Cosmic rays are generated by violent cosmic forces outside of our solar system, such as supernovas, quasars, galactic nuclei, and gamma-ray bursts. Cosmic rays primarily consist of ionized atoms, 9% of which are alpha particles, with 1% of cosmic rays being beta particles, both of which can penetrate into cells and cause damage to DNA and RNA which leads to mutations and cancer. Also, a small fraction of cosmic rays consists of anti-matter such as positrons and anti-protons, which instantly self-destruct when they encounter regular matter. Further, there are ultra-high energy cosmic rays such as the Oh-My-God particle, which is a single molecule that has the energy of a baseball moving at 56 mph.

However, most of the danger of cosmic rays comes from the air shower, which is a chain reaction and cascade of high energy particles caused by cosmic rays impacting air molecules in the atmosphere. Essentially, a cosmic ray particle will collide with an air particle, showering down X-Rays, alpha-particles, gamma rays, muons, protons, anti-matter, pions, beta-particles, and neutrons upon the Earth’s surface, especially at higher altitudes.

The sun’s magnetic field typically protects the Earth from most cosmic rays, but during solar minimum this protection weakens. Now the sun is in the deepest solar minimum since the space age began, causing the sun’s magnetic field to be at its weakest point in recorded history as well. This has resulted in record amounts of radiation showering down upon the Earth from cosmic rays.

A team of scientists and students in California regularly release high-altitude balloons to measure the radiation from cosmic rays, and finds that stratospheric radiation comprised of X-rays and gamma rays has increased 18% since 2015. This increase in radiation is continuing, simultaneous with the sun exhibiting a record amount of spotless days, indicating a historically deep solar minimum. Also, measurements of neutron fluxes in Finland, which is considered a good proxy for cosmic ray levels, are near record highs as well.

Radiation from cosmic rays are particularly a concern for astronauts in space. When the sun’s magnetic field is at its maximum an astronaut in a spaceship with proper aluminum shielding can stay in space for over 1,000 days before reaching the NASA-mandated radiation limit. Currently an astronaut can only spend about 200 days in a spaceship before reaching the radiation limit. This means that it is not safe to go on long space missions at this time, and especially unsafe to go on spacewalks outside of the spaceship.

Closer to home, cosmic rays cause dangerous amounts of radiation on commercial airliners, since at higher altitudes the radiation from cosmic rays is stronger. In-fact, the International Commission on Radiological Protection classifies pilots and flight attendants as occupational radiation workers due to cosmic rays. Even passengers who take just a single flight receive much more radiation than usual, which can potentially be carcinogenic.

The radiation from cosmic rays penetrates all the way to the ground as well, and although there have been no studies linking cosmic rays to cancer rates in the general population, basic logic would suggest that during this deep solar minimum that people on the ground are receiving more radiation than usual. There are studies which find that increased cosmic rays lead to more heart arrhythmias in the general population, proving that cosmic rays can impact health.

Although there is not much people on the ground can do to stay safe from cosmic rays, and the radiation dose rates are relatively low so it should not be something that people worry about, it is certainly interesting to note that carcinogenic radiation can come from interstellar and intergalactic sources. That being said, it is perhaps prudent to take less flights during times like these.