What are cosmic rays? What are the dangers to people?

Cosmic rays exist almost anywhere in the universe, even on our planet. It is a stream of high-energy particles from space, consisting mostly of individual protons and nuclei of elements, but also electrons and photons, neutrinos, etc.

The sunlight we see every day is a cosmic ray that burns the skin over time, and the ultraviolet rays in sunlight can directly damage the surface tissues of the human body. But fortunately, the earth's atmosphere, especially the ozone layer, can well shield the sun's ultraviolet rays and some high-energy cosmic rays, which play a vital role in protecting us humans and other living species on earth.

However, it is because of the protection of the Earth's atmosphere and ozone layer that astronomers' observations of celestial events are compromised. On the Earth's surface, for example, cosmic high-energy rays from beyond the Sun are difficult to reach, to the detriment of scientists' astronomical research. However, relatively speaking, the high altitude of the Earth is less affected by interference than underground areas, so some astronomical observatories or optical telescopes will be built at high altitudes.

According to CCTV news and other media reports, good news came from the Haizishan High Altitude Cosmic Ray Observatory in Dacheng County, Sichuan Province. The station's Water Cherenkov Detector Array (WCDA) has been fully completed and put into scientific operation.

Mount Haizi is 4410 meters above sea level, higher than most astronomical observatories in the world. In addition to the high altitude, there are relatively many sunny days each year. In addition, this place is not far from the airport, which is convenient for the transportation of equipment and personnel. In addition to that, it provides stable electricity, communication, and water supply, and the local government strongly supports it, making it an ideal astronomical observatory.

According to Cao Zhen, a researcher at the Institute of High Energy of the Chinese Academy of Sciences, Lasso, China's newest generation of high-altitude cosmic ray observatory, which is the third generation of China's alpine cosmic ray laboratory and currently the highest, largest and most sensitive cosmic ray observatory in the world, will be located here.

The Lasso, currently under construction, is a 2040-acre high-altitude cosmic ray observatory with four detector arrays, including 5195 electromagnetic particle detectors, 1188 sub-wood detectors, 3000 water Cherenkov detector units, and 18 wide-angle Cherenkov telescopes. The four instruments are used together to detect various ray particle streams from the Universe in an all-round, multi-level, and deathless way.

Cao Zhen, who is also the chief scientist of the zipper observation project, said: "Cosmic rays, also known as 'galactic meteorites' or 'cosmic messengers', can convey some information about cosmic events. Because it is itself a material component of the cosmic celestial bodies, its situation and performance carry information about the evolution of celestial bodies and the origin of solar activity in the universe. It is an important way for human beings to explore the universe and a gateway to explore the Earth's space environment."

The completed Water Cherenkov Detector Array is dedicated to detecting low-energy cosmic rays, while the Electromagnetic Particle Detector Array and the Muon Detector Array are mainly used to detect cosmic rays of slightly higher energy, Cao Yu said. The Wide-Angle Cherenkov Telescope Array will measure the cosmic ray energy spectrum with high precision. They will provide scientists with the opportunity to observe the characteristics and origin of cosmic rays and analyze and study them precisely, and help scientists solve many mysteries about the origin of cosmic rays.

What are cosmic rays， What are the dangers to people? Reference： The latest generation of high-altitude cosmic ray observatory: Watching out for the "cosmic messenger"