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托福考试知识点│关于宇宙中星云的话题

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发布时间:2018-10-29 杭州greenpath教育

你知道吗?你现在看到的星云,其实是他几万年前的模样~

晴朗的夜空里,分布着无数闪闪发光的星星,它们三五成群组成各式各样的图案,有的明亮有的暗淡,颜色也各不相同。壮丽的星空引起人们无限的遐想,激发人们去探索宇宙天体的奥秘。



在托福考试中我们常常会看到或者听到有关星空话题的考题。


Are we human because we gaze at the stars,or do we gaze at them because we are human?

                    ——《星尘》电影


我们今天来探索一下nebula。



在银河系中,有很多不同的星云,比如说猫爪星云,马头星云,女巫头星云等。


Stand outside on a clear night and look up. You’ll see that the stars are thicker along the Milky Way (shown above). 


Our galaxy looks like a fuzzy gray ribbon (灰色的丝带)of light across the sky. A low-power telescope(望远镜) shows that the Milky Way is actually made up of countless stars. They are too far away to be seen separately by the naked eye.


Astronomers have looked along the Milky Way with high-power telescopes for the last 200 years. They have found nebulae (星云)in many different colors and shapes. Spiral-shaped nebulae (星云)were later discovered to be whole distant cities of stars, called galaxies(银河系). Nebulae can tell us things about the evolution of stars. 


That’s because they are part of the birth and death of stars.


An emission nebula(发射星云)is a group of gases that glow. The Cat’s Paw Nebula (above) (猫掌星云)looks like a huge paw print on the sky. 猫掌星云,一系列的图片,各位铲屎官可以对比对比像不像猫掌。


The bright blobs are where clusters of young stars are blowing bubbles into the cloud. That makes the gases around them light up. They glow in shades of red, the color emitted by hot hydrogen gas(氢气).


星云不仅仅只有白色的,虽然在官方总称里它属于the milky way,最有意思的部分就是会有黑色的星云!Dark Nebula!有一种很酷的感觉,星际中的反派角色。


A dark nebula is a cloud of gas and dust that blocks the light from stars behind it. It can be seen only in silhouette (轮廓)(as a dark shape).


 The Horsehead Nebula (马头星云) (shown here) looks like a seahorse (海马)raising its head from a glowing ocean. The “ocean,” which is an emission nebula, is a shimmering (闪烁)sea of hydrogen. The red glow is from hydrogen gas behind the nebula. Bright spots at the base of the nebula are young stars forming.


A reflection nebula is made of dust that we can see only because light from nearby stars bounces off it. The Witch Head Nebula (女巫头星座)(left) glows mainly from light reflected by the bright star Rigel. (参宿七(猎户座星名))Rigel is in the Orion constellation(猎户星座).


 The nebula is blue partly because Rigel is blue. It’s also because the dust reflects blue light better than it reflects red light.


▲Planetary Nebula(行星状星云)


A planetary nebula is usually round. It looks like the disk of a planet when seen through a low-power telescope. It is actually an expanding blanket of gas around a dying star. To some, the Eskimo Nebula (above) looks like a person’s head surrounded by a parka. Planetary nebulae are the expanding remains of a star that is burning out.


When a massive star runs out of fuel, it explodes. It leaves behind a collection of newly formed elements. This leftover material is known as a supernova remnant. The blast itself is called a supernova. All elements heavier than iron are made in supernova explosions. The Crab Nebula (above) (蟹爪星云)was discovered in 1731.


It lies where a mysterious bright object briefly appeared in 1054. Astronomers later concluded that the Crab Nebula is the expanding debris from a star explosion in 1054.


In deep-space photographs, it looks like rose petals. The Trifid Nebula (above) gets its name from the dark lanes of dust that divide it into three (tri) pieces. 


The pink area is an emission nebula. The blue area is a reflection nebula. A bright cluster of stars lies in the center, lighting up the nebula.


浩瀚的星空中存在着各种各样的星云,希望大家能够多积累知识,在考场上所向睥睨!

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