ICRAR: Ten Trillionths of Your Suntan Comes from Beyond Our Galaxy

[bystander]

Ten Trillionths of Your Suntan Comes from Beyond Our Galaxy
International Centre for Radio Astronomy Research (ICRAR) | 2016 Aug 11

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. ...

Where Your Summer Suntan Comes From:

• Sun:
  • 1x10²¹ photons per square metre per second
  Reflected off the sky:
  • 3x10²⁰ photons per square metre per second
  Leftover from the Big Bang:
  • 1x10¹⁶ photons per square metre per second
  Reflected off dust in the solar system:
  • 1x10¹⁴ photons per square metre per second
  Extragalactic background light:
  • 1x10¹⁰ photons per square metre per second

Extra-galactic background light measurements from the far-UV to the far-IR
from deep ground and space-based galaxy counts - Simon P. Driver et al

• arXiv.org > astro-ph > arXiv:1605.01523 > 05 May 2016

[neufer]

Ten Trillionths of Your Suntan Comes from Beyond Our Galaxy
International Centre for Radio Astronomy Research (ICRAR) | 2016 Aug 11

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. ...

Where Your Summer Suntan Comes From:

• Sun:
  • 1x10²¹ photons per square metre per second
  Reflected off the sky:
  • 3x10²⁰ photons per square metre per second
  Leftover from the Big Bang:
  • 1x10¹⁶ photons per square metre per second
  Reflected off dust in the solar system:
  • 1x10¹⁴ photons per square metre per second
  Extragalactic background light:
  • 1x10¹⁰ photons per square metre per second

My back of the envelope calculation shows the TOTAL # of photons as:

• Sun:
  • 1x10²² photons per square metre per second
  Black Body radiation off the ground (to compensate):
  • 2x10²³ photons per square metre per second
  Leftover from the Big Bang (~100 times colder than ground):
  • 2x10¹⁷ photons per square metre per second

I can sort of believe that perhaps 1 in 10 Solar photons are capable of producing a suntan.

But I can NOT believe that 1 in 20 Big Bang photons are capable of producing a suntan

• (Nor are 1 in 2 million Big Bang photons capable of producing a suntan.)