Gamma-ray bursts.

We really need some kind of overarching committee to keep track of these kinds of things, and prioritize them, and postulate potential solutions to them in keeping with those priorities. I think I feel an article coming on...

Rand,

Well, there is always this book, for starters:

"Risk: A Practical Guide for Deciding What's Really Safe and What's Really Dangerous in the World Around You" by Ropeik & Gray.

I haven't read it myself but recall it getting pretty good reviews when it came out.

Given the miniscule interest in detecting and or preventing the rather more likely chance of an asteroid or cometary impact, I doubt anyone in any position of authority is going to do anything.

And if a gamma ray burster is really close, the earth gets a really big dose of ultrarelativistic protons from the fireball. These arrive over a period of months, and the secondary muons sterilize anything not under more than a kilometer of rock.

If that happened, humanity might survive if we've burrowed into some big asteroids. Otherwise, fini.

Being sterilized by gamma rays would make me so mad I'd turn green, grow to be nine feet tall and 600 pounds, and smash everything in sight.

It's amazing how many "scientists" of various types seem to find doomsday scenareos which, in order to assure human survival, requires lots and lots of money for research in their field. Of course, the probability of these scenareos happening sometime in the next 1000 years are infinitesimal, but hey, when the outcome is total extinction the expectation value becomes large enough to stimulate an info-tainment drone to leave the electronic equivalent of a steaming pile on the information highway.

We'd have to build a genetic cloning automation facility deep underground with mapped genome sequences of all known species of animals and of course humans. Once every 100 years or so we'd just have to send a ULF signal to the automation system to let it know we are still here and kicking. Once a catastrophe struck though and the system received no signal it would activate and begin replication processing. These organisms would then be delivered back to the surface to reseed the Earth's post apocalyptic biosystem and try to restart life as we knew it.

Eta Carinae (at around 7500 light years distance) is the only candidate that I'm aware of that might generate a gamma ray burst in the (relatively) near term. At that, the beam has to be pointed at Earth to be an issue. These stars have to be massive, which means they evolve very quickly, so they are quite rare. They are also quite bright, so it is easy to find them. I'm not terribly concerned about this particular issue.

VR: there's probably more than one source of gamma ray bursts. Massive stars are probably the source of 'long' bursts, but there's also (in the observations) a class of very short bursts, which may be due to coalescing neutron star pairs or neutron star/black hole pairs.

I would have imagined The Guardian listing the reincarnation of Margaret Thatcher in this particular list.

A fair amount of really bad stuff has happened in the past. If it happened once, it could happen again: ice ages -- otherwise known as climate change, getting whomped by asteroids and comets; gamma ray bursts, pandemics, vulvanism, and other assorted delights.

Those are not our fault, but assuredly The Guardian will labor to make us feel guilty.

Certainly there are things we puny humans could do to wipe us all out -- nuclear war followed by nuclear winter comes to mind. But that's only true so long as Earth remains the only host for our species.

Personally, I subscribe to the "Aliens Aren't What They Seem" scenario.