Astronomy Today

Gamma-Ray Space Telescopes

What has the Fermi gamma-ray telescope accomplished?

Aside from numerous interesting discoveries about the gamma-ray emissions from distant stars, galaxies, and black holes, astronomers using the Fermi telescope achieved a major mission goal in late 2012 when it computed the sum of starlight in the observable universe and the total amount of light produced by all the stars that have ever shone in cosmic history. This was done by measuring the amount of extragalactic background light in the cosmos—in a way, measuring the “thickness” of the “cosmic fog” that quenches gamma-ray light.


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