extra-galactic background light. tagged posts

This is an infographic explaining the fact that 10 trillionths of a suntan comes from beyond our galaxy. Credit: ICRAR/Dan Hutton

Lie on the beach this summer and your body will be bombarded by about sextillion photons of light per second.Most of these photons, originate from the Sun but a very small fraction have travelled across the Universe for billions of years before ending their existence when they collide with your skin. Astronomers have now accurately measured the light hitting Earth from outside our galaxy over a very broad wavelength range. The research looked at photons whose wavelengths vary from a fraction of a micron (damaging) to millimetres (harmless).

But radiation from outside the galaxy constitutes only ten trillionths of your suntan, so there is no immediate need for al...