雅思阅读 14: A Forecast of Rock Clouds（岩石云的天气预报）

改编自 Johns Hopkins University / Science（2026年5月）。雅思阅读 Section 3 难度，约 1050 词。 素材来源：https://www.sciencedaily.com/releases/2026/05/260527023212.htm

Reading Passage

A. Every morning on the giant exoplanet WASP-94A b, clouds made of rocky minerals gather across the sky. By evening, they have vanished. Observations from the James Webb Space Telescope (JWST), published in Science in May 2026, have captured this striking daily weather cycle on a world nearly 700 light-years from Earth. The findings mark one of the first times scientists have directly observed cloud formation and dissipation on a "hot Jupiter" — a gas giant orbiting so close to its star that surface temperatures exceed 1,000 degrees Celsius. "I've been looking at exoplanets for 20 years, and general cloudiness has been a thorn in our side," says co-author David Sing of Johns Hopkins University. "It's like trying to look at the planet through a foggy window. Not only have we cleared the view, but we can finally pin down what the clouds are made of." Hot Jupiters had long been the poster children for atmospheric puzzles. Because their skies are perpetually shrouded, even the most basic measurements — how heavy they are, what their air contains — kept coming back uncertain, leaving theorists to argue over models that no observation could settle.

B. WASP-94A b was discovered more than a decade ago, but earlier telescopes could only return an averaged picture of its atmosphere — cloudy and clear regions blended together, indistinguishable. JWST's advantage lies in its ability to separate the two sides of the planet during a transit. As the world crosses in front of its host star, the telescope can examine the leading edge of the disk — the planet's morning side, where atmospheric winds carry cool air from the night hemisphere toward the scorching dayside — and the trailing edge, the evening side where air flows back into darkness. The morning side, the data showed, was packed with clouds of magnesium silicate, a mineral common in Earth rocks. The evening side was almost entirely cloud-free. The trick was possible only because the planet's orbit is tilted so that it crosses the face of its star as seen from Earth. During each such transit, a sliver of starlight filters through the rim of the atmosphere on its way to the telescope; different wavelengths of that light betray different gases and suspended particles, allowing observers to map the cloud cover across the planet's limbs rather than over the disk as a single blended average.

C. Why do the clouds vanish? Two mechanisms are under investigation. The first holds that powerful winds on the dayside drag the mineral clouds deep into the atmosphere, hiding them from view. The second suggests that the clouds simply evaporate when they encounter temperatures above 1,000 degrees, much as morning fog burns away under a terrestrial sun — except on a vastly more extreme scale. "People have expected some differences," Sing remarks, "like it's cooler in the morning than the evening — that's something natural we experience here on Earth. But what we saw was a real dichotomy, huge differences in cloud coverage, and that changes our whole picture of the planet." The clearer evening skies also allowed researchers to peer directly at the atmosphere itself, correcting a long-standing misconception: earlier measurements had suggested the planet contained hundreds of times more oxygen and carbon than Jupiter, which conflicted with existing theories of giant-planet formation. The new data reduce that ratio to roughly five times — making WASP-94A b far more chemically similar to Jupiter than anyone had supposed. That correction matters because the balance of oxygen to carbon is a fingerprint of where and how a giant planet formed. A world born from icy material beyond the frost line should look broadly like Jupiter, whereas one assembled from a different mix might betray its origins with unusually oxygen-poor air. The earlier, inflated estimate had threatened to place WASP-94A b in a category of its own.

D. Hot Jupiters occupy a peculiar niche in planetary science. They orbit their stars closer than Mercury orbits the Sun, yet they are gas giants like Jupiter — a combination that should not, according to early theories of planetary formation, exist at all. Their existence forced astronomers to conclude that giant planets form beyond the "frost line" and then migrate inward, or form in situ under conditions that are still poorly understood. Because they are so hot, their atmospheres host chemical reactions that never occur on cold solar-system planets, making them natural laboratories for extreme atmospheric chemistry. The discovery of recurring cloud cycles on WASP-94A b provides a new tool: if clouds reliably appear and dissipate on a daily schedule, astronomers can observe the same atmosphere under both cloudy and clear conditions on successive orbits, effectively stripping away the obscuration that has hampered exoplanet spectroscopy for decades. Because they bake under their stars, hot Jupiters also experience winds and vertical mixing far more violent than anything in our own solar system, which means the physics learned on them does not always transfer directly. Yet it is precisely that ferocity that makes them useful: they stretch atmospheric models to extremes that can be reached nowhere closer to home.

E. The team has already begun applying the method to other hot Jupiters. Of eight additional worlds examined, two — WASP-39 b and WASP-17 b — showed similar morning-cloud, evening-clear patterns. The next phase, supported by a larger JWST observing programme, will extend the search to planets on eccentric orbits that carry them through the habitable zone, where temperatures might permit water clouds rather than rock vapour. The broader implication is that weather on distant worlds is not the uniform, static murk that early observations suggested. It is dynamic, seasonal, and — on the timescale of a planetary day — dramatically changeable. For a field that once struggled to detect even the presence of clouds, resolving a daily weather cycle is a step change in observational capability. The team cautions, however, that a handful of well-observed worlds cannot yet reveal how typical such cycles are. Many more transits, on planets with different masses, ages and orbits, will be needed before a general picture of hot-Jupiter weather emerges. Even so, the first daily forecast from another solar system already looks like something worth tuning in for.

Questions 1-4

Choose the correct heading for paragraphs B, C, D and E from the list of headings below.

List of Headings i. How JWST separates morning from evening ii. Why the clouds disappear and what the clear skies reveal iii. The history of exoplanet discoveries iv. Why hot Jupiters are useful natural laboratories v. Finding the same weather pattern on other worlds vi. How magnesium silicate is mined on Earth vii. The discovery of water clouds on Mars

1. Paragraph B: ____
2. Paragraph C: ____
3. Paragraph D: ____
4. Paragraph E: ____

Questions 5-8

Choose the correct letter, A, B, C or D.

5. What distinguishes JWST's observations from earlier telescopes? A. It can photograph the planet's surface directly. B. It can observe the morning and evening sides separately during transit. C. It measures the planet's mass more accurately. D. It orbits closer to WASP-94A b.

6. What are the morning clouds made of? A. Water ice, similar to Earth clouds. B. Magnesium silicate, a rocky mineral. C. Frozen carbon dioxide. D. Ammonia crystals.

7. How did the new observations revise earlier estimates? A. The planet has hundreds of times more oxygen than Jupiter. B. The planet's oxygen and carbon content is closer to Jupiter's than previously thought. C. The planet has no atmosphere at all. D. The planet is larger than previously measured.

8. Why are hot Jupiters scientifically valuable? A. They are the easiest planets to photograph. B. They host extreme atmospheric conditions that test chemical models. C. They contain liquid water. D. They orbit their stars in the habitable zone.

Questions 9-13

Do the following statements agree with the claims of the writer?

Write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

9. WASP-94A b is located about 700 light-years from Earth.
10. The clouds on the evening side are denser than on the morning side.
11. Earlier measurements suggested the planet contained about five times more oxygen than Jupiter.
12. Similar cloud cycles have been found on WASP-39 b and WASP-17 b.
13. JWST was launched in 2021.

Questions 14-15

Complete the summary below using NO MORE THAN TWO WORDS from the passage.

During a transit, JWST can observe the (14) __________ edge of the planet (morning) and the trailing edge (evening) separately. The morning side is cloudy, while the evening side is almost entirely (15) __________.

答案与解析

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