An awful lot of photons

NASA Fermi 5 years gamma

Or, to be precise, 4×10^84 (that’s 4 with 84 zeros): the total amount of photons emitted by stars in the entire universe.

Clemson University scientists, relying on imagery from NASA’s Fermi Gamma-ray Space Telescope, claim for the first time to have measured all of the starlight ever generated throughout the history of the observable universe.

By the numbers: According to the new data, which was published in the journal Science on Friday, the number of photons — particles of visible light — emitted by stars amounts to 4 times 10 to the 84th power.