Gamma ray
![Illustration of an emission of a gamma ray (γ) from an atomic nucleusGamma rays are emitted during nuclear fission in nuclear explosions.](/Images/godic/202501/14/Gamma_Decay.svg5617.png")
![](/Images/godic/202501/14/Operation_Upshot-Knothole_-_Badger_0015617.jpg")
![This animation tracks several gamma rays through space and time, from their emission in the jet of a distant blazar to their arrival in Fermi's Large Area Telescope (LAT).](/Images/godic/202501/14/-NASA's_Fermi_Explores_the_Early_Universe.ogv5618.jpg")
![](/Images/godic/202501/14/NuclearReaction5618.png"){kind=spacer}
Gamma ray (also called gamma radiation), denoted by the lower-case Greek letter gamma (γ or ![\gamma](/Images/godic/202501/14/334de1ea38b615839e4ee6b65ee1b1035619.png")
), is extremely high-frequency electromagnetic radiation and therefore consists of high-energy photons. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays. Rutherford had previously discovered two other types of radioactive decay, which he named alpha and beta rays.