英语听力:自然百科 已知的宇宙:外星生命 Alien_Contact-2(在线收听) |
Are we alone ?And it ties into all the big questions: how do we get here ? where are we going ?Are we a part of a bigger picture? But for the longest time ,the question was taboo to science .
Before the Mid-1990s ,it was considered somewhat embarassing to even address the question, because looking for alien life seems a little frighteningly close to science fiction .
For decades ,the farthest we got in looking for aliens was imagining them on the silver screen .(What is your name?) After all , alien life needs a hull, and we havn't even find a planet outside our own solar system .
Scientists in fact never talked about planets around other stars. There is no way to detect them. And so it was one of those domains of science that you couldn't answer and therefore you didn't talk about it.
Then in 1995, astronomers discovered a planet orbiting a star 50 light-years from earth. And since then they found hundreds more .
For the first time, in human history ,we realized that our sun with its 8 major planets that go around it, is just one type of a planetary system ,one example of billlions.
These discoveries are exciting ,but don't expect to dial up ET on these planets anytime soon .
Well ,it's been a spectacular ride in the last decade to find these planets ,most of them are giant planets.
Most of the worlds we found are gas giants which probably couldn't support life .
You can't stand on pneumas ,no hard surface,they are large balls of hydrogen and helium gas like Jupiter and Saturn .
We have found a few rocky planets with hard surfaces ,but they are many times more massive than earth ,and contain the most hostile environments you could ever imagine. One such planet, CoRoT-7b,orbits so close to its star that / surface temperatures reach as high as 3000 degrees .Sunlights here does not bring the sound of birds' song ,instead it's an Armageddon of volcanic explosions . |
原文地址:http://www.tingroom.com/lesson/zrbaike/2010/259282.html |