英语听力：探索发现 2014-07-20 BBC 地平线：陨石的真相-30

It came in in the daytime sky out of the Sun. Weve got telescopes looking out there for these objects, but they only work at night. Radar doesnt help either because to really use radar to find these objects above the atmosphere, you have to know exac

英语听力：探索发现 2014-07-23 BBC 地平线：陨石的真相-31

When you consider the Earths history stretching over billions of years, its clear that meteorite impacts, far from being unexpected, are just a normal part of the life cycle of our planet. But that is not how they seem to us. The Chebarkul meteorite

英语听力：探索发现 科学新发现：我们的大气层-11

The planet also began releasing oxygen, thanks to an ancient adoption of photosynthesis. A very ancestral primitive plant cell either engulfed or tried to digest or surrounded a cyanobaterium and instead of digesting it, it actually became an organ w

英语听力：2013-11-24 地平线：什么害死了我们的蜜蜂—2

They don't live very long on average just a few weeks in the summer time. But in that time they'll fly four or maybe five hundred miles in total. and here's the best part. They are the only insect to provide us with food in the form of liquid gold, h

英语听力：2013-09-18 地平线：黑洞吞噬—1

Nothing is more seductive than the unknown, nothing more compelling than a place of danger that lies beyond normal comprehension. Of all those places, perhaps the strangest of all are black holes. They are an exit point from the Universe, hidden trap

英语听力：2013-09-22 地平线：黑洞吞噬—2

High above your head, in the centre of our Milky Way Galaxy, a violent drama is about to unfold. Our super-massive black hole is getting ready to have dinner. As a gas cloud three times the size of the Earth, its caught in its gravitational hold. Acr

英语听力：2013-09-25 地平线：黑洞吞噬—3

Theres nothing anywhere near as extreme as a black hole. The disturbing truth about black holes is that there are boundary between the known universe and the place that would forever lie beyond the reach of science. They are in an anomaly of gravity

英语听力：2013-09-27 地平线：黑洞吞噬—4

But if watching matter tumble over the edge of a black hole might now be possible, it is only because of the efforts of a generation of astronomers to wrestle these dark dragons of the cosmos into the realms of scientific reality. As is often the cas

英语听力：2013-09-29 地平线：黑洞吞噬—5

But that is not the only surprise. People began to realize that these tiny star-like things or they looked like stars are actually putting out as much energy as a hundred of galaxies. And they didnt look like a galaxy at all. The paradox was how some

英语听力：2013-10-02 地平线：黑洞吞噬—6

The mystery of what could count for the quasars' extraordinary brightness was the hot topic in astronomy during the 1960s. As astronomers began to grapple with the new enigmatic objects that had been found by the radio telescopes, one astronomer, kee

英语听力：2013-10-04 地平线：黑洞吞噬—7

It suggested a baffling paradox that quasars are really shining black holes, capable of emitting the energy of entire galaxies. But Lynden-Bell then went further. I predicted that there would be these massive objects found in the nearby galaxies. He

英语听力：2013-10-06 地平线：黑洞吞噬—8

But if you look carefully, stars aren't spread smoothly across the whole sky. They are gathered together into a band that loops around the sky which we call the Milky Way. That bright strip across the sky with its extraordinary abundance of stars and

英语听力：2013-10-09 地平线：黑洞吞噬—9

At last, astronomers had a map of our galaxy. A panorama of the Milky Way, it would never be possible to see from Planet Earth. 27,000 light-years from our solar system is the centre of our galaxy. If we were ever going to have a chance of seeing a b

英语听力：2013-10-11 地平线：黑洞吞噬—10

It's like trying to pick out an individual inside the middle of a busy city, with lights and cars, and things happening all around them. But that wasn't the only problem. Vast, swirling clouds of dust and gas prevent visible light from the centre of

英语听力：探索发现 科学新发现：我们的大气层-1

In the empty blackness of space surrounded by hostile planets and freezing vacuum, planet Earth is an oasis of life. And all because of our protective cocoon of gas. This blanket of air shapes everything we see on Earth. It protects, insulates and su

英语听力：探索发现 科学新发现：我们的大气层-2

Our chemistry, our very nature, our metabolism is completely shaped by the atmosphere. To appreciate our atmosphere, well rise through its layers, travelling from the planets surface, miles up above mountains and the clouds, to the very edge of space

英语听力：探索发现 科学新发现：我们的大气层-3

My crew chief said, are you ready? I said, Im ready, lets go. It was a very smooth take-off and I started ascending up, up, up. 30 minutes after take-off, Kittinger reaches 29,000 feet, the middle of the troposphere. At this altitude, the air is so t

英语听力：探索发现 科学新发现：我们的大气层-4

Kittinger is in the mid stratosphere, a record 102,800 feet high. And it is now the time to make the long, swift journey down. When it came time for me to jump, I was ready to jump because I was heading back toward a more friendly environment, a frie

英语听力：探索发现 科学新发现：我们的大气层-5

英语听力,探索发现,科学新发The mission had been a stunning success: Kittinger skydiving record stands to this day. He takes his first deep breath of air with a new found appreciation for our atmosphere. It was relief to be back on the plan

英语听力：探索发现 科学新发现：我们的大气层-6

In contrast, Jupiter and Saturn are all atmosphere. Unlike Earth, Jupiter doesnt really have a solid surface that you could stand on and then have your head up in the atmosphere looking at the clouds. Its just a giant, giant gas ball. Only one other