Cosmic rays pummelling into Earth travel huge distances from alien galaxies

The most energetic cosmic rays that hit our planet come from far beyond our own galaxy, according to new research.

Cosmic rays pummelling into Earth travel huge distances from alien galaxies

Cosmic rays are the high-energy nuclei of atoms, from hydrogen to iron, that zoom around space. If humans come into contact with such radiation it can cause severe damage to the body, both in the short and long-term, and such particles pose a serious threat to astronauts travelling beyond our atmosphere.

On Earth, we’re protected from the majority of the particles because of the planet’s atmosphere and magnetic field. Only the most energetic can reach Earth, and even when they do, it is very rare. Plus, the origin of the most energetic cosmic ray particles has long been a mystery, until now.

In one of the most compelling research projects yet, published in Science, astronomers claim these particles travel to Earth from far beyond our galaxy.

“After more than a century since cosmic rays were first detected, this is the first truly significant result from our analysis of the detections, which now have revealed the distant origin of these ultra-high-energy cosmic rays,” says Miguel Mostafá, a professor at Penn State University.


“Now we know the highest-energy particles in the universe came from other galaxies in our cosmological neighborhood,” Mostafá says.

 Over 12 years, the researchers studied the direction from which the fastest-moving cosmic rays came towards our planet using the largest cosmic ray detector ever built, the Pierre Auger Observatory in Argentina.

They found the spread of particles was not even in all directions, meaning more rays come from sources in particular directions. More particles come from directions in which the concentration of galaxies is higher.

“We are now considerably closer to solving the mystery of where and how these extraordinary particles are produced, a question of great interest to astrophysicists,” says Karl-Heinz Kampert, professor of physics at the University of Wuppertal in Germany and spokesperson for the Pierre Auger Collaboration.

Understanding where these particles originate will help us to learn more about the origin of the universe, and in particular, our own solar system.

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