No danger at all.
Well, the thing would be about as bright as the moon, so I guess maybe somebody could crash their car staring at it. Also, maybe increased incidence of werewolves?
I wouldn’t say no environmental effects at all. There are probably some living things for whom moonlight levels are relevant, and the addition of another light source comparable to the full moon might be disruptive to them.
But that’s about it.
Light is radiation. Whatever gamma rays and X-rays we get from the supernova (and there will be some, just not enough to worry about) will arrive here exactly as quickly as any other sort of light.
Corals use the full moon to synchronize their spawning. But they also use other environmental factors, such as water temperature, too. And they only do it once a year. If the supernova happens at the wrong time, it might change the timing. It’s possible that that might delay it too much and the spawning won’t be very successful.
Likely he meant high energy particles from it. Neutrinos will get here before the light does. We don’t know the exact speed of neutrinos, but it’s really, really close to that of light. But it also will escape from the supernova immediately, while the light will take a few hours to work its way out. In fact, there’s a Supernova Early Warning System, a collaboration of various neutrino observatories, that will alert astronomers to supernovae based on the detection of large numbers of neutrinos.
Other stuff will get here at various times depending on how much energy they have. There’s no specific speed of electrons, protons or other particles in space.
Which in turn means that those other particles would be even less dangerous. Even if the supernova produces a sharp pulse of, say, protons, they’ll be at a wide range of different energies, and hence speeds, and hence arrive here over a very long period of time instead of being a sharp, sudden pulse. Like, if one proton is going 99% of the speed of light (a quite impressive speed for a proton), and another is going at 98% of the speed of light, there will be over six years between their arrivals.
Another thing is that for charged particles (electrons, protons, alpha particles, etc.), the less enegy they have, the more their path is modified by the galactic magnetic field. So those will take a longer path to travel here, which of course, takes more time.
Most countries have gamma, neutron and alpha detectors placed at ports to screen incoming traffic and passengers for radioactivity.
Am I right in thinking that those detectors will malfunction if said giant goes supernova?
Neutrons won’t make it here at all. They have a half-life of around 15 minutes, far too short, even at ludicrous time dilation factors, to make it 640 ly.
Alpha particles could make it here, but really, really slowly (by radiation standards), and they’re stopped by almost anything.
Gamma rays will make it here fine, and will be detected by satellites, but the atmosphere is actually mostly opaque to gamma rays. Again, surface instruments won’t see much.
Ground-based neutrino detectors will definitely detect it, but nobody but scientists has any reason to care about neutrinos.
Moths would get lost, or at least very confused. Likewise any other critters that navigate by moonlight.
Every person on Earth would get about two dozen neutrino interactions in their body from a Betelgeusian supernova. Not biologically relevant, but neat.
If I get some kind of chance neutrino interaction, might it turn me into some sort of mutant super-hero?
Will these neutrinos be particularly energetic? I thought each of us would be struck by only a few quadrillion extra neutrinos when Orion’s Right Hand explodes; is that enough to make interaction likely? IIUC, each of us is attacked by far more neutrinos than that over a lifetime, but is lucky (unlucky?) if even one interacts with us.
Statistically, I think it’s more likely to turn you into some sort of mutant super-villain.
[I haven’t done rigorous statistics, but every mutant super-hero seems to have fought multiple mutant super-villains]
What are the critters that navigate by moonlight? The only one listed in wikipedia is the scarabaeus zambesianus, an African dung beetle.
My estimates:
Of the kajillions of neutrinos passing through you normally (mostly from the sun), one will interact with an atom in your body on average every five years for a lifetime total in the teens. Betelgeuse going supernova would surpass this total, producing 20 or so interactions in your body in just a few seconds. And Betelgeuse is 4x10[sup]7[/sup] times further away from us than the sun. Core-collapse supernovae are… impressive.
Regarding energies: The neutrinos themselves are about as energetic as (or just a bit more energetic than) typical products of nuclear radioactive processes, with energies mostly in the 5 MeV to 40 MeV range.
For what it’s worth, one of my old professors studies Betelgeuse. I asked him what he thought of the recent dimming, and he says that it’s certainly at an unprecedented low, but that he doesn’t think that it means the end is imminent (though he reiterated that nobody knows what it looks like that a star is about to blow). He thinks the dimming is most likely due to a drop in temperature due to pulsations in radius, but that some folks are entertaining the notion that it’s exhaled a dust cloud that’s partly obscuring it.
I’m surprised that spectroscopic observations haven’t ruled out one of the theories by now.
I’m guessing that the difficulty there is that Betelgeuse isn’t one uniform temperature, so its spectrum will be more complicated than tat of a smaller star. I’m sure it’s being studied, but the analysis takes time. Especially since the grad students are probably on break.
Grad students take breaks now??
I thought dust was fairly conspicuous in IR, but I suppose if it’s a newly produced dust cloud, it wouldn’t be in thermal equilibrium and be difficult to understand the observations.
never underestimate the power of astrologers.
:eek: