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Given that the stars' distances to Earth are measured in light-years (for example, Sirius is 8.6 light-years away from Earth), what we are seeing as Sirius now is actually its state 8.6 years ago, right?

So it is possible that a star (maybe not Sirius, I don't know, it's just an example) somehow explodes and creates a supernova, and if this is the case, we will see this event 8.6 years later (I assume everything is right up to this point).

So my question is, is it possible for me while looking at the sky on a lucky day, suddenly see the explosion of a star that happened x years ago and be the first eye witness of this event? In other words, is there a technology on Earth (emphasis on "on Earth" here, the satellites or space shuttles do not count since they might be slightly closer to the star than the Earth is) that can see this before me?

My logic is that even the greatest telescope "sees" whatever light it receives. So since a telescope cannot increase the speed of light it receives, it shouldn't be more fast than me. And since light is the fastest way of transferring information, I assume that I am as possible as NASA to see such an event. Is there any way this assumption is wrong?

HDE 226868
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jeff
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2 Answers2

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Naked eye nova are fairly common, several per year. Here's one. Naked eye supernova are far rarer. SN1987a in the large Magellanic cloud was naked eye visible (vid). From this list, it appears the supernova in 1987 was the most recent naked eye supernova. There was a naked eye gamma ray burst in 2008, but I don't think anyone actually got outside in time to see it.

If you have 50 years to look at the stars, you might see a supernova. If you have a small telescope, you can pick them up pretty regularly in nearby galaxies.

Wayfaring Stranger
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  • Thanks! I do have a telescope but it hardly lets me to see the satellites of Jupiter. Do you think I can be able to see one? And how frequent do you mean by "regularly"? – jeff Aug 27 '15 at 12:09
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    They're usually one or two a year in one or another of the Messier object galaxies. You have to keep up with Sky and Telescope http://www.skyandtelescope.com/ or similar, to find out when and where. – Wayfaring Stranger Aug 27 '15 at 12:13
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Supernova create huge spikes in neutrino emissions. Since neutrinos pass through a stellar mass mostly unimpeded, they're visible up to 3 hours before the shockwave even starts to affect the star's surface.

Since neutrinos travel at the speed of light, they will always keep their 3 hour head start. Thus, unless you have a neutrino detector buried a few miles below your house, you're unlikely to be the first to observe a naked eye supernova, even with a telescope pointed directly at the star.

The first supernova definitively detected by a neutrino spike before it was visible was SN 1987A.

As more neutrino detectors come online, and as their ability to pinpoint the exact direction that neutrinos come from is improved, it's almost certain that the next naked eye supernova will have dozens of observatories and thousands of amature telescopes pointed at it before it's even possible for these telescopes to detect the event.

Jerard Puckett
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Ghedipunk
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    Slight clarification: We don't know if neutrinos can travel at the speed of light. – HDE 226868 Aug 27 '15 at 18:54
  • Just curious, where are you getting the three hour figure from? Does it take that long for a Supernova to propagate from the center of the star to the star's surface? – Sidney Aug 27 '15 at 18:58
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    @HDE226868 -- It is close enough to the speed of light that, over 180,000 lightyears, the neutrinos arrived between 2 and 3 hours before the photons for SN 1987A. – Ghedipunk Aug 27 '15 at 19:10
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    @Sidney -- The 3 hours comes from the Wikipedia article on SN 1987A, which says: "Approximately two to three hours before the visible light from SN 1987A reached Earth, a burst of neutrinos was observed at three separate neutrino observatories." ---- Other sources say it could be up to tens of hours, such as Dr. Ian O'neill of Discovery News: http://astroengine.com/2008/03/10/how-do-you-catch-a-supernova-in-the-act-build-a-neutrino-detecting-early-warning-device/ -- though that's not based on a scientific paper, so put your skeptic hat on. – Ghedipunk Aug 27 '15 at 19:13
  • @Ghedipunk I know, that's why I called it "slight". – HDE 226868 Aug 27 '15 at 19:16
  • @Sidney, it would be very interesting to see a SuperNova up close. You wouldn't see the inner core collapse, but as it happens, Neutrinos formed would start to fly outwards. Neutrinos are mostly irrelevant to the outside of the star and most pass straight thru but enough of them creates an outward pressure on the outer layers of the star. I gather it takes about 1 second for the inner core to collapse, but it takes a couple/few hours for the outer core to actually fall in and rebound in what we think of as the Nova explosion. It would be an awesome thing to see (from a safe distance). – userLTK Aug 27 '15 at 23:42
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    If you're watching a supernova from up close, make sure you don't get radiation poisoning from the neutrinos. – Mark Aug 28 '15 at 00:17
  • Neutrinos have mass. Therefore we know that they do not travel at the speed of light. The interval between neutrino pulse and observed supernova is in fact diagnostic of that mass. – ProfRob Aug 28 '15 at 05:23
  • @Mark : Also, be sure to wear dark glasses or a welder's filter. As with staring at the Sun, supernova light could easily cause blindness. – Wayfaring Stranger Aug 31 '15 at 15:01