Space & Astronomy

Has your suntan come from another galaxy ?

By T.K. Randall
August 13, 2016

Image: Milky Way Galaxy Seen From Amphu Laptsa Base Camp
Credit: Pravin Mishra / CC BY-SA 4.0 (adapted) Astronomers in Australia have determined that the photons responsible for giving you a suntan do not all come from our own sun. A tiny fraction of them - ten-trillionths of the total number - actually originate from distant galaxies and black holes situated far beyond the Milky Way.

"Most of the photons of light hitting us originate from the Sun, whether directly, scattered by the sky, or reflected off dust in the Solar System," said lead author Professor Simon Driver."However, we're also bathed in radiation from beyond our galaxy, called the extra-galactic background light. These photons are minted in the cores of stars in distant galaxies, and from matter as it spirals into supermassive black holes."

While you can be safe in the knowledge that bathing in these intergalactic photons isn't likely to give you an intergalactic sunburn ( unless you sunbathe for several trillion years anyway ), the study does still highlight the need to use sunscreen when out on a hot day as our own sun will still be bombarding you with more than one sextillion photons per second.

That's enough to cause some pretty serious sunburn within a relatively short space of time.

Source: The Register

Tags: Galaxy, Suntan