This article is about electromagnetic radiation. For the power metal band, see Gamma Ray (band)

Gamma rays (often denoted by the Greek letter gamma, γ) are an energetic form of electromagnetic radiation produced by radioactive decay or other nuclear or subatomic processes such as electron-positron annihilation.

Gamma rays form the highest-energy end of the electromagnetic spectrum. They are often defined to begin at an energy of 10 keV, a frequency of 2.42 EHz, or a wavelength of 124 pm, although electromagnetic radiation from around 10 keV to several hundred keV is also referred to as hard X-rays. It is important to note that there is no physical difference between gamma rays and X-rays of the same energy — they are two names for the same electromagnetic radiation, just as sunlight and moonlight are two names for visible light. Rather, gamma rays are distinguished from X-rays by their origin. Gamma ray is a term for high-energy electromagnetic radiation produced by nuclear transitions, while X-ray is a term for high-energy electromagnetic radiation produced by energy transitions due to accelerating electrons. Because it is possible for some electron transitions to be of higher energy than some nuclear transitions, there is an overlap between what we call low energy gamma rays and high energy X-rays.

More on [ Gamma ray ]

NPR Topics: Space

GeoEye-1 Will Be A High-Res Eye In The Sky
Fri, 29 Aug 2008 14:29:00 -0400
The GeoEye-1 satellite will be capable of making out details on Earth just 16 inches across. It will be the highest resolution satellite run by a private company; it's images will be marketed to a range of governments and private customers.
Europe Considers Joining Space-Faring Nations
Tue, 19 Aug 2008 10:35:00 -0400
Europe's space agency reached two milestones earlier this year. A European-built lab was installed at the International Space Station, and Europe launched a robotic cargo vehicle that successfully docked with the station. The European Space Agency is thinking about converting the vehicle so it could take astronauts into orbit.
Tensions With Russia May Hurt NASA Program
Fri, 15 Aug 2008 16:18:00 -0400
The conflict with Russia over Georgia might affect NASA's ability to get astronauts to the international space station after the space shuttle gets retired in 2010. Congress must pass a special waiver by Sept. 30 so NASA can buy Soyuz capsule flights.
What Makes Our Solar System Special?
Fri, 08 Aug 2008 15:02:00 -0400
Researchers say that if the conditions had been slightly different for our solar system, planets could have careened into the sun or been expelled into deep space. Also: A volunteer astronomer spots a strange gaseous object some are calling a "cosmic ghost."
Phoenix Finds A Salt Compound On Mars
Fri, 08 Aug 2008 14:07:00 -0400
NASA's Phoenix Mars Lander has detected a salt found on Earth on the surface of Mars. The salt, called perchlorate, is used in fireworks and rocket fuel. The news follows the recent confirmation of the presence of water on the Red Planet.
Space Company Hopes To Cut Cost Of Launches
Thu, 07 Aug 2008 16:44:00 -0400
A private company called SpaceX has failed three times to reach orbit with one of its rockets. But the company says it's learning from its failures and still hopes to radically decrease the cost of putting objects in space.

Subscribe to Astronomy RSS feed