What Are Cosmic Rays?

Here’s a fun and highly mysterious topic to learn about: Cosmic Rays!

Cosmic rays are high energy particles, usually protons and electrons, which collide into our atmosphere and produce many more high energy particles like muons, pions, and photons. The particles that come from outer space are usually called primary cosmic rays, and the ones made in the atmosphere are called secondary cosmic rays. These particles are mostly charged, which is a pain for reasons we’re about to discuss.

Here’s an interesting diagram of how one event could occur. Credit: Javier Zarracina/Vox

These particles have such high energies that they’ll travel at relativistic speeds (close to the speed of light), and they often come from outside the solar system or even from other galaxies! That’s amazing because they’re one of the only things to visit us from outside the solar system.

A large portion of cosmic rays are protons and electrons, so most of these these particles are electrically charged and their paths can be altered by magnetic fields. The issue is, there are a whole lot of magnetic fields on the way to Earth, including our own one. As a result, cosmic rays have heavily altered paths which we struggle to figure out!

So how do we find out where they’re from?

The first thing to do is to figure out what has decided to visit us. We can do this with various particle detectors, such as proton detectors or Geiger tubes. Do we have nuclei like helium or even lead, with a sprinkle of electrons? Or is it mostly a bunch of protons? Even better still is measuring the amount of isotopes and charges. While this doesn’t help us trace the path that those specific rays took, we can get a good idea of where they could have come from in general.

Here’s UChicago’s TRACER detector after finishing its job and crashing! Credit: UCHIGACO & Stratocat.

Most astronomers agree that a lot of cosmic rays come from supernovae remnants in the galaxy. The supernova explosion creates heavy metals which are found in cosmic rays, and their magnetic fields can accelerate particles to high enough speeds to cross the galaxy.

That being said, supernovae remnants have the capability to accelerate particles to a certain energy, but we observe cosmic rays with far higher energies than is possible with a supernova. The origin of these extremely high energy rays are a huge mystery. Perhaps they’re quasars or AGN, or even Gamma Ray Bursts? It’s a great mystery!

But How is this Important to Us?

G299, Type 1a Supernova. Credit: NASA/CXC/U.TEXAS

Cosmic Rays are actually a huge problem to us. The electronics in our satellites and ground-based technology have advanced to work on such small scales that a high energy particle interfering with equipment can cause latchups, short circuiting and major faults.

Many of these single events are permanent and microelectronics can drain huge amount of power or have their memory wiped just like that!

We need to understand cosmic rays to better prepare our electronics so that we don’t get problems, and in fact we’re doing a great job at that already! Many techniques have been developed to “harden” microchips such as building circuits on a more electrically insulating form of silicon or simply shielding the circuits more with materials like boron.

Unfortunately many satellites are made by private companies, hence a lot of these techniques are patented and kept secret so I can’t go into much detail.

I understand that this isn’t the most interesting or pressing of topics to many, but it gives insight into how satellites and spacecraft are built and I would very much like to know what it takes to build a spacecraft. Plus, the future of space involves human spaceflight. Pretty much all of our electronics would need some sort of radiation protection then, which would change the way we use tech! What an amazing time!

In the meantime, I’m off to the Proxima Centauri b. If you need me, just call me on my Boron-Block Phone. It came with a 1cm thick Titanium phone case!


  1. The human beings also will require protection! Most medical research has been done in low orbit and below the Van Allen belts which do confer some protection I think. Apollo astronauts did have some symptoms indicative of being caused by cosmic radiation.
    Enjoying your blog, thanks

    Liked by 1 person

    • There are cases of extremely high powered primary rays, but the likelihood that a cosmic ray bumps into a particle in the atmosphere is highly probable, so naturally there’d be a lot of secondary particle detection. So, you’re still not wrong!

      Liked by 1 person

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