APOD: GRB 221009A (2022 Oct 15)

[johnnydeep]

So, these ultra high energy gamma rays passed over the Earth but were presumably blocked by the atmosphere, thereby protecting us hapless humans here on the surface. But these same rays also passed through (or impacted) satellites and the ISS and obviously also the orbiting Fermi telescope that detected tham. Is there a risk of damage to electronics or to human DNA for all the stuff in orbit? Also, how energetic would gamma rays have to be to be able to penetrate the Earth's atmosphere and reach the surface?

Worrying that we are going to be smote by a death star gamma ray burst from outer space is pointless. And unnecessary.
...

But this won't happen to us. You can rest easy.
...

Ann

So, again, why is it that these extremely high energy GRBs that we are currently detecting are not wiping out life on Earth, and apparently, not even disabling electronics in space? We, and everything on Earth, are obviously being "hit" by these super energetic photons, since I can't believe that only our detectors are getting hit! Is it simply because that even though the total energy of each photon is extremely high and therefore very dangerous, the total number of photons - the flux - is extremely low? Meaning, I guess, that we are not getting hit "directly", whatever that really means?

[Chris Peterson]

So, these ultra high energy gamma rays passed over the Earth but were presumably blocked by the atmosphere, thereby protecting us hapless humans here on the surface. But these same rays also passed through (or impacted) satellites and the ISS and obviously also the orbiting Fermi telescope that detected tham. Is there a risk of damage to electronics or to human DNA for all the stuff in orbit? Also, how energetic would gamma rays have to be to be able to penetrate the Earth's atmosphere and reach the surface?

Worrying that we are going to be smote by a death star gamma ray burst from outer space is pointless. And unnecessary.
...

But this won't happen to us. You can rest easy.
...

Ann

So, again, why is it that these extremely high energy GRBs that we are currently detecting are not wiping out life on Earth, and apparently, not even disabling electronics in space? We, and everything on Earth, are obviously being "hit" by these super energetic photons, since I can't believe that only our detectors are getting hit! Is it simply because that even though the total energy of each photon is extremely high and therefore very dangerous, the total number of photons - the flux - is extremely low? Meaning, I guess, that we are not getting hit "directly", whatever that really means?

This event was not particularly high energy, at only 10⁸ eV. It had a high intensity... that is what distinguished it. Gamma rays are largely blocked by our atmosphere, and satellites are hardened against them.

[Tingling sensation]

So THAT is why the dog started barking. I had checked the clock thinking it was my husband coming home early, and sure enough it was 2:10:17 pm UTC on the 9th.

"Trained to sniff out GRBs", they'd told me when I got that dog. Of course I didn't believe.

[johnnydeep]

Worrying that we are going to be smote by a death star gamma ray burst from outer space is pointless. And unnecessary.
...

But this won't happen to us. You can rest easy.
...

Ann

So, again, why is it that these extremely high energy GRBs that we are currently detecting are not wiping out life on Earth, and apparently, not even disabling electronics in space? We, and everything on Earth, are obviously being "hit" by these super energetic photons, since I can't believe that only our detectors are getting hit! Is it simply because that even though the total energy of each photon is extremely high and therefore very dangerous, the total number of photons - the flux - is extremely low? Meaning, I guess, that we are not getting hit "directly", whatever that really means?

This event was not particularly high energy, at only 10⁸ eV. It had a high intensity... that is what distinguished it. Gamma rays are largely blocked by our atmosphere, and satellites are hardened against them.

So, is intensity just the number of photons passing through a unit area per second (perhaps also combined with the energy of the photons)? At what intensity do gamma rays become a problem for life on earth? Is 1 peta eV photon per square mm per second deadly?

[Chris Peterson]

So, again, why is it that these extremely high energy GRBs that we are currently detecting are not wiping out life on Earth, and apparently, not even disabling electronics in space? We, and everything on Earth, are obviously being "hit" by these super energetic photons, since I can't believe that only our detectors are getting hit! Is it simply because that even though the total energy of each photon is extremely high and therefore very dangerous, the total number of photons - the flux - is extremely low? Meaning, I guess, that we are not getting hit "directly", whatever that really means?

This event was not particularly high energy, at only 10⁸ eV. It had a high intensity... that is what distinguished it. Gamma rays are largely blocked by our atmosphere, and satellites are hardened against them.

So, is intensity just the number of photons passing through a unit area per second (perhaps also combined with the energy of the photons)? At what intensity do gamma rays become a problem for life on earth? Is 1 peta eV photon per square mm per second deadly?

Intensity is just flux, yes. The energy of the photons is irrelevant. I'm not sure you could achieve a realistically high gamma ray intensity for it to be a problem. Really high energy gamma rays and cosmic rays might be 10¹⁹ eV or more. That is about the same kinetic energy as being hit by a baseball. One of those passes through you, it could do some real damage. Fortunately, such photons are very rare (which is another way of saying their intensity is very low).

[johnnydeep]

This event was not particularly high energy, at only 10⁸ eV. It had a high intensity... that is what distinguished it. Gamma rays are largely blocked by our atmosphere, and satellites are hardened against them.

So, is intensity just the number of photons passing through a unit area per second (perhaps also combined with the energy of the photons)? At what intensity do gamma rays become a problem for life on earth? Is 1 peta eV photon per square mm per second deadly?

Intensity is just flux, yes. The energy of the photons is irrelevant. I'm not sure you could achieve a realistically high gamma ray intensity for it to be a problem. Really high energy gamma rays and cosmic rays might be 10¹⁹ eV or more. That is about the same kinetic energy as being hit by a baseball. One of those passes through you, it could do some real damage. Fortunately, such photons are very rare (which is another way of saying their intensity is very low).

So why do I see articles about the possibility of Earth life being wiped out by a nearby supernova? Would that be due to something other than very high energy photons? Or are those articles simply erroneous?

[Chris Peterson]

So, is intensity just the number of photons passing through a unit area per second (perhaps also combined with the energy of the photons)? At what intensity do gamma rays become a problem for life on earth? Is 1 peta eV photon per square mm per second deadly?

Intensity is just flux, yes. The energy of the photons is irrelevant. I'm not sure you could achieve a realistically high gamma ray intensity for it to be a problem. Really high energy gamma rays and cosmic rays might be 10¹⁹ eV or more. That is about the same kinetic energy as being hit by a baseball. One of those passes through you, it could do some real damage. Fortunately, such photons are very rare (which is another way of saying their intensity is very low).

So why do I see articles about the possibility of Earth life being wiped out by a nearby supernova? Would that be due to something other than very high energy photons? Or are those articles simply erroneous?

There are two issues. The first involves being hit with an intense gamma ray beam (which reaches us at the speed of light). This can (and has) alter our atmosphere, especially by reducing the protective ozone layer, which can have significant consequences on our biosystems. It isn't going to result in destroying all life on Earth. The second is the stream of charged particles that arrives more slowly. These can be much more energetic, and can descend deeper into the atmosphere. They also release showers of other potentially damaging particles and photons as they collide with gas in the atmosphere. Again, we have the real possibility of significant biological impacts. But a supernova would have to be very, very close and very specially aligned to sterilize our planet.

[johnnydeep]

Intensity is just flux, yes. The energy of the photons is irrelevant. I'm not sure you could achieve a realistically high gamma ray intensity for it to be a problem. Really high energy gamma rays and cosmic rays might be 10¹⁹ eV or more. That is about the same kinetic energy as being hit by a baseball. One of those passes through you, it could do some real damage. Fortunately, such photons are very rare (which is another way of saying their intensity is very low).

So why do I see articles about the possibility of Earth life being wiped out by a nearby supernova? Would that be due to something other than very high energy photons? Or are those articles simply erroneous?

There are two issues. The first involves being hit with an intense gamma ray beam (which reaches us at the speed of light). This can (and has) alter our atmosphere, especially by reducing the protective ozone layer, which can have significant consequences on our biosystems. It isn't going to result in destroying all life on Earth. The second is the stream of charged particles that arrives more slowly. These can be much more energetic, and can descend deeper into the atmosphere. They also release showers of other potentially damaging particles and photons as they collide with gas in the atmosphere. Again, we have the real possibility of significant biological impacts. But a supernova would have to be very, very close and very specially aligned to sterilize our planet.

Thanks. So Ann was essentially correct in her reply to me above.

[johnnydeep]

So, this GRB seems to have actually generated electrical currents in the Earth's crust! I thought the atmosphere protected us from GRBs' effects down here? See https://spaceweatherarchive.com/2022/10 ... the-earth/

[Chris Peterson]

So, this GRB seems to have actually generated electrical currents in the Earth's crust! I thought the atmosphere protected us from GRBs' effects down here? See https://spaceweatherarchive.com/2022/10 ... the-earth/

The atmosphere protects us from the gamma rays. This is a secondary effect caused by the gamma rays ionizing the upper atmosphere. Totally harmless to life.

[johnnydeep]

So, this GRB seems to have actually generated electrical currents in the Earth's crust! I thought the atmosphere protected us from GRBs' effects down here? See https://spaceweatherarchive.com/2022/10 ... the-earth/

The atmosphere protects us from the gamma rays. This is a secondary effect caused by the gamma rays ionizing the upper atmosphere. Totally harmless to life.

Thanks. Yet another subtle physical effect I don't really understand. <sigh>

[VictorBorun]

So, this GRB seems to have actually generated electrical currents in the Earth's crust! I thought the atmosphere protected us from GRBs' effects down here? See https://spaceweatherarchive.com/2022/10 ... the-earth/

The atmosphere protects us from the gamma rays. This is a secondary effect caused by the gamma rays ionizing the upper atmosphere. Totally harmless to life.

Thanks. Yet another subtle physical effect I don't really understand. <sigh>

I would not feel protected. Every heavy particle with mass like 100 MeV does get intercepted by the air but the shower of the fragments falls upon us and it's ionizing radiation.


How strong is the air protection?
The atmospheric pressure at sea level equals to 10 meters of water column.
It's about the layer of water they use over fuel rods for a stage storing at a nuclear power station.
Better than nothing but cosmic rays particles from a gamma burst are heavier and more penetrating.

[Chris Peterson]

The atmosphere protects us from the gamma rays. This is a secondary effect caused by the gamma rays ionizing the upper atmosphere. Totally harmless to life.

Thanks. Yet another subtle physical effect I don't really understand. <sigh>

I would not feel protected. Every heavy particle with mass like 100 MeV does get intercepted by the air but the shower of the fragments falls upon us and it's ionizing radiation.

Yes, but we're not talking heavy particles here. These are gamma rays. Photons. They don't produce showers of secondary particles.