super Nova of 2007, at which point he was kicked off.

  12. Timothy

    “Isn’t it 28,140 years old? So the thing became visible around the time of the American Civil War, but it went off some time in the Upper Paleolithic.”

    Yes, but it’s convention to use Earth observed time when speaking colloquially to make comparison with similar events. Unless the local time in the neighborhood of the event is important versus Earth-arrival time, or the meaning would be misunderstood, it’s simply easier to use the convention.

    It’s the same as one would say “I am travelling 60 MPH” rather than “I am travelling 60 MPH with respect to the local ground based frame of reference, plus the velocity imparted by the rotation rate of the Earth, plus its velocity around the Sun, plus the Sun’s proper motion …” when the fiddly little details are absolutely correct but irrelevant to the discussion at hand.

  13. It’s seriously cool stuff.

    I note the second caller during questions at the teleconference was a prank one, space crickets to the moon eh?

  14. Aleksandar

    I really hoped it was going to be a direct observation of a central galactic black hole or something related to that. Or two neutrons merging, or black holes merging. Something really interesting. This one is kinda nice but its simply nowhere near the buzz NASA created.

    OTOH discovery that Mira was speeding across the sky was interesting. Not revolutionary but definitely more interesting than a 28,140 y.o supernova.

  15. pelé

    q merda hein…qm for viado entaum fala em ingles!

  16. I always get comments like this when I talk about time and distant objects. I really need to post a FAQ on this!

    Basically, the ultimate speed limit is light speed. That’s not arbitrary, it’s written into the fabric of spacetime. We cannot get any info from a distant object any faster than that.

    Time itself is related to the speed of light, and in a very real sense you can interpret what we see happening in distant space as happening “now”. So when I say the supernova blew up 140 years ago, that’s really a fine way to think of it.

    Think of it this way: we literally cannot know what’s happening “now” at that distance; we have to wait 28,000 years to find out. In point of fact, there is no “now” at that distance, according to the equations of relativity. Now is simply now, and that means that what we see happening through our telescopes is happening now.

    I need to do more research on this idea so I can make it clearer. But honestly, saying it happened 140 years ago is OK. :-)

  17. SarahE

    @ Sam D

    The same guy came in at the very end of the telecon, asking about (if I heard correctly) newly discovered “space vaginas”. Where do these people come from??

  18. MarkH

    Not to get all nitpicky on an astronomer, Phil, but it’s *not* okay to say that it happened 140 years ago, becuase it didn’t. It happened ~140 + its distance from us years ago. If you’re just trying to make it easier for a laymen to comprehend, then why not just say it happened ~28,000 + ~140 years ago, and the light from the event has taken that long to get here? Because that isn’t very difficult to comprehend at all, and I pride myself on being quite the layman. :-)

  19. Julia

    Bill Rehm and Sam D:
    If you do a quick google search for “moon crickets” like I did out of curiosity, you’ll find that whack-job was even more reprehensible.

    NASA needs more funding, if only to get a call screener.

  20. It’s the Firefox web browser logo! An edict from the sky-gods! Switch to it now!!

  21. Phil, love the blog!

    One thing that may be worth making a distinction about (and please correct me if I’m wrong). The supernova remanant is _actually_ 28,000 + 140 years old right?

    If I understand correctly, the light only started to *reach* us 140 years ago, but the star actually went nova much further back than that.

    This may seem like a quibble, but I’ve noticed that many of my friends can get caught up on this concept (“So… If it’s 28,000 light years away, but only 140 years old… how does this work?”)

    Keep on, keep on!


  22. AtomBasher

    doesn’t a star need to have a solar mass of at least eight solar masses to result in a supernova?

  23. Bill Rehm

    Maybe there’s a way to send an electric shock through the phone when somebody says stuff like that. It’s NASA after all… they should be able to do it. Maybe not though… As H.S. said, “How come you guys can go to the moon but they can’t make my shoes smell good?” I’m sure once they tackle the shoe scent issue they’ll get to improving call screening/caller punishment technology.

  24. Oops, the problem was already addressed by the time I got the post in. My bad!

    (And a double-comment post too – *shame*)


  25. BoC

    Very cool! To me, it looks like an eye (the “flames” being the lids) looking upward.

  26. Adela

    Well you could just say the explosion appeared in our skies 140 years ago for the nit picks.

  27. Fascinating news, thank you!

    With current observational technology, how long before we will be able to resolve more dynamics of the system?. Clearly it’s different over a period of 20+ years, but with better data, can we actually see the thing expand on a yearly basis, monthly, daily? can we actually watch the clouds move in anything akin to real time?

    Many thanks again, Jonathan

  28. Nuts. I had to leave the telecon to do some other stuff, and missed the fun. Oh well.

    And what I wrote above about relativity and time and distance is correct. It actually makes no physical sense to say this happened 28,000 years ago. That is a Newtonian way of thinking, not Einsteinian. Things get complicated when you’re talking about distant objects and time.

    If you want to stretch your brain, do a search on “relativity simultaneity” and see where that gets you. :-)

  29. SRM

    Ditto Adam, MarkH


  30. k.t.

    For what it’s worth, when I read the blog entry, I took it to mean it would have been observed (not actually blew up) during the civil war. Seemed a bit absurd to consider it really blew up during the civil war, the light blasted through space at many times (or…whatever) the speed of light, and now we see the remnant.

    Anyway, here’s a question (that might be too early to answer at all) but could that bright spot of the blue bubble be where the dwarf’s companion was/is (relatively speaking)?

  31. Todd

    It’s amazing to me that NASA couldn’t figure out how to secure their phone conference.

    They can put a person on the moon, shoot probes out of the solar system, and spot things like this that are incredibly hard to detect.. but can’t keep the 14 year olds talking about moon crickets and vaginas off their teleconference?

  32. AJ

    I’m just confused how we have a picture of it from 1985, and yet it being an “object in our Galaxy astronomers have been hunting for more than 50 years” and finally found?

  33. nvda

    So you’re saying it just assploded.

  34. Yoeman

    Todd is right, that was pretty ridiculous, 2 racial slurs over the air, although the panelists apparently had not heard those terms.
    The end of it was just sad, the Moderater hanging up, and the two
    guys not knowing if they we’re on the air or not!

  35. Alfredo Louro

    Is the confusion about the difference between “time interval” and “spacetime interval”? The latter would be ds^2 = dx^2 – c^2 dt^2, and “time interval” just dt? If that’s the case, I think ds is more meaningful because it’s an invariant. What’s confusing is to say that the explosion happened during the Civil War, meaning that explosion and the Civil War were simultaneous, which is not true in all reference frames. I think it would be clearer to say, the explosion would have been observed on Earth at the time of the Civil War.

  36. gigglesfor2012

    Where is the center of the explosion?…

  37. A few things to clear up here:

    1. Phil is correct about the “time” of the explosion. It seems odd, but it doesn’t make physical sense to talk about when something “actually” happened. This is why astronomers always talk about things in “Earth time,” this is, when we actually observed it.

    2. This is most likely the remnant of a Type Ia supernova, which does not result from a massive star, so it doesn’t have to be over 8 solar masses. Determining the type of supernova from the remnant is actually not a trivial thing to do, but we’re somewhat good at it, and can say with relative confidence that this was a Ia explosion.

    3. The bright spots along the periphery of the blast wave are not where the companion star is now. These are radio and X-ray images, where stars don’t show up, because they emit very little radiation at these wavelengths. Bright spots along the edge of a blast wave are generally caused by differing densities in the interstellar medium. Remember, this thing is several light-years across, and there’s no reason to expect that the ISM is uniform across those distances.

  38. Nossa a nasa demorou 50 anos pra descobrir isso.
    Seus viado da Nasa.
    E quem postou em inglês também.

  39. Nigel Depledge

    [nitpick mode]

    The BA said:
    “This sets off a chain reaction, and the entire star self-destructs. This creates an immense amount of energy — as much energy is released every second as the Sun emits for billions of years — and an octillion tons of gas is launched violently into space at a large fraction of the speed of light.”

    Huh? So, what happened to the first law of thermodynamics?

    Or, did you mean to say it releases an immense amount of energy…?

    [/nitpick mode]

  40. A pal recorded the teleconference and is available at

    About dates. Yes, the supernova is 28,000 light-years from here, but the light reached Earth 140 years ago. Hard to understand? Think of snail mail, before the Internet. A letter sent to you from a nearby city, needed only few days to reach you. Letters sent to you from a distant state, could take weeks or months. And letters sent to you from distant countries could take months or even years. The distance to the sender can be guessed looking at the timestamp. When astronomers say that this supernova happened 140 years ago, they really mean that its “letter” arrived on that date to the homebox (the Earth) and not when it was sent to us (28,000 years ago). On the average, they expect three letters per century in their homebox sent by supernovae on the Milky Way, no matter how far they are.

    Phil, one question. Don’t you think this is a NASA’s communication mistake? People were expecting a really big news all around the Internet and the actual one is far below the expectations. This could have an impact in NASA credibility.

  41. Todd

    Let’s keep in mind that the interest here is the observation of said supernovae, not when they *actually* happened (and in reality Phil’s reference to relativistic simultaneity definitely applies here). Since our observations are limited by the speed of light, as far as we’re concerned, this supernova we’re observing is in fact only 140 years old.

  42. gigglesfor2012

    Even though it is young in a cosmic sense the light from the center explosion is gone?… makes no sense

  43. I like this post a lot. Thanks, Phil.

  44. MarkH

    How about we agree on a semantical disagreement here, in that:

    1) the event itself happened ~28,140 years ago, and:

    2) the image we are seeing now is a snapshot of the event when it was ~140 years old.

  45. Todd

    “Even though it is young in a cosmic sense the light from the center explosion is gone?… makes no sense”

    At this stage in its life, it’s actually what we call a supernova remnant. Don’t forget these cease being an occurring supernova once all the gravitational potential energy is fully released from the confines of the now-collapsed star.

    What you’re seeing is the energy and hot gasses propagating outward from where the supernova was (and where the white dwarf or black hole now is).

  46. Todd

    Yeoman: I had no idea moon cr**ket was a racial slur and now I’m embarrassed to have repeated it. :(

  47. @gigglesfor2012
    That light is still travelling through the universe, but it is inaccessible to us.

  48. Gadren

    Phil, maybe I’m just not getting this, but I don’t see how you can call what we see right now as what is happening right now. You yourself have talked about galaxies 11 billion light-years away, and how they are much younger and are evidence of what galaxies may have been like in the early Universe. How can you reconcile this with the idea that everything we see is happening “now”?

    Unless there’s some reason that objects further from the Earth demonstrate properties of an earlier Universe, placing the Earth in the center, then what we see in the night sky has to be what was happening “there” at X years ago, where X is the distance in light-years.

  49. Will

    Just to back up Phil, in my astronomy classes every professor I’ve had has discussed objects in “Earth Time,” while we know how long the light took to reach us, it is mostly irrelevant as far as our studies go, and would make everything much more complex. For example it’s Supernova 1987A, not Supernova 177,013 B.C.-A.

    I didn’t find the post or language confusing at all, obviously it took a long time for that light to reach us, but since light, gravity, and everything in the universe is restricted to the speed of light, for most purposes it’s irrelevant whether it took 20,000 or 20,000,000 years for the light to reach us.

  50. Rien

    Phil, you mentioned type Ia supernovae (binaries leading to thermonuclear explosion), but I guess there is no way of knowing afterwards what type this was? Are core-collapses (Type Ib, Ic, II) less common?

  51. BMcP


    Yeah, I know what you mean by 140 years because to us this is what we see it as happening, I was just messin’ around, glad though you have a good sense of humor on that. :)

  52. csrster

    Sorry Phil, but I really think you’re wrong about this 28000-years-ago thing. Of course you’re right that simultaneity is relative, so to an observer zooming through our galaxy at close to c the time difference between us and the supernova will be very different from 28000 years. _However_ that’s just not relevant to the in point. The Earth and the supernova/remnant are moving slowly relative to each other and always have been. Therefore whatever _relevant_ reference frame you use (one attached to us, to the supernova, to the center of the galaxy) you’re always going to get the same result for the time difference between the supernova explosion and our local “now”, and it’s going to be the light-travel distance to the supernova + 140 years.

  53. Gadren

    @Will and BMcP:
    I definitely see the advantage of considering and labeling these events in relation to when Earth sees them, but what I’m wondering from Phil is whether we can truly call “Earth Time” reflective of reality. Considering that further objects show evidence of being from a younger universe, and that NASA’s own website has pages supporting this “seeing the past” idea (example:, I don’t see how anyone can say that distant supernovae are happening “now” in any sense other than a practical one for categorization/organization.

  54. beagledad

    Please, look at the first photo closely. Clearly it is the Eye of Sauron (though he looks a little sleepy). We’re all doomed, either in 140 years, or 28,000 years, or possibly right now.

  55. Heh. The title for this article as posted on reads, “Youngest galactic supernova (not aliens) found by Bad Astronomy.”

    Of course, it means “Youngest galactic supernova (not aliens) found” by Bad Astronomy (as a byline). It’s not as funny as “The Fly Gods Must Be Crazy Aliens,” but it’s up there.

  56. JulioCesar

    I was waiting to see that Nasa discovery. Now that I know it, I am happy. It is difficult to imagine few things more spectacular than a supernovae explosion (especially if it occurred in our own home galaxy).
    Such an event like this, well deserves beautiful headlines, coverage and follow up.
    However I will be waiting for more discoveries- headlines, i.e : dark matter finally unveiled, etc, etc.

    Thanks and greetings from Costa Rica.

  57. Evan

    It’s official name is G1.9+0.3

    I shall call him… George. And George is the coolest thing I have read about in a long time.

  58. Amy

    Rien: there are hints as to what type of supernovae a remnant came from in its chemical composition.

  59. PerryG

    Phil is right to say that there is no such thing as an absolute “now” in the Universe. This erroneous idea is called “absolute time” and it was a stubbornly held view of Isaac Newton. We can only measure events after light waves from that event can get to us (i.e., as we enter their light cones). Yes, the supernova happened 28,000 light-years away, so yes, from the supernova’s point-of-view it took 28,000 years for us to enter its light cone.

    For the sake of public understanding people like to say it the Newtonian way: that the supernova “happened 28,000 years ago”. To be technically accurate according to the ideas of Einstein’s Relativity, you’d have to say what Phil is trying to say and re-define our definition of “now” to mean all the events observable to us in our frame of reference.

    Think about what the universe looks like from Earth. Now think about what it would look like to someone who lived 2 billion light-years away. “Now” would look very different! If this being could “see” the Earth from 2 billion lt-yr away, they would see it as it was 2 billion years ago. This is the sense of “now” that Phil is referring to, and is really the only meaningful sense from the point-of-view of Relativity.

  60. csrster

    Perry, that’s quite correct, just as it’s quite correct that your reply was not “really” posted five minutes ago, but only five minutes ago in my and your local reference frames. From the point of view of a neutrino passing through the Earth, our replies are nearly simultaneous.

    However as far as the supernova-earth system is concerned, relativity is just irrelevant. The relative velocity of the earth and supernova is small and therefore, unless we adopt some arbitrary, weird reference frame, the time interval between the supernova exploding and that information reaching the Earth is 28000 years whether measured by an observer stationary with respect to the Earth or stationary with respect to the supernova. To say that the explosion occurred 140 years ago is ridiculous, since to get that time interval from the Lorentz transformation you would have to choose a reference frame traveling at some very specific value close to c.

  61. If you really want to nitpick, ask if it’s imperial tons or metric tons. And good luck on that one.

    There’s another way to determine the distance to these things. You have an expanding shell. First take a really good high resolution image. You assume that the shell expands at the same speed in all directions. You determine the doppler shift for material coming straght at you (and/or away) by measuring the spectrum – this gives you an expansion speed. Wait awhile. Take another image. This gives you an angular expansion speed, side to side. Do a bit of math, and you get the distance to the object.

    This has been done for the Crab nebula, and the results were in good agreement with historical record. So not only does the idea make some sense, it actually seems to work! Reason enough to celebrate.

    How many zeros in an octillion? Glad you asked. Just copy this question into your local Google search engine. Tell me if it isn’t – octillion: twenty-seven zeroes. That’s alot of zeros. Though not as many as in a gogle. Now, if you add up these zeros you get zero, right? But the whole universe comes from nothing… so it’s OK.

  62. The Truth

    It’s amazing the capacity of NASA!!
    The truth is:
    Since “Cold War”(USA/URSS), The NASA don’t receive a lot of money, and need to make a way to appear in media.

    These “news” are just a way to do this.

    The Chinese Spacial Agency is finding out things much more interest.

    Sorry for the english, i’m not north american! 😀

  63. Kol

    My primary-school-aged children understand that baseballs, vehicles, jets, sound, spacecraft and light all take different amounts of time to travel from point A to point B. While you guys quibble about relativity, pre-tweens already get the basic point. There’s also the medium through which the above examples travel if you want to really get meaty but honestly, you know? We get it.

    So, I was fortunate enough to come in late on this announcement. By that I mean that I didn’t have to sit through the theory and speculation of what “it” might be. I lost my taste for speculating about “It” when the result was a Segway. (shiver)

    This is really cool news to me! As an amateur genealogist, I can now point to specific members of my family and say that the light from G1.9+0.3 (bleeech. I’ll pick an ancestor and name it after them for reference) reached the Earth when those people were alive!

    There are all sorts of teaching tools springing up in my head regarding this one discovery.

    One lesson I learned while describing this news to my wife is that one must never use the term, “galactic hunt”, in an article. If you don’t annunciate each word while reading the article aloud, those four syllables can cause awkward laughter and red faces.

    No worries, BA. That article is elsewhere.

    My congratulations to all who spend their time correcting mental myopia. This one certainly made my vision sharper.

  64. Soren

    So NASA has this great moon conspiracy going,but they cannot keep the cranks out of teleconference.

    Clearly the crank was a plot to strengthen their lies about the moon hoax!

    (kidding,if anyone was in doubt)

  65. Out of curiosity, why was the photograph taken in 1985 not recognized as a supernova remenant?

  66. GodlessHeathen

    I’m confused. Is it “the youngest” or “the youngest known”?

  67. “G1.9+0.3” isn’t the best name ever, but it is a pretty neat piece of news. I’m very glad it wasn’t closer to us when it went nova…

  68. Tom

    It’s good that we all read these comments so we can learn and not continue to make the sa… argh … what’s happening …. must … post … something else ….. about the ………. 28,000 / 140 year .. things …. as though it …….. aaargh … hadn’t been ………… expained al….. ready…. *pant*

  69. Geekoid

    Thanks Phil.

    Phil is correct in saying 140 because whether you like it or not that is the common way to state these things.

    Hell, to an observer traveling with the light it just happened!

    I suspect that the announcement is just it’s age determination from a second photograph.

    I second naming it George~

  70. PerryG
  71. Keith Harwood

    I’m confused.

    I was under the impression that white dwarfs stealing mass from companion was the source of recurrent novae, not supernovas. I thought supernova was: massive star in last few seconds of life fuses innermost onion layer to form iron core, iron at bottom of binding energy curve so nowhere to go except collapse, form neutron star, neutrinos heat rest of star, splat!

    Or am I just showing my age again?

  72. Rien

    Keith, there are different types of supernovae. The ones that are called Type Ia are the ones that come from a binary system as Phil described above. Then there are Type Ib, Ic, and Type II. They come from a star that collapses as you described.

    I asked above if you could tell which type it was from the remnant and Amy answered that there would be a different chemical composition. I looked it up and type I don’t have any hydrogen lines in their spectra, which Type II have. Also, Type Ia can occur anywhere while core-collapses occur only in star-forming regions since that is the way very young and massive stars go.

  73. Rob P.

    While I’m willing to accept that that is the convention, I’m not quite so willing to say that it’s because that’s what relativity says. What Phil originally said is that the supernova “went off” at the same time as the Civil War. That’s only true from Earth. The only place where the two time cones intersect is here, and I’d say that you are the one who is asking for special treatment of a particular frame of reference, not me.

  74. Isaac

    13 light years across, and 28,000 light years away – roughly equivalent to looking at a CD-sized object 250-300km away.

  75. Is it quite certain that it would have been dimmed enough by the intervening dust and gas that it would have been invisible to the naked eye, at least? It occurred to me that, depending just where it is relative to the galactic center, it would have been effectively invisible if the light arrived here within a month or two of the winter solstice, when the Sun’s hanging around in those parts of the sky, making it eye-wateringly painful to point a telescope there, to say the least. So, the dust and gas doesn’t _have_ to be invoked to explain why it wasn’t seen. But, if it’s there, it’s there.

  76. Cooper

    So, on a website with nitpicks about movies and how they get the science wrong (like in Cloverfield where the sound reaches the viewers of the scene too quickly), we can overlook the fact that something occurred more than 28,000 years ago and say that it happened around the time of the Civil War and the thinking is that the general public is going to sort it out? I think this just adds to the general confusion people have about science by saying it actually happened 140 years ago. If you are going to nitpick about movies getting science wrong, don’t confuse the general public. I mean, if in Star Trek: Generations, the star goes out, the inhabitants of the planet wouldn’t know for several minutes but it happens almost instantly, do you really wonder why the moviemakers get it wrong?

  77. Chuck in NJ

    How come nobody knew it was a supernova 32 years ago in 1985 when the first photo was taken? AJon asked at 12:10 pm. John Meachamon asked at 3:10 pm. I’m #3.

  78. Chuck in NJ

    (I mean 23 years ago.)

  79. Ijon Tichy

    There’s nothing confusing or wrong about saying the following:

    “25,000 years ago, a supernova occurred near the centre of our galaxy; 140 years ago, the light from the supernova reached us here on Earth; 23 years ago we measured the light that was reaching us from the remnant of the supernova; and just recently we measured it again, giving us a more accurate estimate of just when the supernova occurred (as well as some interesting facts about the dynamics of supernova remnants).”

    It simply makes more sense when talking about objects and events in our galaxy to use the reference frame of our galaxy (i.e. the one where our galaxy is stationary in a translational sense). If that bothers you for some reason, then choose the reference frame of the CMB. And anyway, we don’t have to worry about special relativity because peculiar motions of planets, stars and galaxies tend to be tiny, insignificant fractions of the speed of light.

  80. Ijon Tichy

    On the other hand, I can see why astronomers refer to it as the youngest known supernova remnant, because we are observing the light from a 140-year-old remnant. All the information we get from it is from when it was 140 years old. Not as it is “now” in the reference frame of the Milky Way. So now I am of two minds about this issue, and I will shut up.

    But before I do: I used 25,000 light years as the distance in my original post because that’s what it says in this link:

    But in these papers:

    a distance of 8.5 kpc is used, which is closer to the 28,000 light year distance, so that’s what we should use.

  81. Jeremy

    you guys are so blind: its clearly the firefox logo

  82. Buzz Parsec

    The distance to the SNR is 28,000 lightyears, but how accurate is that estimate? It is very common in stellar astronomy for distance estimates to be plus or minus 25-50%, so it could easily be 20,000 ly or 35,000 ly. If an astronomer were to say “we expect the temperature of the remnant to drop below the ionization temperature of Oxygen in 28175 years” and then the distance estimate got revised, no one would know what actual date he was talking about. If he used the Earth arrival date of the change in light due to that effect of 2043, then everyone would understand and it wouldn’t be dependent on the distance.

  83. Lyle G

    The One Ring dissolving on the fires of mount Doom

  84. csrster

    Just to clarify, I think Rob P. is right that the convention of saying it happened 140 years ago is reasonable enough since, after all, what we are seeing is a 140 year old remnant (and also because in many cases we have no idea of the actual distance to astronomical objects). However, as Rob P. also points out, Phil is wrong in bringing relativity into his explanation – this is a non-relativistic system unless you start introducing arbitrary high-velocity reference frames. In which case we might as well forget about history as well as astronomy because, after all, Caesar crossed the Rubicon five minutes ago according to a neutrino I was just chatting with :-)

  85. Ijon Tichy

    Yes, indeed, there is a quite a bit of give and take in galactic distance determinations. You should read the argument given in the following paper for why a distance of 8.5 kpc was adopted:

    It’s a pretty good argument, admittedly, but it’s not something I would stake my life on. :)

  86. Grand Lunar

    The image resembles a brief shot from the “stargate” sequence of “2001”.

    I too am in confusion about the age of this event. Perhaps a blog entry explaining it might help.

    Anyway, this is pretty cool, and gives a revelation; how many more events similar to this, as well as other mysteries, are hidden in the viel of the galaxy’s dusty relm?

    I wonder if the James Webb telescope can find objects like this.

  87. csrstar and others: In our reference frame (and approximately that of the supernova) it is perfectly fine to say that the SN happened 28,140 years ago, but implicit in that statement is the assumption that the one-way speed of light is c. Reasonable though as it is, this is not an observable fact. The observable fact is that the two-way speed of light is c on average. To find the one-way speed of light, you need synchronized clocks at a distance. However, to synchronize clocks at a distance you need to know the one-way speed of light. You can never get around this, not even with slow clock transport (a la Eddington).

    The Google search term is “conventionality of simultaneity”.

  88. Sorry, I forgot to make my point: The point is that you can choose anything for the one-way speed of light, as long as the round-trip time is d/2c with d the distance. In particular, you can argue that it did not take the light any time at all to span the 28,000 LY (sic!).

  89. Blast! The round-trip time is 2d/c. Sorry for the multiple post.

  90. Beth Katz

    I liked Ijon Tichy’s description of the times: the explosion happened roughly 28,000 years ago, the initial light could have been observed on Earth 140 years ago, we did observe it 23 years ago, and now we have another photo and can use that to extrapolate the 140 as well as the 28,000.

    I had this discussion with my 13-year-old son last night after only skimming the article and seeing the brief blurb on the evening news. My kids seem to have no trouble with distance, time, and relative times. He’s hoping for Betelgeuse going supernova and posits that it’s already happened there (427 ly from Earth). But he wants to see it in his lifetime.

  91. bret mcdanel

    Bad Astronomer you said
    “Basically, the ultimate speed limit is light speed. That’s not arbitrary, it’s written into the fabric of spacetime. We cannot get any info from a distant object any faster than that.”

    That is incorrect, the speed of light is not a constant, it does vary. For example the speed of light in a vacuum is faster than when it goes through the atmosphere or a pane of glass. Yes it speeds right back up again the instant its past whatever object its going through, but the fact is that it does vary. So generally in space it will be at its highest, although it can arrive slower than the pure speed of light.

    Light also affects spacetime, it seems it does so more efficiently than gravity (a principle Dr. Mallet is using in his research for DARPA at U. Conn.). As a result spacetime may have some control over light and its speed, but light also has control over spacetime (gravity does too, such as the event horizon of a black hole). This is to say that space time is not the final arbiter of the speed of light since it can be manipulated, even by mere humans.

    This also disregards the theory regarding quasars (I dont know if this has been tossed or not, only heard it as unproven but would explain some stuff). Quasars are somewhat different from other objects, and one of the theories is that the speed of light slowed at some time in history. Of course if E=MC2 is to be upheld then you have a lot more matter instantly being created as the speed of light drops (a big bang of sorts). I do not know if anyone has used this concept to explain how the big bang came to be, I only heard it in the very limited context of quasars vs everything else.

    I wont go into quantum mechanics on how faster than light information systems can be fabricated, other than to say “quantum entanglement” for anyone who wishes to use google to read further. It would require an observation post far out in space and having a particle there and here entangled with each other, something we do not have so its kinda moot at this point (we also cant yet stop them from untangling themselves, usually after only a short interval but we can entangle in a lab currently and prove that it is possible).

  92. Paineroo

    > But observationally, it’s been more less than more.

    I would have preferred it if you had phrased this as “it’s been more less and less more.”

  93. bret mcdanel

    I forgot one other reason why light isnt the absolute speed, although this is minimal. If light is traveling towards us at um well the speed of light, and we are traveling towards it at um well any speed, it will actually arrive faster (based on frame of reference).

    Now if we were to take this further, for illustrative purposes, you are traveling in a space ship at half the speed of light. I am traveling in the opposite direction at half the speed of light. From my frame of reference, you are at the speed of light, something that in theory you shouldnt be able to do. From your reference I am traveling at the speed of light, something I shouldnt be able to do. From a 3rd party watching these shenanigans we are each going half the speed of light.

    If we exceed half speed, then from our frame of reference, the other is traveling faster than the speed of light.

    Well the earth is moving, however slow compared to light, so roughly half the year light will take slightly longer to catch us, while the other roughly half year it will take less time.

  94. The speed if light in empty space is constant. (And yes I know there is no such thing as empty space.) Saying it happened 140 years ago is the only sane way of phrasing it. 😉 It someone starts acting all confused, add “140 years plus 28.000 lightyears”; that ought to do the trick.

    And when I go to a movie and the sun goes out, I don’t want to wait 8 minutes to see the effects. I want to see havoc RIGHT AWAY, lest my popcorn gets cold first.

  95. @bret

    “you are traveling in a space ship at half the speed of light. I am traveling in the opposite direction at half the speed of light. From my frame of reference, you are at the speed of light”

    You can’t just add 50 % to 50 % and get 100 %, that’s not how relativity works.

  96. The method to determine distance where you take spectrum, and two images spaced in time is cool. But if a light echo could be found, that would be even cooler. We know how fast light goes. You check the angular size of the echo, and a little math gives you the answer. Instant gratification. Unfortunately, we’d need a light echo that we can actually see in some wavelength that makes it here.

    Some great work of this kind was performed for the large megellanic cloud. An image was taken, a few years of wait, then another image was taken. When you subtract one from the other, the light echo can emerge. Of course, we’re back to waiting…

  97. Mars

    Something to note, anyone whos played Mother / Earthbound Zero, check out the final battle against Giygas / Giegue. Notice anything?

  98. Gavin

    So now that everyone is thoroughly confused and irritated over time reference questions ( 😉 ), do we still not have an answer to the 1985 question? I scanned the thread but could only find the question asked again and again, to be brushed aside for the other argument.

    I assume they went back to some archival pics that happened to have the supernova there that no one noticed, but it’s odd given how similar the photos look. Did they know what this was in 1985 or not?

  99. Tina

    I’m glad people have made comments about the age of the supernova NOT being 140 years. Simple errors like that that mislead the general population iritates me like nothing else. Props to those who question this article!

  100. Beth Katz

    Gavin, if you go read the Chandra article (link at top), when this was seen in 1985 with the VLA, they thought it would have been first observed 400 to 1000 years ago. (This funky way of describing dates is why we just say it is 400 to 1000 years old even though that’s when it could first be detected on Earth as if we had radio telescopes in Shakespeare’s time. It’s just awkward.)

    Anyway, being scientists, they went back and looked at it again to see if anything had changed. They saw it had expanded more than you would expect for something that old. So they recalculated the age making it the youngest we’ve observed even though it may not be the one that happened most recently.

    So now, I’d guess that they are continuing to use Chandra to check other supernova remnants they’ve previously observed with VLA and seeing if there are similar changes. That’s the power of using different instruments to examine the same object as well as a spread of time.

  101. Torbjörn Larsson, OM

    Great! I didn’t know that there was such a worrying discrepancy in recent super nova rates, but I do see that observing these young ones will improve the statistics.

    And I assume that the asymmetry, unexpected speed of the remnants and just the ability to observe the gas and dust dynamics will be important to models of super novas, seems to a layman they still change them nearly every time a neutron star have some unexpected characteristic.

    How come nobody knew it was a supernova 32 years ago in 1985 when the first photo was taken?

    According to the press release they did – they didn’t know it was so young before the expansion rate of the gas was pinned down. “Based on its small size, it was thought to have resulted from a supernova that exploded about 400 to 1000 years ago.”

  102. fred edison

    It’s a fantastic find and about time after waiting so long. I listened to what R.C.H. had to say on the 5-14 C2CAM show about this NASA announcement and its state of affairs in general. Always a guaranteed hoot. Keep up the good…errr….bad astronomy. Hope to hear you back on the airwaves sometime.

  103. Torbjörn Larsson, OM

    I really need to post a FAQ on this!

    Well, you should, as this little convenient convention isn’t well known AFAIU. IIRC many popular texts use the light travel time reference.

    “conventionality of simultaneity”.

    Seems to be a philosophical discussion. Our local Minkowski spacetime seems to be based on the parsimonious physical theory of Einstein.

    @ bret:

    That is incorrect, the speed of light is not a constant, it does vary.

    By convention it is the vacuum speed of light discussed if nothing else is mentioned. (And since that is the only one which is constant, it is logical to assume Phil is discussing it.)

    Light also affects spacetime, it seems it does so more efficiently than gravity

    Back reaction from EM energy doesn’t change (vacuum) light speed.

    I wont go into quantum mechanics on how faster than light information systems can be fabricated, other than to say “quantum entanglement” for anyone who wishes to use google to read further.

    Quantum entanglement doesn’t provide faster than light informational speeds.

  104. someguy

    It does remind me of aliens still.

  105. StevoR

    Drat! I almost had it with my guess about perhaps finding the missing pulsar for supernova 1987 A …

    Supernovae ..Tick
    Remmnants .. Tick
    Actual discovery .. Bzzzt! Wrong ‘un.

    It is, as stated, the youngest supernova remnant found in our Galaxy – forma star too dust shrouded for us tosee it go BOOM! when it went back around the US Civil War Time – or in non-US speak … 1868 was

    – During the Victorian Era – the reign of Queen Victoria for the Brits!

    – The year after the abolition of the Tokugawa Shogunate for the Nihonjin (Japanese) out there ..

    – During the Manchu (Manchurian) or Chi’ing Dynasty -the last Imperial dynasty to rule China for the Chinese folks reading this…

    … To list but three other examples.

    That is an awesome finding!

    Although not perhaps quite up to the pre-announcement hype …

    If anything I can’t help think gee what a shame we all missed seeing it … & wondering when the next supernova in our Glaxy may happen. Hopefully soon! I’d love to see Eta Carinae & / or Betelgeux detonate in my lifetime! 8)

    Mind you, having Sirius B or Procyon B suddenly (& highly unlikely-ly!) blow up on us would not be so welcome! ;-O

  106. StevoR

    Mohamed on 14 May 2008 at 11:08 am


    What the … ???! What a very weird opening comment here.

    Er, Mohamed , I don’t get it. What’s so bad about this discovery then? :-(

    Or if Mohamed is a joke ID tag indicating this is somehow ahorrible discovery for Muslims well I’m still as puzzled. How does this supernova
    remnant hurt the ‘Dar-al-Umma’ (Islmaic world)

    Is it because the Arab astronomers missed it?
    But then so did everybody else & it wasn’t their fault but the dusts..

    Because it has some special Muslim significance? If so that sure escapes me …

    What are you on about there …???

  107. Perhaps he was betting on the aliens.

  108. While I agree that this probably very exciting for a select few people, most people are going to wonder why all the suspense for something that happened 28,140 years ago. also if they have images from 1985, why say it’s been something that NASA has been looking for “for the past 50 years”? the 1985 pics suggest that they only had to look for 27 years. This is almost as disappointing as an Uwe Boll movie.

  109. hassen

    Hey guys, in the first paragraph it says that something the size of the sun could create a catastrophic event. But our sun or any satrs like it are to samll to explode.

  110. hassen

    I am a 15 year old kid from calgary alberta asking a science question, could the sun blow up because my teacher believes that the sun is way to small to implode or explode.

  111. Bob

    AHHH! Giegue!

  112. Jonathan


    Take a melody
    Simple as can be
    Give it some words
    And sweet harmony

    Raise your voices
    All day long now
    Love grows strong now
    Sing a melody of love, oh love

  113. Ninten

    Guys don’t worry. We already took care of Giegue years ago. That’s just the remnants of it’s capsule, floating around space.

  114. B Fenerty

    When presenting informal talks at our Science Centre, to the public who are visiting free weekly telescope observing, for dating something like a supernova I use a word such as “appeared” rather than “happened”. From there it is easy to build on the distinction between the two wordings, and reveal to or remind the audience how telescopes show things that happened often very very long ago, that many distant things we see through telescopes may no longer even be there anymore in terms of general public thinking. Using “happened” instead of “appeared” may be okay among experienced sky watchers who understand the shorthand language, take relativity issues as obvious, et cetera – but for the general public it wastes the above described opportunity to teach good astronomy. This is especially important for young members in the audience, since some may be inspired to become scientists if they see key concepts being used carefully and thus capable of exciting implications. B Fenerty (member Royal Astronomical Society of Canada)

  115. Isaac Lands

    Okay, since im just a 6th grader, i might not know as much as you guys do about this subject. But since its a supernova shouldnt it explode? I mean its cool and all to have one in the galaxy not exploding but its still kind of scary because if it gets really big and then explodes wouldnt some of the explosion reach our planet? Some of my friends and I are researching stuff like this on the internet but were mostly finding a load of garbage. Stuff like people going “space crickets are real and are going to come eat us all!!” its getting really stupid finding that all the time, so if someone can please enlighten me on some more info about this.

  116. Holy cow, it’s Giegue from Earthbound Zero! Everybody sing for your lives!

  117. steve

    oh my gawd! it looks like giegue from mother 1/earthbound zero!!! if ur not a fan, look him up

  118. Soiherduliekeb

    I-It’s GIGUE!!!


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