Description: Gamma ray photons are the most energetic photons in the electromagnetic spectrum, expressed by the Greek letter "γ". Gamma ray photons generally carry an energy greater than 100 kiloelectronvolts, greater than 50,000 times more energy than photons of visible light, and have frequencies of about 3x10¹⁹ hertz or greater, and wavelengths less than 10 picometers (1 picometer is 10^-12 m).

Gamma rays are emitted by the nuclei of some radionuclides after radioactive decay. In astronomy, gamma rays are emitted by the most extreme supernovae as gamma ray bursts, by active galactic nuclei such as blazars, and by solar flares.

Gamma rays emitted by astronomical sources do not reach the Earth's surface. Therefore, to study gamma rays, it is necessary to place detectors above the Earth's atmosphere.

Related Terms:

• Active Galactic Nucleus
• Electromagnetic Radiation
• Solar Flare
• Ultraviolet
• Gamma Ray Burst

Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

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