Cosmic rays are high energy rays created by cosmic major events (explosion of supernovas, ejecting neutron stars, etc.). This is electrically charged particles whose speed can reach up to one third of the speed of light.
When these rays get into contact with the atoms of the atmosphere, causing showers of particles (protons, electrons, neutrons ...). These are neutrons erect problems.
They crossed the field easily as they move into the interstitial space between the atoms.
When - by chance - their track meets that of an atom, it is disintegrated, causing an issue (among others) of electrons.
These disturbances are adequate for changing the status of a bit in the memory of an electronic circuit.
The consequences can be:
Computer data alteration.
These disturbances can reach any type of electronics: computer, mobile phone, medical devices, power electronics (train, etc...).
At 10 kilometers of altitude, there are about 10000 neutrons that pass through each square centimeter, each hour. At sea level, is about 10 through each square centimeter per hour.
A CNRS researcher believes when using a laptop (in an airplane), there's a risk that the device goes down (each 5 hours).
The ever increasing miniaturization of circuits makes them more susceptible to this phenomenon, and the fact that we put in more and more in a single volume increases the probability of an error.
That is why manufacturers of hardware and software are trying to find solutions to counter this issue (silicon substrates insulation, systems error correcting (ECC) redundant circuits (duplicate or triplicate), etc..)
Example result: In 2003, elections in Belgium were performed simultaneously in a traditional and electronic fashion (count).
A difference of 4096 votes had been recorded. The experts could only attribute this difference to the cosmic rays.