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阅读理解
Most maps show places you can visit and how
to get there. Most maps, however, were not made by astronomers. At a recent
meeting in Texas, three teams of these scientists presented new maps to show
where dark matter was.
Dark matter neither produces nor reflects
light, which means it's invisible (看不见) to human eyes and to most
scientific instruments. That makes it a challenge to measure and study. What
makes the matter more upset: Scientific measurements show that the universe
holds about five times as much dark matter as ordinary matter. Making up the
known part of the universe, ordinary matter includes you, your dog, Earth, the
sun, stars and planets.
Scientists find dark matter in the same
way, they discover other things we can't see by observing how the invisible
matter affects things we can see. We can't see wind, for example, but we can
feel a gentle wind or watch a windmill(风车)turning on a hill. Dark matter
doesn't turn windmills, but it does have gravity(引力). Like
ordinary matter, dark matter holds everything around it firmly with gravity. Dark
matter's gravity holds galaxies (星系) together and bends
rays of light as they move past.
To make the new maps, astronomers trained
powerful telescopes to watch for bending light arriving from distant galaxies. These
telescopes recorded light that came from galaxies billions of light-years away.
By studying how the light changed as it traveled through space, the astronomers
could work out the location and shape of dark matter groups.
One of the new maps shows dark matter is
more than 600 times as large as a full moon. The other covers an area more than
a thousand times as large. But that's just the beginning: The astronomers want
to carry on further studies to better understand the dark matter.
