Cosmic rays: the fastest particles

Cosmic rays are particles moving at extremely high speed through space, originating from outside our scheme. they really reach the surface of earth intact, disintegrating into showers of lighter, lower-energy particles after colliding with gases within the upper atmosphere. Neverthless, by tracking the speed and distribution of those secondary particles (and using sattelite and balloon-based detectors), astronomers can discover a surprising amount about the properties of primary cosmic rays.

Mostly atomic nuclei of hydrogen and helium-the two lightest elements-with small amounts of heavier nuclei like lithium and beryllium, they fall under distinct categories. Most 'normal' cosmic rays travel at speeds of around 99 per cent of the speed of sunshine. Trillions of them bombard Earth every second and evidence suggests a big proportion were ejected from distant supernovas.

A much rarer population of ultra-high energy cosmic rays (UHERCRs), meanwhile, carry way more energy and travel at speeds a little fraction of a per cent below c itself. UHERCR sources seem to lie the identical direction as distant active galaxies, and a few astronomers believe they're created by fast-spinning supermassives black holes acting as natural particle acceerators.