8th Century Gamma Ray Burst Irradiated the Earth, Study Finds

[N2NH]

It was recently found that the Earth was likely irradiated with gamma rays from a source in space in 774/775 AD.

In 2012 scientist Fusa Miyake announced the detection of high levels of the isotope Carbon-14 and Beryllium-10 in tree rings formed in 775 CE, suggesting that a burst of radiation struck the Earth in the year 774 or 775. Carbon-14 and Beryllium-10 form when radiation from space collides with nitrogen atoms, which then decay to these heavier forms of carbon and beryllium. The earlier research ruled out the nearby explosion of a massive star (a supernova) as nothing was recorded in observations at the time and no remnant has been found...

Drs. Hambaryan and Neuhӓuser have another explanation, consistent with both the carbon-14 measurements and the absence of any recorded events in the sky. They suggest that two compact stellar remnants, i.e. black holes, neutron stars or white dwarfs, collided and merged together. When this happens, some energy is released in the form of gamma rays, the most energetic part of the electromagnetic spectrum that includes visible light. In these mergers, the burst of gamma rays is intense but short, typically lasting less than two seconds. These events are seen in other galaxies many times each year but, in contrast to long duration bursts, without any corresponding visible light. If this is the explanation for the 774 / 775 radiation burst, then the merging stars could not be closer than about 3000 light years, or it would have led to the extinction of some terrestrial life. Based on the carbon-14 measurements, Hambaryan and Neuhӓuser believe the gamma ray burst originated in a system between 3000 and 12000 light years from the Sun.

For those who have said that these events do not happen, here is proof that it not only does, but it has. If it were closer, it would've "led to the extinction of some terrestrial life." Yes, all that life that was on surface of the Earth facing the event.

8th century gamma ray burst irradiated the Earth, study finds

[VE7DCW]

It's my understanding that the gamma rays were emitted from a tertiary subspace anomoly located in spatial grid 1593!

[N8YX]

Option 3:

A nearby magnetar underwent a starquake and the resulting uncoiling of its magnetic field triggered a gamma ray burst. A similar event happened just a few years ago and was the first such event detected by spaceborne instruments.

[n2ize]

I dont; recall anyone saying these events don't happen. Actually they do happen and have been known to be for quite some time. Fortunately they happen to be quite rare within any given galaxy, and generally occur in distant galaxies and are harmless to the earth. However, if a nearby burst were to occur, say within our galaxy (although the probability appears to be extremely small), then all bets are off and the results could be catastrophic.

[N2CHX]

I dont; recall anyone saying these events don't happen.

Really? Obviously you haven't talked to any religious educators lately.

[KC2UGV]

I dont; recall anyone saying these events don't happen. Actually they do happen and have been known to be for quite some time. Fortunately they happen to be quite rare within any given galaxy, and generally occur in distant galaxies and are harmless to the earth. However, if a nearby burst were to occur, say within our galaxy (although the probability appears to be extremely small), then all bets are off and the results could be catastrophic.

We had one happen, in our galaxy. We had a nearby starquake that did this: SGR 1806-20. It was on the other side of the galaxy, and increased the size of our magnetosphere quite a bit. If it were within 3 parsecs, it would have been a life-ending event here.

[N2NH]

We had one happen, in our galaxy. We had a nearby starquake that did this: SGR 1806-20. It was on the other side of the galaxy, and increased the size of our magnetosphere quite a bit. If it were within 3 parsecs, it would have been a life-ending event here.

Current estimates are that a gamma-ray burst will happen in our galaxy, or one nearby, about once every five million years. However, there is a good chance that the radiation would not have an impact on Earth. This is because it all depends on the beaming. Even objects very close to a gamma-ray burst can be unaffected, just so long as they are not in the beam path. However, if an object is in the beam path, the results can be devastating.
There is evidence that suggests that a GRB could have occurred about 450 million years ago, which could have led to a mass extinction. But this is uncertain.
But what if a gamma-ray burst, beamed directly at Earth, happened today? Well, first of all, in that unlikely event, the damage would still depend on how close the burst is. For argument sake, lets assume that it occurred in the Milky Way galaxy, but very far away from our Solar System.
With the gamma-rays beamed directly at us, the radiation would deplete a significant portion of our atmosphere, specifically the ozone layer. Additionally, the photons would cause chemical reactions leading to photochemical smog. This would further deplete our protection from cosmic rays.
And then there is the lethal doses of radiation that surface life would be exposed too. The end result would be mass extinctions.
Luckily, the statistical probability of such an event is low. We seem to be in a galaxy where supermassive stars are rare, and binary compact object systems aren't dangerously close. And even if a GRB event happened in our galaxy, the likelihood that the event would be highly beamed directly at us, with nothing between us and it is even more unlikely.

In our Galaxy... once in about 5 million years.

One 3,000 to 12,000 LY away in 775.

So I guess we're safe for another 5 million years?

Don't you believe it.

[KC2UGV]

In our Galaxy... once in about 5 million years.

One 3,000 to 12,000 LY away in 775.

So I guess we're safe for another 5 million years?

Don't you believe it.

It's estimated it happens once every 10 years or so. Safe? Meh. What are we supposed to do about it anyways? I'm not sure, but I don't think we have the technology to stop magnetars from doing what they do.

[n2ize]

It's estimated it happens once every 10 years or so. Safe? Meh. What are we supposed to do about it anyways? I'm not sure, but I don't think we have the technology to stop magnetars from doing what they do.

In our galaxy (or others of similar size) the expectation of a GRB lies between once every 500,000 to 1,000,000 years. If one were to occur in our galaxy the degree of impact on earth would depend on many factors, i.e location, distance, collimation, and direction. If it's aimed right at us we could be in for some serious extinction. Now perhaps some people think I shouldn't believe these expectations and assume devastating GRB will occur much more frequently, perhaps once a day or once a week but right now these seem to be pretty good odds based on research. Another factor that works in our favor is that GRB's tend to be tightly collimated thus the odds of a earth shattering GRB would also depend on both the change of occurrence within our galaxy and the change that the earth would be within it's beam.

Yes, GRB's are detected with much greater frequency but the vast majority are generated in very distant galaxies and are of no threat to the earth.

And, as you said, in the improbable worst case scenario there is nothing we are going to do about it anyway.

Of course there is always the chance they are not GRB's at all but the angry fist of God so maybe we can pray them away.. ;)

[N1LAF]

It was recently found that the Earth was likely irradiated with gamma rays from a source in space in 774/775 AD.

For those who have said that these events do not happen, here is proof that it not only does, but it has. If it were closer, it would've "led to the extinction of some terrestrial life." Yes, all that life that was on surface of the Earth facing the event.

I don't know anyone here would dispute this would happen, but it appears that events like this a little more common than originally thought. From what I understand, the gamma ray burst is along the rotational axis of the source object. Interesting reading.

---- More interesting stuff ----------------

Betelgeuse : also known by its Bayer designation Alpha Orionis (α Orionis, α Ori), is the eighth-brightest star in the night sky and second-brightest in the constellation of Orion.

Distance 643 ± 146 ly

Betelgeuse is already old for its size class and is expected to explode relatively soon compared to its age. Solving the riddle of mass-loss will be the key to knowing when a supernova may occur, an event expected in the next million years. Professor J. Craig Wheeler of The University of Texas at Austin predicts Betelgeuse's demise will emit 1046 joules of neutrinos, which will pass through the star's hydrogen envelope in around an hour, then travel at light speed to reach the Solar System centuries later—providing the first evidence of the cataclysm. The supernova could brighten over a two-week period to an apparent magnitude of −12, outshining the Moon in the night sky and becoming easily visible in broad daylight. It would remain at that intensity for two to three months before rapidly dimming. Since its rotational axis is not pointed toward the Earth, Betelgeuse's supernova is unlikely to send a gamma ray burst in the direction of Earth large enough to damage ecosystems.
http://en.wikipedia.org/wiki/Betelgeuse