专业英语八级（阅读）模拟试卷174 (题后含答案及解析)
题型有：1.3 and three times as much as Earth and orbits its parent star once every 11 days. This puts its distance from Proxima Centauri itlf at 7m kilometres, which is less than a twentieth of the distance between Earth and the sun. It can remain temperate in such a clo orbit only becau Proxima is a red dwarf, and thus much cooler than the sun. It is not the only Earth-sized extrasolar planet known to orbit in a star’s habitable zone. There are about a dozen others. But it is the clost to Earth—so clo, at four light-years, that it is merely outrageous, not utterly absurd, to believe a spaceship (admittedly a tiny one) might be nt to visit it. Before this happens, though, it will be subjected to inten scrutiny from Earth itlf. (4) That scrutiny will probably be led by ESO. The data which led to Proxima Centauri b’s discovery came from the obrvatory’s 3.6 metre telescope at La Silla, in Chile. But ESO is also building a much bigger device, the 39-metre European Extremely Large Telescope (EELT), at another site in Chile. Since the late 2000s Markus Kasper of ESO has led a team which is designing a specialid planet-spotting instrument, the Exoplanet Imaging Camera and Spectrograph (EPICS), to fit on this telescope. Dr. Kas
per惊’s camera has a price tag of 50m ($ 56m), and there have always been questions about whether it is worth the money. But EPICS stands a better chance of producing actual pictures of Proxima Centauri b, and being able to analy its atmosphere, than any other instrument in the world (or off it). Its future can now scarcely be in doubt. (5) The problem for astronomers trying to catch a glimp of Proxima Centauri b is that, though clo to the Earth by interstellar standards, it is clor to its parent star by more or less every other standard short of that of walking down the road to the chemist. Seen from Earth, star and planet are 35 thousandths of an arc cond apart (an arc cond is a 3,600th of a degree). Producing a picture that parates the two objects thus requires a telescope with a resolution good enough to distinguish between the left and right headlights of an oncoming car in Denver from the distance of Berlin. (6) Things get wor. Dim as it is, Proxima Centauriis still more than 10m times brighter than its planet is expected to be. It is as though one of tho headlights in Denver was actually the open door to a furnace, while the other was a tea light. This is what makes the E-ELT and EPICS crucial. EPICS contains a coronagraph—a tiny shield that blocks out a star’s light
so that adjacent planets can be en. Unfortunately, a coronagraph reduces a telescope’般阳s resolution, meaning you need an even bigger one to e the target in the first place. To obrve Proxima Centauri b using a coronagraph, and doing so in the infrared wavelengths that are likely to provide the best information about its atmosphere, you need a telescope at least 20 metres across; 30 metres would be better. (7) The exciting thing about the planet奥特曼简笔画图片大全’绝句绝句s spectrum, however it is measured, is that it might reveal the water content and chemical composition of Proxima Centauri b’手脱皮是怎么回事s atmosphere, if it has one. And that might, in turn, give a clue as to whether it harbours life. Life on Earth leaves a sign of its existence in the atmosphere, in the form of oxygen. This is produced by plants and it is such a reactive chemical that if their photosynthesis stopped it would disappear rapidly from the air. Free oxygen in Proxima Centauri b’s atmosphere would therefore get a lot of people excited—but possibly without justification, for there are ways to put oxygen into atmospheres abiotically. A stronger indicator of life would be finding both oxygen and molecules associated with biology that cannot long persist in its prence, and must thus be produced continuously. (8) Another way to look for life on Pr
德少一横念什么oxima Centauri b would be to arch for radio signals. Life in general does not generate radiation at radio frequencies. But intelligent life does—at least it does on Earth. And that Earth-bound life also puts a tiny bit of effort into looking for such emissions from elwhere, an endeavour known as the arch for extraterrestrial intelligence, or SETI. There have been SETI studies of Proxima Centauri in past decades, but they have not been particularly nsitive. (9) That there is intelligent life in the nearest planetary system to Earth’s is surely the longest of shots. And despite its nice-sounding location in the “habitable zone”学弈文言文 , the prence of any sort of life on Proxima Centauri b is far from a foregone conclusion. For one thing, there are doubts about how easy it is for planets around red dwarfs to develop and retain atmospheres. Though such stars are cool for most of their existences, in their early years they burn bright. A planet clo enough to one to stay warm in later life might have en its atmosphere burned off in the star’s brief blazing youth. Even if it avoids this problem, it will still be whipped by the star’s magnetic field and lashed by its flares. Though they are dim, red dwarfs are given to all sorts of eruptive activity and pump out X-rays at a prodigious rate. The are both things which might make an atmosphere hard to hold on to and life itlf a bit tricky.列检
