I know star phenomena like solar flares can (at some degree) be predicted:

Question: Is there any phenomena in a star that could be used to predict its supernova explosion with years or decades of advance notice?

Answers to Are there observable changes in a star about to become supernova, minutes or hours before the explosion? address shorter timescales like hours or days, but I'm looking for times that are orders of magnitude longer than those discussed there.

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    $\begingroup$ Some massive stars experience a great eruption before its final collapse, and explosion. This has been observed in some cases like the most well-known SN 2009ip. So, yes to the question. However, it is hard to predict if a star will ever has the eruption, or how long before the final collapse. $\endgroup$ Dec 27, 2018 at 23:06
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    $\begingroup$ Out of curiosity, how far in advance would you want the supernova to be predicted - and to what precision, in time? $\endgroup$
    – HDE 226868
    Dec 27, 2018 at 23:12
  • $\begingroup$ Betelgeuse: The Eventual Supernova space.com/22009-betelgeuse.html Some speculate that it has already blownn and we are just waiting on the light. $\endgroup$ Dec 28, 2018 at 16:47
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    $\begingroup$ @HDE226868 I know the prediction could be interpreted based on the neutrino emission of the star (a good answer here: astronomy.stackexchange.com/questions/18423/… ) But I am looking for some other way of predict it with more than a few days in advance (years or decades). $\endgroup$ Dec 28, 2018 at 18:00
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    $\begingroup$ Are you specifically interested about massive stars exploding, or do you also want to consider type Ia supernovae? $\endgroup$
    – user24157
    Dec 29, 2018 at 12:21

3 Answers 3


While a whole slew of signals will arrive once the supernova actually occurs, from neutrinos to light of all different energies and wavelengths, the outward, visual appearance of the star will not give any surefire clues that a supernova is imminent. But the nuclear reactions powering the star do change over time, and at just 640 light-years away, Betelgeuse’s neutrinos may give us the early warning signal we need to predict its supernova accurately, after all.

If we want to know what’s going on in the core of a star — our only true indicator of when a supernova is coming — observing the electromagnetic properties of the star won’t give it to us; there is no change in a star’s temperature, brightness, or spectrum that occurs after the transition from carbon-burning to heavier elements.

But the neutrinos tell a vastly different story.

In the lead-up to a supernova, the neutrinos carry away the vast majority of the energy produced in those core fusion reactions. For the carbon burning phase, the neutrinos are emitted with a particular energy signature: a specific luminosity and a specific maximum energy-per-neutrino. As we transition from carbon-burning to neon-burning, oxygen-burning, silicon-burning, and eventually the core-collapse phase, both the energy flux of neutrinos and the energy-per-neutrino increase.

During the silicon-burning phase, neutrinos are produced with higher energies than previously, and as the silicon-burning phase continues, shells of silicon fusion begin forming around the core. In the final few hours of this star’s life, shortly before the core collapses, the neutrinos produced cross a critical energy threshold. Your antineutrinos can then interact with the protons in your detector, producing a unique signature: neutrons and positrons, an unmistakable signal of inverse beta decay.

Under normal circumstances, inverse beta decay events are extreme rarities in neutrino detectors, coming about only when a random neutrino from the Universe strikes our sophisticated neutrino detectors. But if a star were burning silicon in its core and had crossed that critical energy threshold to produce sufficiently energetic antineutrinos, and if it were close enough, we should see a large number of inverse beta decay events that all come from the same direction.

  1. "..phenomena like solar flares can be predicted" It depends on weather. Solar weather. And timescale. BUT you cannot predict it's motion. Solar dot measure, any of this form - is unpredictable. It may go down, it may go up - both ways 50/50. Stochastical process. The process itself is non-linear. You can have solar weather in some bounded range, but you cannot say what it will be tomorrow. "Soft physics" works on such things. Still some unexplained things, same as in meteorology.

  2. "could be used to predict its supernova explosion" Yes. Direct observation of star could be useful. From close range. With magnetometric, X-ray etc. Which none of us have. On the other hand, supernova relies on changes in chemical constituents in star material. It could be defined.

  3. "but I'm looking for times that are orders of magnitude longer than those discussed there". Yes, there is. Chain of events starts with changes in spectrum, which corresponds to changes of chemical structure in star material. Knowing all star parameters (from close range), you can have the time until event. Ofc you cannot definitely say what follows, because small changes in parameters are varying outcome --- either there will be white dwarf or neutron star etc.

Ofc you cannot compute exact second of event, because (first) there is no such thing. Event occurs continiously. And, second, your prediction will rely on existing star models, and equipment accuracy. So if you measure with accuracy of 2%, do not expect prediction be more precise then 2%. Common practice shows that model makes more miscalculations almost always (99% of events miscalculated are from wrong models and/or miscalculated model range).

Consider weather prediction. It fails. When it fails, nobody notices. Because it fails when model fails. It fails less often then it works, but it happens. It doesn't fail catastrophically, that's why nobody notices. "Oh, it's more colder at 4 o'clock, but prediction said it will get colder at 2 o'clock" - nobody says that. It happened anyway, but model was slightly out of range.

PS. Also categorize exactly what prediction means. Because there is still no such thing as "prediction". In science, we say that "time period until Moon falls on Earth is 200-300 billion years". Always in range. According to model. And according to data.


Instead of asking the question "when will it explode?", you can instead ask "when will it appear in our sky?". The latter question can actually be predicted reasonably accurate in rare cases.

One such case was in 2015, with the appearance of supernova Refsdal. Its appearance was predicted a couple of months in advance.

They could make the prediction because of gravitational lensing. If the light of a supernova has more than one possible path around an intermediate heavy galaxy or galaxy cluster, acting as a gravitational lens, then some paths may be longer that others. That is, the supernova can appear on one side of the gravitational lens earlier than on the other side.

In the case of Refsdal, four images of the supernova were discovered in 2014, and through heavy calculation they could predict that it would appear in a fifth place in December 2015. See Hubble news for more details.


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