Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

November 17, 1996

A Quasar in the Gamma-Ray Sky
Credit: EGRET team, Compton Observatory, NASA

Explanation: The bright object in the center of the false color image above is quasar 3C279 viewed in gamma-rays, photons with more than 40 million times the energy of visible light. Like all quasars, 3C279 is a nondescript, faint, starlike object in the visible sky. Yet, in June of 1991 a gamma-ray telescope onboard NASA's orbiting Compton Gamma Ray Observatory unexpectedly discovered that it was one of the brightest objects in the gamma-ray sky. Shortly after this image was recorded the quasar faded from view at gamma-ray energies. Astronomers are still trying to understand what causes these enigmatic objects to flare so violently. Another quasar, 3C273, is faintly visible above and to the right of center.

Tomorrow's picture: Unusual M82: The Cigar Galaxy

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
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