Glossary term: Gamma Ray

Also known as gamma radiation

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.

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

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".