The sun isn’t the only light source behind that summer tan | Science News



Support credible science journalism.

Subscribe to Science News today.

Science Stats

The sun isn’t the only light source behind that summer tan

Tiny amount of ultraviolet light comes from the Big Bang and other stars, galaxies

2:30pm, September 20, 2016
Milky Way Galaxy

CATCHING SOME GALACTIC RAYS Galaxies, such as those in this image from the Paranal Observatory in Chile, are responsible for less than one-billionth of 1 percent of your suntan. The bright blue-white points of light in this picture are stars in the Milky Way; most other objects are galaxies.

Your summer suntan is almost entirely locally sourced. But a smidgen of that healthy glow hails not from the sun but from the ultraviolet light of nearby stars and other galaxies: less than one-billionth of 1 percent. Even photons lingering from the Big Bang contribute some: roughly 0.001 percent.

This article is available only to subscribing members. Join the Society today or Log in.

Get Science News headlines by e-mail.

More from this issue of Science News

From the Nature Index Paid Content