Two things about Earth are quite amazing: our atmosphere and Earth's magnetic field.
Earth has a solid iron and nickel inner core, surrounded by fluid iron nickel outer core. The motion of the fluid sets up a magnetic field that tends to deflect charged particles from outer space.
In particular, a great part of the Solar wind, solid matter thrown out by the Sun, is prevented from getting to the lower levels of our atmosphere.
Without the deflector shields, Earth might not be able to hold on to its atmosphere over billions of years: it would slowly be blasted away...
Currently, that's the explanation for Mars -- it used to have water and more of an atmosphere, but that's not what we see today.
Gamma rays don't go very far into our atmosphere before getting scattered or absorbed.
Radiation from the Sun is far brighter than any gamma ray burst from light years away. So far.
> Gamma rays don't go very far into our atmosphere before getting scattered or absorbed.
I think part of the "fear factor" is the idea of a much closer burst happening, dumping vastly more energy our way, which we would have no way to detect (since it travels at the speed of light), and which could instantly vaporize 1/2 of our planet's atmosphere, thanks to that absorption you mention (:
Personally, I feel like that makes it somehow less worrying, but different people are different.
Heat will increase loss of atmosphere, but vaporized isn't the right word.
The issue would not be losing even 25% of the atmosphere instead of close to 0.00% per year, but that boiling oceans, steam, and air will hit say 1000F on the size of the GRB and then over the next hours/days mix with the rest and end up with a average of 500F.
Even with that, I suspect many but not all species of life would be extinct. Anything that lives in the deep ocean might be mostly unimpacted.
Two things about Earth are quite amazing: our atmosphere and Earth's magnetic field.
Earth has a solid iron and nickel inner core, surrounded by fluid iron nickel outer core. The motion of the fluid sets up a magnetic field that tends to deflect charged particles from outer space.
In particular, a great part of the Solar wind, solid matter thrown out by the Sun, is prevented from getting to the lower levels of our atmosphere.
Without the deflector shields, Earth might not be able to hold on to its atmosphere over billions of years: it would slowly be blasted away...
Currently, that's the explanation for Mars -- it used to have water and more of an atmosphere, but that's not what we see today.
Gamma rays don't go very far into our atmosphere before getting scattered or absorbed.
Radiation from the Sun is far brighter than any gamma ray burst from light years away. So far.