Question

【题目】On a clear night, you can see a sky paced with stars. But you can’t see planets orbiting any of these stars, even with the strongest Earth—based telescopes. Astronomers reported that they discovered seven Earth—sized planets orbiting a nearby star called TRAPPIST – 1 in February. They had to rely on indirect evidence to tell them that the planets are there. By doing some math, they figured out the number of planets and the distance of their orbits.

TRAPPIST – 1 is a red dwarf （红矮星）, much smaller than our sun, but larger than Jupiter (木星). If the sun were the size of a basketball, TRAPPIST – 1would be the size of a gold ball. This star is one of our closest neighbors, just like the moon to the earth in space.

When astronomers using Earth-based telescopes to study TRAPPIST – 1,they noticed that every once in a while, it became slightly dim（昏暗）. They decided that a planet must be passing in front of the star, blocking part of the light. This dimming would come and go as the planet orbited the star, passing alternately (交替地) behind and in front of the star regularly.

By making careful observations, astronomers expected to get a rough idea of the planet’s size from the pattern of dimming light. But the light level changed often and not at evenly spaced (均匀间隔的) times. The astronomers had to conclude they were looking at more than one planet! To get additional data, NASA’s spritzer Space Telescope measured TRAPPIST –1’s brightness nearly continuously for 20 days, catching 34 crossings of planets in front of the star. Sorting through the mess of data, the astronomers found that the innermost planet completes its orbit in 1.5 Earth days, while the outermost planet takes 20 days. Once you know how long it takes each planet to complete an orbit, you can work out how far it is from the star compared with the other planets.

The TRAPPIST – 1 planets are not alone. So far, astronomers have found more than 3,400 planets that orbit other stars.

【1】How did astronomers know the number of planets orbiting TRAPPIST –1?

A. They used their eyes. B. They used telescopes.

C. They performed some calculation. D. They made some guess.

【2】How does the author introduce TRAPPIST – 1 in paragraph 2?

A. By giving examples. B. By making comparisons.

C. By providing research results. D. By listing some numbers.

【3】What probably causes the star TRAPPIST – 1 to be slightly dim?

A. The telescope’s failure. B. The cloud floating around.

C. The star’s moving. D. The passing planets.

【4】What’s the main idea of Paragraph 4?

A. The ways to get the information of the planets.

B. The introduction of the planets.

C. The distances of the planets to the star.

D. The astronomers’ effort of exploring TRAPPIST – 1.

Answer 1

【答案】

【1】C

【2】B

【3】D

【4】A

【解析】这是一篇说明文。本文主要介绍了天文学家发现的一颗恒星-TRAPPIST - 1。这是一个红矮星，比太阳小，木星大，是离我们最近的邻居之一。

【1】细节理解题。由文中第一段的By doing some math, they figured out the number of planets and the distance of their orbits.可知，天文学家们通过一些数学计算，统计出了行星的数量。故C选项正确。

【2】推理判断题。由第二段的If the sun were the size of a basketball, TRAPPIST – 1would be the size of a gold ball. 可知，作者把太阳比做篮球，把TRAPPIST – 1比做金球来告诉读者它的体重，所以这里用的是作比较的方法。故B选项正确。

【3】推理判断题。由文中第三段的 planet must be passing in front of the star, blocking part of the light. This dimming would come and go as the planet orbited the star, passing alternately (交替地) behind and in front of the star regularly.可知，当行星经过恒星时就会阻挡一些光线，也就是说经过的行星引起了TRAPPIST – 1 轻微的昏暗。D选项正确。

【4】段落大意题。根据文中第四段的astronomers expected to get a rough idea of the planet’s size from the pattern of dimming light. ，To get additional data,Sorting through the mess of data,可知，该段主要讲的是天文学家如何更多的获得行星的一些信息，也就是获取行星信息的一些方式。故A选项正确。