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600 mysteries in the night sky presented

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by science at nasa

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the universe is a big place and there

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are a lot of things out there that

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astronomers can't identify nasa's fermi

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space telescope has just found about 600

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examples

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the fermi team recently released the

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second catalog of gamma-ray sources

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detected by their satellite's large area

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telescope

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of the 1807

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sources found nearly one-third are

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complete mysteries

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no one knows what they are

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fermi sees gamma rays coming from

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directions in the sky where there are no

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obvious objects likely to produce this

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kind of radiation says david thompson

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fermi's deputy project scientist

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it's a puzzle

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gamma rays are by their very nature

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heralds of great energy and violence

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they are a super energetic form of light

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produced by sources such as black holes

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and massive exploding stars

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gamma rays are so energetic that

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ordinary lenses and mirrors do not work

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as a result gamma-ray telescopes can't

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always get a sharp enough focus to

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determine exactly where the sources are

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and therein lies the mystery

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for two-thirds of the new catalog

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sources the fermi scientists can with at

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least reasonable certainty locate a

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known gamma-ray-producing object such as

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a pulsar or blazar but the remaining

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third the mystery sources have the

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researchers stumped at least for now and

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they are the most tantalizing

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some of the mystery sources could be

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clouds of dark matter something that's

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never been seen before

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about 85 percent of the gravitational

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mass of the universe is dark matter the

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stuff we see makes up the rest

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dark matter is something that pulls on

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things with the force of its gravity but

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can't be detected in any other way

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it doesn't shine doesn't emit or scatter

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light hence the name dark matter

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astronomers are not able to detect dark

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matter directly using optical or radio

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telescopes but dark matter just might

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shine in gamma rays

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we've been using fermi to search for

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dark matter for a long time says the

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principal investigator for the large

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area telescope peter michelson of

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stanford university

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some researchers believe that when two

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dark matter antiparticles bump into each

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other they will annihilate producing

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gamma rays

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concentrated clouds of dark matter could

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form a gamma ray source at specific

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wavelengths detectable by fermi

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if we see a bump in the gamma ray

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spectrum a narrow spectral line at high

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energies corresponding to the energy of

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the annihilating particles we could be

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the first to apprehend dark matter says

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michelson so far however the team

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doesn't have enough data on the mystery

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sources to confirm or rule out the dark

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matter hypothesis

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other possibilities include undiscovered

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pulsars supernova remnants and colliding

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clusters of galaxies

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the scientists plan to continue

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observing until they have some answers

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