It is the largest and most detailed ever 3D map of the universe（宇宙）- and a journey back in time 11billion years. Scientists have studied the brightest objects in the sky to come up with the image of the universe they have ever made. Experts said looking at the image was similar to “looking at the moon through the clouds”.
But because the light took a long time to reach Earth it is also a window back to 11billion years ago when galaxies (星系) were first coming together and forming large clusters. Earlier such images had used galaxies to map the universe and were only able to go seven billion years back in time.
The map could find the answer to the puzzles of how the universe expanded and may give clues to the nature of dark energy. Scientists from the Sloan Digital Survey studied 14,000 quasars (类星体)powered by black holes. As the light from the quasars comes towards Earth it lights up clouds of intergalactic hydrogen (星系间氢气) gas that absorb (吸收)it as certain wavelengths(波长).This leads to a red image which is broken down by colors-red indicates areas where more gas has got through while blue areas have let less gas through. This irregular (不规则的) pattern of quasar light is known as the “Lyman-alpha forest”.
“Here , we are looking at intergalactic hydrogen gas, which blocks light,” said physicist Anze Slosar. “It's like looking at the moon through clouds ----you can see the shapes of the clouds by the moonlight that they block.”
She also compared it to an ice sample from Antarctica—by examining pieces of it you can work out what happened in the past. Anze said that the telescope they used would in the future allow them to “be able to measure how fast the universe was expanding 11 billion years ago with an accuracy of a couple of percent”.
33. How did scientists work out the 3D map of the universe?
A. By examining the dark hole in the sky.
B. By looking at the moon through the clouds.
C. By analyzing the brightest things in the sky.
D. By comparing the differences of samples of 11 billion years ago.
34. The underlined word “ clusters” in Paragraph 2 is closest in meaning to _____.
A. clouds B. groups C. glasses D. maps
35. What is the advantage of the present 3D map of the universe?
A. It helps to see the shapes of the clouds more clearly.
B. It is easy to judge how much gas gets through the clouds
C. It helps to study the universe more accurately further back in time.
D. It helps people to find the locations of different continents on Earth.