ALBUFEIRA
Um espelho que reflecte a vida, que passa por nós num segundo (espelho)
Matéria Negra
Matéria-Negra – Será que existe mesmo?
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Dark matter is mysteriously missing from the sun's neighborhood, according to a new study that could provide ammunition for skeptics who argue that the invisible substance is just an illusion.
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Even though dark matter particles can't be detected with current instruments, astronomers think the substance must make up about a quarter of the universe, based on the gravitational effect it has on visible matter such as galaxies and galaxy clusters.
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Current models of how galaxies form and rotate suggest that the Milky Way is embedded in a cloud, or halo, of dark matter. Astronomers can't tell precisely what shape this halo takes, but they expected to find significant amounts of dark matter in the region around the sun.
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Stars in the sky may appear static, but they're constantly in motion as they get minutely pushed and pulled by the gravitational effects of neighboring objects, including other stars, gas clouds, or clumps of dark matter.
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"These observations point to the fact that in this volume [of space], there is no dark matter".
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One reason scientists think dark matter exists is because stars in the outer parts of galaxies have been seen to orbit the center as fast as stars in the inner parts. The laws of gravity dictate that such fast-moving stars near the edges of galaxies should fly off into space. Instead, the theory goes, the added mass of dark matter holds them in place.
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(nationalgeographic.com)
