雅思阅读 028 · Can We Stop Calling Exoplanets "Earth-like"?

改编自 Scientific American（Phil Plait, 2026）。题型：段落信息匹配 + T/F/NG + 填空。难度：较难（Passage 3，约 900 词）。

---

🎧 课文朗读音频（约 1 分钟）

正文 Passage

A. The problem with "Earth-like"

To date, astronomers have found more than 6,300 exoplanets orbiting other stars, with new entrants arriving practically every day. Many of these are so weird that they are difficult to imagine. The very first ones discovered were radiation-riddled worlds orbiting a pulsar — the burned-out stellar remnant of a catastrophic supernova explosion.

Each and every one we find is an additional data point in the grand scientific quest to understand how planets form. But there is a problem: the adjective "Earth-like" gets used frequently to describe exoplanets, but in my opinion, it has never been true.

B. Earth-sized is not Earth-like

At best, all we can say with confidence is that exoplanets are Earth-sized (roughly the same diameter as Earth) or Earth-mass (about the same weight as our planet), or both. The only other thing we really know is their distance from their host stars, which lets us determine how much starlight they receive — and that only gives us a vague idea of any exoplanet's temperature.

That is because the mix of gases in their atmosphere can wildly change a planet's surface temperature. Just look next door at Venus: it is slightly smaller and less massive than Earth and not that much closer to the sun, but its surface conditions are hot enough to melt lead, and it has a sky with a crushing pressure 90 times greater than Earth's.

C. The case of LHS 1140b

The latest chapter in this saga is the exoplanet LHS 1140b. Its host star is a dim red dwarf about 49 light-years from our sun. Astronomers discovered this world in 2017, and current measurements put it at 1.73 times Earth's size and 5.6 times our planet's mass. Despite its bulkier build, this gives LHS 1140b a density very similar to Earth's, which implies its composition is similar as well.

D. Does density mean habitability?

Well, this world is a mere 14 million kilometres from its host star — closer than Mercury is to the sun. Even though its star is faint and cool, the planet is still not likely to be a nice place for life as we know it. While it is technically in the star's habitable zone, without a rather potent greenhouse effect, LHS 1140b is likely much colder than Earth, well below the freezing point of water.

And it has a substantially higher surface gravity, about 1.8 times what we feel on Earth. Living there would be rough.

E. The atmosphere breakthrough

Remarkably, astronomers recently used NASA's James Webb Space Telescope to detect a clear signature of an atmosphere around LHS 1140b — the first time this has been achieved for a rocky world. The "smoking gun" was a whiff of helium leaking away from the planet into space. While this was a breakthrough discovery, it still does not tell us much about the atmosphere's overall composition or anything about the planet's surface conditions.

F. Why overpromising backfires

All in all, this planet could be somewhat similar to Earth, or it could be as alien as alien can be. We just do not know. But this did not prevent a proliferation of headlines calling it "Earth-like".

This may seem like a nitpick, but overpromising about "Earth-like" exoplanets can easily backfire, spreading disappointment and disillusionment among the general public. It is possible, even preferable, to show people just how much we know — and how much we still must learn — about the incredible diversity of exoplanets out there.

---

题目 Questions

Questions 1-5: Which paragraph mentions the following?

1. the example of Venus as Earth-sized but not Earth-like

2. LHS 1140b's density being similar to Earth's

3. the risk of public disappointment from overpromising

4. the first exoplanets found orbiting a pulsar

5. the detection of helium leaking from LHS 1140b

Questions 6-9: T/F/NG

6. Astronomers have found fewer than 1,000 exoplanets.

7. Exoplanet distance from its star tells us exactly what the temperature is.

8. LHS 1140b is closer to its star than Mercury is to the sun.

9. The James Webb telescope detected the full composition of LHS 1140b's atmosphere.

Questions 10-13: Complete the notes. Choose NO MORE THAN TWO WORDS.

• More than (10) ____________ exoplanets have been discovered.
• Venus has a crushing pressure (11) ____________ times greater than Earth's.
• LHS 1140b is (12) ____________ times Earth's size.
• The James Webb telescope detected a whiff of (13) ____________ leaking from LHS 1140b.

---

答案 Answers

题号	答案
1	B
2	C
3	F
4	A
5	E
6	FALSE（more than 6,300）
7	FALSE（vague idea only）
8	TRUE
9	FALSE（detected an atmosphere, not its full composition）
10	6,300
11	90
12	1.73
13	helium

---

核心词汇

exoplanet / Earth-like / star / red dwarf / habitable zone / atmosphere / gravity / density / helium / James Webb Space Telescope / pulsar / supernova / Venus / habitability