Starship Asterisk*

APOD Robot wrote: ↑Tue Dec 05, 2023 5:05 am Energetic Particle Strikes the Earth

Explanation: It was one of the most energetic particles ever known to strike the Earth -- but where did it come from? Dubbed Amaterasu after the Shinto sun goddess, this particle, as do all cosmic rays that strike the Earth's atmosphere, caused an air shower of electrons, protons, and other elementary particles to spray down onto the Earth below. In the featured illustration, a cosmic ray air shower is pictured striking the Telescope Array in Utah, USA, which recorded the Amaterasu event in 2021 May. Cosmic ray air showers are common enough that you likely have been in a particle spray yourself, although you likely wouldn't have noticed. The origin of this energetic particle, likely the nucleus of an atom, remains a mystery in two ways. First, it is not known how any single particle or atomic nucleus can practically acquire so much energy, and second, attempts to trace the particle back to where it originated did not indicate any likely potential source.

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RocketRon wrote: ↑Tue Dec 05, 2023 6:25 am Do we know for certain that this was indeed a single high energy particle ?
And not a whole 'cohort' of particles - arriving together ??

Indeed, Photographing such an event is going to present some challenges

RocketRon wrote: ↑Tue Dec 05, 2023 6:25 am Do we know for certain that this was indeed a single high energy particle ?
And not a whole 'cohort' of particles - arriving together ??

Chris Peterson wrote: ↑Tue Dec 05, 2023 2:06 pm

RocketRon wrote: ↑Tue Dec 05, 2023 6:25 am Do we know for certain that this was indeed a single high energy particle ?
And not a whole 'cohort' of particles - arriving together ??

There is no mechanism by which a group of particles would travel together. And the particle shower caused by multiple low energy collisions would be completely different from that created by a single high energy particle.

https://en.wikipedia.org/wiki/Cosmic_ray wrote:Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light.

johnnydeep wrote: ↑Tue Dec 05, 2023 3:52 pm

Chris Peterson wrote: ↑Tue Dec 05, 2023 2:06 pm

RocketRon wrote: ↑Tue Dec 05, 2023 6:25 am Do we know for certain that this was indeed a single high energy particle ?
And not a whole 'cohort' of particles - arriving together ??

There is no mechanism by which a group of particles would travel together. And the particle shower caused by multiple low energy collisions would be completely different from that created by a single high energy particle.

So, no natural mechanism that could do for particles what a laser does for photons (sort of), or that a particle accelerator can do for protons?

Also, that unimpeachable source Wikipedia says:

https://en.wikipedia.org/wiki/Cosmic_ray wrote:Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light.

Chris Peterson wrote: ↑Tue Dec 05, 2023 4:05 pm

johnnydeep wrote: ↑Tue Dec 05, 2023 3:52 pm

Chris Peterson wrote: ↑Tue Dec 05, 2023 2:06 pm

There is no mechanism by which a group of particles would travel together. And the particle shower caused by multiple low energy collisions would be completely different from that created by a single high energy particle.

So, no natural mechanism that could do for particles what a laser does for photons (sort of), or that a particle accelerator can do for protons?

Also, that unimpeachable source Wikipedia says:

https://en.wikipedia.org/wiki/Cosmic_ray wrote:Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light.

If you take "cluster" to simply mean atoms, sure. Not groups of independent particles.

johnnydeep wrote: ↑Tue Dec 05, 2023 4:26 pm

Chris Peterson wrote: ↑Tue Dec 05, 2023 4:05 pm

johnnydeep wrote: ↑Tue Dec 05, 2023 3:52 pm

So, no natural mechanism that could do for particles what a laser does for photons (sort of), or that a particle accelerator can do for protons?

Also, that unimpeachable source Wikipedia says:

If you take "cluster" to simply mean atoms, sure. Not groups of independent particles.

Alright. I wasn't considering a nucleus as a cluster, but obviously it is, and was also thinking there might be other "cluster" possibilities. I suppose neutrons could travel together in a group since they don't repel each other, but since they have no charge, presumably it would also be difficult to accelerate them. Hmm, how IS a nucleus cosmic ray accelerated anyway?

https://www.auger.org/outreach/cosmic-rays/cosmic-ray-mystery wrote:Lower-energy cosmic ray particles that strike the earth come from within our own Milky Way Galaxy. They may originate, directly or indirectly, from the supernova icon info explosions that mark the deaths of many stars. These explosions throw out fast-moving magnetic fields which reflect charged particles. Cosmic ray nuclei gain energy when they collide with such a moving reflector. At a magnetic shock, where the magnetic field slows abruptly, particles can become trapped between two reflectors. Like a ping-pong ball caught between two converging paddles, the nuclei make many reflections, and the energy gained in each reflection grows as their energy increases. This "magnetic shock acceleration" model was first proposed by the great physicist Enrico Fermi as an explanation for the acceleration of most cosmic rays. The process has been observed in magnetic shocks in the solar wind that flows out from our sun, producing cosmic rays of modest energy. The stronger moving magnetic fields produced in supernova explosions could provide the energy for most other cosmic rays.

Rauf wrote: ↑Tue Dec 05, 2023 5:39 pm

johnnydeep wrote: ↑Tue Dec 05, 2023 4:26 pm

Chris Peterson wrote: ↑Tue Dec 05, 2023 4:05 pm
If you take "cluster" to simply mean atoms, sure. Not groups of independent particles.

Alright. I wasn't considering a nucleus as a cluster, but obviously it is, and was also thinking there might be other "cluster" possibilities. I suppose neutrons could travel together in a group since they don't repel each other, but since they have no charge, presumably it would also be difficult to accelerate them. Hmm, how IS a nucleus cosmic ray accelerated anyway?

I don't know. But, it says here:

https://www.auger.org/outreach/cosmic-rays/cosmic-ray-mystery wrote:Lower-energy cosmic ray particles that strike the earth come from within our own Milky Way Galaxy. They may originate, directly or indirectly, from the supernova icon info explosions that mark the deaths of many stars. These explosions throw out fast-moving magnetic fields which reflect charged particles. Cosmic ray nuclei gain energy when they collide with such a moving reflector. At a magnetic shock, where the magnetic field slows abruptly, particles can become trapped between two reflectors. Like a ping-pong ball caught between two converging paddles, the nuclei make many reflections, and the energy gained in each reflection grows as their energy increases. This "magnetic shock acceleration" model was first proposed by the great physicist Enrico Fermi as an explanation for the acceleration of most cosmic rays. The process has been observed in magnetic shocks in the solar wind that flows out from our sun, producing cosmic rays of modest energy. The stronger moving magnetic fields produced in supernova explosions could provide the energy for most other cosmic rays.

johnnydeep wrote: ↑Tue Dec 05, 2023 7:59 pm

Rauf wrote: ↑Tue Dec 05, 2023 5:39 pm

johnnydeep wrote: ↑Tue Dec 05, 2023 4:26 pm

Thanks, that's pretty interesting! I'm still not sure how an electrically neutral nuclei can be "reflected" though, except by kinetically impacting other particles. Unless that's just what is meant here, which could explain the paddle analogy. Guess I might have to (try to) actually read the paper.

Bird_Man wrote: ↑Tue Dec 05, 2023 11:13 pm

johnnydeep wrote: ↑Tue Dec 05, 2023 7:59 pm

Rauf wrote: ↑Tue Dec 05, 2023 5:39 pm

Thanks, that's pretty interesting! I'm still not sure how an electrically neutral nuclei can be "reflected" though, except by kinetically impacting other particles. Unless that's just what is meant here, which could explain the paddle analogy. Guess I might have to (try to) actually read the paper.

If cosmic rays are either electrons, nuclei, or individual protons, they would be either negatively or positively charged. Therefore easily reflected by the magnetic waves.

aneedham wrote: ↑Mon Dec 11, 2023 8:15 am Too many "likely"s in this article. Only the last one is used correctly, as an adjective.

aneedham wrote: ↑Mon Dec 11, 2023 8:15 am Too many "likely"s in this article. Only the last one is used correctly, as an adjective.

Chris Peterson wrote: ↑Mon Dec 11, 2023 3:33 pm

aneedham wrote: ↑Mon Dec 11, 2023 8:15 am Too many "likely"s in this article. Only the last one is used correctly, as an adjective.

I'd say the word has been used quite correctly throughout the caption. And likely most English language experts would agree with me!