Suntan Is Cosmic, Comes From Sources Beyond The Galaxies
A study led by a team of international researchers showed that about ten trillionths of suntans come from sources beyond the galaxy. A suntan is a tiny fraction of light that is responsible in browning or darkening your skin.
The findings of the study were published in the Astrophysical Journal. The team measured the extragalactic background radiation that arrives on the planet Earth each day and night. This measurement goes from the far-ultraviolet to the far-infrared.
Professor Simon Driver, the lead author of the study from International Centre for Radio Astronomy Research explained that most of the photons of light hitting humans originate from the Sun, whether directly, scattered by the sky, or reflected off dust in the solar system. On the other hand, he further explained that humans are also bathed in radiation from beyond the galaxy, called the extragalactic background light. He added that these photons are minted in the cores of stars in distant galaxies, and from matter as it spirals into supermassive black holes, as noted by IFL Science.
Meanwhile, Professor Rogier Windhorst from Arizona State University stated that the Universe also comes with its own inbuilt protection as about half the energy coming from the ultraviolet light of galaxies is converted into a less damaging wavelength by dust grains. He further stated that galaxies themselves deliver us with a natural suntan lotion with an SPF of about two, according to ICRAR.
The researchers together with Professor Driver gauged the ambient radiation from the Universe, from a wide range of wavelengths by combining images from a flotilla of space telescopes. The research was collaborated by Arizona State University and Cardiff University and collected observations from NASA's Galaxy Evolution Explorer and Wide-field Infrared Survey Explorer Telescopes, the European Space Agency's Herschel space observatory, the Spitzer and Hubble space telescopes and Australia's Galaxy and Mass Assembly survey. This was achieved to make the most accurate measurements ever of the extragalactic background light.