In 1966 Kenneth Greisen, Vadim Kuzmin and Georgiy Zatsepin showed that high-energy charged particles (cosmic rays are mostly atomic nuclei, and thus positively charged) should be slowed by collisions with the photons of the cosmic microwave background (radiation left over from the Big Bang that permeates all space).

ECONOMIST: Cosmic rays: They came from outer space | The

Using the first completed section of the NOvA neutrino detector, scientists have begun collecting data from cosmic rays-particles produced by a constant rain of atomic nuclei falling on the Earth's atmosphere from space .

ENGADGET: NOvA neutrino detector captures cosmic rays in 3D, aims to unlock the mysteries of the universe

It will examine neutrons (the electrically neutral components of atomic nuclei) that are ejected from the lunar surface after being bombarded by cosmic rays (energetic particles that constantly streak through space).

ECONOMIST: Divining water