Cosmic rays revealed: Is this invisible, impactful force dangerous?

First discovered in 1912 by Austrian physicist Victor Hess, every day, trillions of cosmic rays of cosmic rays bombard the Earth. While this might sound alarming, most of them are prevented from reaching the Earth's surface by our planet's natural forcefield (its atmosphere and magnetic field).

However, in some cases, these rays collide with particles in the atmosphere, resulting in a shower of so-called "secondary particles" that can make it to the Earth's surface.

According to the University of Chicago, more than 90 percent of cosmic rays consist of hydrogen nuclei, which are single protons. About 9 percent are helium's atomic nuclei, and only 1 percent are the nuclei of heavy elements such as iron. These particles are known as "hadronic particles" since they consist of hadrons, such as protons and neutrons, made up of fundamental particles known as quarks.

What's more, they are not just interesting natural phenomena. Cosmic rays provide us with information about space and the universe. For example, they have helped scientists discover antimatter and the muon, the first evidence for subatomic particles beyond the proton, neutron, and electron.

Moreover, cosmic rays can give us insights into the chemical and physical constitution of the universe, how it has evolved, and what takes place around supermassive black holes and in the hearts of exploding stars.

It is also interesting to note that the term "cosmic ray" was coined by Robert Millikan in 1925, but they are more accurately called cosmic particles since they are not rays but tiny bits of matter. However, the original term is still widely used as a nod to the past.

Where do cosmic rays come from?

Scientists are still determining where they come from, but most agree that some detected on Earth originate from the Sun. However, we have detected particles which we believe come from other galaxies.

However, this isn't easy to work out as cosmic rays are charged particles traveling through the universe in all directions. For this reason, it is difficult to determine their exact origin because magnetic fields can redirect them as they travel through space. That said, we can gain insight into the forces required to accelerate these particles and infer their source by measuring their energies.

Scientists also now believe that cosmic rays are produced by various phenomena, including supernovas, supermassive black holes, highly magnetized neutron stars, and galaxy collisions.

What happens if cosmic rays hit the Earth?

Cosmic rays are believed to have various impacts on Earth, ranging from their influence on technological systems to potential effects on the Earth's atmosphere and climate. There is also some speculation that they may have played a role in the origins of life.

One of the most fascinating theories concerning cosmic rays is their potential impact on cloud formation. The theory proposes that cosmic rays may aid cloud nucleation by ionizing tiny particles in the Earth's atmosphere, which can then act as nuclei around which water vapor can condense, forming clouds.

If true, this process could potentially impact the Earth's climate, as clouds play a vital role in regulating the planet's temperature by reflecting sunlight into space.

Regarding the origins of life, cosmic rays, due to their high energy, could, in theory, induce chemical reactions by breaking molecular bonds and ionizing atoms and molecules. Cosmic rays may have helped create complex organic molecules like amino and nucleic acids from simpler compounds in early Earth's atmosphere or extraterrestrial environments such as comets and meteorites.

Additionally, cosmic rays may have impacted biological evolution by causing mutations in the genetic material of living organisms. However, this effect would have been just one of many factors influencing evolutionary processes. It is also important to note that the role of cosmic rays and the formation/evolution of life on Earth is highly speculative at this stage.

How powerful are cosmic rays?

Scientists have recently conducted investigations into cosmic rays, which are highlighted in a report by Space.com. They are examining a wide range of energies, from 10⁹ electron volts (eV) to an incredible 10²⁰ eV, to unravel the composition and origins of cosmic rays.

Julia Tjus, a professor of physics and astronomy at Ruhr University in Germany, advocates for using advanced 3D modeling techniques, along with precise measurements of neutrinos and photons that accompany cosmic rays, to better understand their origin and the mechanisms that propel them to such extraordinary energies.

Some of these cosmic rays exhibit energy levels that border on the unbelievable. The Smithsonian documented a notable instance on May 27, 2021. This event was observed by the Telescope Array collaboration in Utah, which utilized over 500 detectors to track the particles as they descended upon the Earth's surface.

The detectors, laid out in a square grid, span an expansive area of nearly 300 square miles (777 square kilometers) within the Utah desert, meticulously designed to capture such rare cosmic phenomena.

The data acquired during this event pinpointed a cosmic ray with an energy level of around 240 exa-electron volts (EeV; 101⁸ electron volts), translating to approximately 40 joules of energy. That's about the same amount of energy in a brick dropped on your toe from waist height but carried in a single subatomic particle!

Are cosmic rays dangerous to life?

Most cosmic rays are either deflected or neutralized by Earth's magnetic fields and atmosphere. A few of them reach the Earth's surface, but they are not more harmful than any other radiation we are regularly exposed to. Traveling at higher altitudes or taking plane rides exposes you to more of these rays.

It is possible that cosmic rays can sometimes cause computer crashes. But what about living things? What would happen if a cosmic ray(s) hits your body? Well, ignoring that most of your body is space (yes, you are mostly made of nothing), probably not much.

The Centers for Disease Control (CDC) states that cosmic radiation exposes the body to radiation in a way similar to how a medical X-ray does. In the U.S., the average annual dose due to cosmic radiation is 0.34 millisievert (34 millirem) per year. Not much, but this is not without risk.

In theory, when cosmic rays enter the human body, they could potentially ionize molecules within impacted cells, which, in turn, could potentially harm DNA and other crucial biological structures.

However, the small chance of this happening is offset by the human body being equipped with mechanisms to repair such damage, and the levels of cosmic rays on Earth's surface are generally low enough that the risk associated with these interactions is considered minimal under normal circumstances.

Nonetheless, the effects of cosmic rays become more significant for astronauts in space where the Earth's atmosphere provides no protection, leading to higher levels of exposure and an increased risk of radiation damage.

Are cosmic rays the same as solar storms?

In short, no. Cosmic rays and solar storms are distinct in their origins and characteristics despite being related phenomena in space weather.

We've already covered cosmic rays above, but solar storms are a different beast altogether. In a nutshell, solar storms are disturbances in space weather that originate primarily from our Sun (hence the name).

They can include phenomena such as solar flares, coronal mass ejections (CMEs), and solar energetic particle (SEP) events. These events release massive amounts of energy and matter from the Sun's atmosphere, increasing solar wind. The solar wind is a stream of charged particles emitted by the Sun, primarily electrons and protons.

The composition of cosmic rays primarily consists of high-energy protons and heavier nuclei, whereas solar storms comprise electrons, protons, and plasma. Both impacts on Earth's space environment can be hazardous for things like technology and, to a lesser extent, life. However, the sources, characteristics, and impact mechanisms are entirely different.

And that is your lot for today.

Cosmic rays, which possess immense energies and have origins that are still a mystery, are a challenging phenomenon that tests our understanding of the universe. Scientists are utilizing advanced technologies to study these particles, and with each discovery, we gain a deeper understanding of cosmic processes.

These findings offer valuable insights that help bridge the gap between theoretical physics and the realities of the cosmos.