Ten trillionths of our suntan comes from beyond our galaxy

Lie on the beach this summer and your body will be bombarded by about sextillion photons of light per second.
Most of these photons, or small packets of energy, 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.
In a new study, astronomers have 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, called the extra-galactic background light, constitutes only ten trillionths of your suntan.
While 10 billion photons a second might sound like a lot, researchers behind the study said we would have to bask in it for trillions of years before it caused any long-lasting damage.

https://www.sciencedaily.com/releases/2016/08/160811190751.htm?