Документальный фильм "600 Mysteries in the Night Sky"



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600 Mysteries in the Night Sky

600 Mysteries in the Night Sky.

Presented by Science at NASA.

The Universe is a big place, and there are a lot of things "out there" that astronomers can't identify. NASA's Fermi space telescope has just found about 600 examples. The Fermi team recently released the second catalog of gamma-ray sources detected by their satellite's Large Area Telescope. Of the 1873 sources found, nearly one-third are complete mysteries. No one knows what they are.

"Fermi sees gamma rays coming from directions in the sky where there are no obvious objects likely to produce this kind of radiation," says David Thompson, Fermi's Deputy Project Scientist. "It's a puzzle."

Gamma rays are by their very nature heralds of great energy and violence. They are a super-energetic form of light produced by sources such as black holes and massive exploding stars. Gamma-rays are so energetic that ordinary lenses and mirrors do not work. As a result, gamma-ray telescopes can't always get a sharp enough focus to determine exactly where the sources are. And therein lies the mystery.

For two thirds of the new catalog's sources the Fermi scientists can, with at least reasonable certainty, locate a known gamma ray-producing object such as a pulsar or blazar. But the remaining third, the "mystery sources", have the researchers stumped, at least for now. And they are the most tantalizing.

"Some of the mystery sources could be clouds of dark matter something that's never been seen before."

About 85% of the gravitational mass of the universe is dark matter. The stuff we see makes up the rest.

Dark matter is something that pulls on things with the force of its gravity but can't be detected in any other way. It doesn't shine, doesn't emit or scatter light - hence the name "dark" matter.

Astronomers are not able to detect dark matter directly using optical or radio telescopes. But dark matter just might shine in gamma rays.

"We've been using Fermi to search for dark matter for a long time," says the principal investigator for the Large Area Telescope, Peter Michelson of Stanford University.

Some researchers believe that when two dark matter antiparticles bump into each other, they will annihilate, producing gamma rays. Concentrated clouds of dark matter could form a gamma ray source at specific wavelengths detectable by Fermi.

"If we see a bump in the gamma-ray spectrum, a narrow spectral line at high energies corresponding to the energy of the annihilating particles - we could be the first to 'apprehend' dark matter," says Michelson.

So far, however, the team doesn't have enough data on the mystery sources to confirm or rule out the dark matter hypothesis. Other possibilities include undiscovered pulsars, supernova remnants, and colliding clusters of galaxies. The scientists plan to continue observing until they have some answers.

For more news about mysteries in space, dark and otherwise, visit Science.nasa.gov.

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Документальный фильм "600 Mysteries in the Night Sky"

















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