Life behind the Stars

The northern lights, also known as the aurora borealis, are a light phenomenon that occur in the northern polar region. The aurora is caused by cosmic rays.

The rays causing the aurora borealis have also had a significant effect on the evolution of life on Earth, but they bear a threat. How do these rays impact our climate? And what are the consequences for life on Earth? We don't see or feel them and yet they surround us all the time. Particles from outer space constantly hurtle into our atmosphere. The low-energy cosmic rays of the sun produce one of the most beautiful natural phenomena on Earth: auroras. The aurora borealis or northern lights in the Northern Hemisphere and the aurora australis in the Southern Hemisphere light up the sky. As astrophysicist Pavel Motloch explains, "what happens to these cosmic rays depends on how much energy they carry. The low-energy rays coming from the Sun are mostly shielded from the Earth's magnetic field. So they follow the field lines of the magnetic fields up in the North and South Pole regions, where you can see them as the magnificent northern lights. But there are also the high-energy cosmic rays, which just go through the magnetic field and don't care about it at all." Most of them are protons, which generate immense energy as they accelerate. For decades, astrophysicists around the world have been puzzling over where these particles come from and how they generate so much energy. Cosmic rays can cause genetic changes, and biologists see them as an important factor in evolution - without them, the diversity of species we see today wouldn't exist. But cosmic rays would be deadly without protection. Fortunately, our planet has effective shields against the constant flow of particles from outer space in the form of a magnetic field and the Earth's atmosphere. Its magnetic field acts as a radiation blocker, and the Earth's atmosphere also absorbs a lot of the particles. In fact, only a small amount of radiation reaches the Earth's surface at all. Every 50 years a supernova explodes, flooding the Milky Way with cosmic rays. At the Pierre-Auger Observatory in Argentina, a groundbreaking international experiment is investigating ultra high-energy cosmic radiation. The filmmakers travel to research centers in Spain, Argentina and Switzerland to uncover its mysteries.

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