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.

2015 July 22

Gamma-ray Rain from 3C 279
Video Credit: NASA, DOE, International Fermi LAT Collaboration

Explanation: If gamma-rays were raindrops a flare from a supermassive black hole might look like this. Not so gently falling on the Fermi Gamma-ray Space Telescope from June 14 to June 16 the gamma-ray photons, with energies up to 50 billion electron volts, originated in active galaxy 3C 279 some 5 billion light-years away. Each gamma-ray "drop" is an expanding circle in the timelapse visualization, the color and maximum size determined by the gamma-ray's measured energy. Starting with a background drizzle, the sudden downpour that then trails off is the intense, high energy flare. The creative and calming presentation of the historically bright flare covers a 5 degree wide region of the gamma-ray sky centered on 3C 279.

Tomorrow's picture: comet trees

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