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For the first time ever, scientists using NASA's

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Fermi Gamma-ray Space Telescope have found the source of a high-energy neutrino

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from outside our galaxy. The neutrino came from the

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eruption of a supermassive black hole at the center of a type of galaxy called

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a blazar. The eruption jetted out particles moving near the speed of light.

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Collisions inside the jet produced

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gamma rays, the highest-energy form of light, and neutrinos,

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ghostly particles that rarely interact with matter.

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3.7 billion years later, they reached Earth.

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On September 22, 2017, a single

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high-energy neutrino struck an atom in a water molecule in the Antarctic ice.

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The crash produced a particle called a muon.

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It raced through the ice so fast it emitted a faint blue glow.

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When the muon reached the South Pole, it was tracked by the

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IceCube Neutrino Observatory. IceCube scientists found

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the original neutrino likely came from beyond our solar system.

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They alerted astronomers to be on the lookout for cosmic outbursts possibly 

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associated with it. NASA's Fermi Gamma-ray Space

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Telescope found the source, a blazar it had been watching for some time.

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When the neutrino arrived, Fermi saw the blazar

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was brighter than it had been over the previous decade.

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It's the first time a neutrino could be traced back to a black hole, or to any

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source beyond our immediate galactic neighborhood. And it's an important

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step forward for a growing field scientists call multimessenger astronomy,

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which combines light with new signals like gravitational waves

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and neutrinos, to provide new insights on the most

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extreme cosmic phenomena.

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[Music fades] NASA Astrophysics

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[Beeping]

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[Beeping]

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Goddard Space Flight Center www.nasa.gov/goddard