Gamma ray (noun, “GAH-muh RAY”)
Gamma rays are a type of electromagnetic radiation.
Electromagnetic radiation is a type of energy that travels through space in waves. Visible light and infrared light are both types of this radiation. So are radio waves and X-rays. And gamma rays are, too. In fact, gamma rays have the highest energies of any electromagnetic waves. Gamma rays also have the shortest wavelengths.
On Earth, high-energy events such as bolts of lightning and nuclear explosions give off gamma rays. The decay of radioactive materials, such as uranium, releases gamma rays as well. So does the fission inside nuclear power plants. Such high-energy rays can pass through the human body, damaging tissue as they go. But dense materials, such as lead, can block or slow gamma rays. And in very small doses, doctors can use gamma rays to kill diseased cells.
Objects throughout the universe throw off gamma rays. Pulsars and other neutron stars are some examples. Violent events, such as star collisions or explosions, shed gamma rays too. As do the chaotic regions swirling around black holes. Earth’s atmosphere shields us from this high-energy space radiation. But gamma ray detectors on mountaintops or orbiting Earth can see waves coming from across the cosmos.
In a sentence
If stars made of antimatter exist, they might give off a lot of gamma rays.