英语听力：自然百科 黄石公园的夏天 Yellowstone—1

For six months, Yellowstone endures an unrelenting winter. An ice world of hunters and hunted. But now footsteps on the slopes of a mountain herald a change in the season. The sun regains its strength.Water flows again. The race begins to recover win

英语听力：自然百科 行星旅行：土星 Saturn—19

The Prime Meridian(本初子午线) here is the longitude, the mark on the ground, from which all great voyages are measured. This is the view back to our remarkable home planet/ that the first human out here can look forward to, a distant blue dot l

英语听力：自然百科 行星旅行：土星 Saturn—18

Breathing from a so-dubbed scuba unit and now fitted in a cross between a super ski suit and a haz-mat coverall, future Titannauts could explore with confidence. You just need that thermal protection and oxygen, and then you can play on the surface a

英语听力：自然百科 黄石公园的夏天 Yellowstone—11

The living is easy. But it won't last long. At this altitude, the air is so dry that rain evaporates before it even hits the ground. The water that flows off the plateau is no longer being replaced. Already there is drought in forests beyond the mead

英语听力：自然百科 行星旅行：土星 Saturn—5

With Saturn's 62 known moons, Cassini finds itself in good company without of this world photo opportunity to make even a seething professional gasp. Saturn is the most photogenic planet in all the solar system, so I just, you know, I mean, you could

英语听力：自然百科 行星旅行：土星 Saturn—2

Imagine boarding a flight to Saturn, what would you need to know before traveling? The best ringside vantage points? The must-see moons? Think of this as your personal guide to the splendor of the Saturnian system. A wandering spot of light twice as

英语听力：自然百科 行星旅行：土星 Saturn—3

Saturn might be the second largest planet in the solar system, but like gas giant neighbor Jupiter, its a triumph of show over substance. Saturn, first of all is a big giant gas ball, actually its a big giant ball of fluid, and the outer parts of it

英语听力：自然百科 行星旅行：土星 Saturn—4

Hopes and dreams of thousands of scientists and engineers are resting on the next few moments. Weve been to Saturn twice before with the voyager I and voyager II spacecraft. But rather than these quick Kodak moments, we want to take a nice long leisu

英语听力：自然百科 行星旅行：土星 Saturn—16

The by-product of billions of years of production from the chemical smog factory in the upper atmosphere, the grains in Titan's dunes may literally fall from the sky. Like a rain of flash-frozen coffee grounds, they are swept by the wind into deep pi

英语听力：自然百科 行星旅行：土星 Saturn—15

Huygens landed on Titan. It/ sent back these few hundred pictures, until the batteries died and the probe froze solid. The probe landed with a thud, on basically a streambed，an area/ littered with rounded cobbles, and showed that these little rocks

英语听力：自然百科 行星旅行：土星 Saturn—13

Planet earth never attempted to land on such a distant world before. With Huygens probe on final approach to Titan, operations switch to European mission control. The probe hurtled into Titans atmosphere at 6km a second, the atmosphere would have bee

英语听力：自然百科 行星旅行：土星 Saturn—12

Cassini has solved the mystery of how at least one of Saturn rails' formed, and this may help solve the bigger mystery of life beyond Earth, * may be the hottest ticket in town, but don't overlook the heavy weight container for the titan lovemoon wit

英语听力：自然百科 行星旅行：土星 Saturn—11

Heres the surprise entry into search for life, this little moon that youd expect to be pretty dead and dull, and coming out of the South Pole of it is a jet of water ice, all the things you need for life are there. Theres an energy source, theres a w

英语听力：自然百科 行星旅行：土星 Saturn—10

It was unraveling a puzzle and so the magnetometer team says lets go closer, as we go closer, we watched as the star went through and noticed the change in brightness, something is going on. We can see even from a distance, there seem to be this mate

英语听力：自然百科 行星旅行：土星 Saturn—9

We are interested in studying seasonal changes on Saturn, because of its extremes affected the rains. Already we know the sky was blue, when the northen hemisphere came out of the shadow and it's now turn sort of pinkish yellowish, hazy color, becaus

英语听力：自然百科 行星旅行：土星 Saturn—8

Saturns apparently peaceful appearance is due to a haze of high level ammonia in the upper atmosphere, by looking deep into Saturn in the infrared, using the planets own internal heat as a light source, Cassini has revealed the planets true nature. T

英语听力：自然百科 行星旅行：土星 Saturn—7

And the icy grains on the Saturnian beaches are washed by passing traffic. When a moon comes by, it creates a wake just like a motor boat creates a wake that goes behind it. And I kind of imagine the ring particles doing an intricate cosmic dance aro

英语听力：自然百科 行星旅行：土星 Saturn—6

Everyone is familiar with the rings of Saturn. But what would you highlight if it were you sending back the postcards? Every tour itinerary has one main attraction. With Saturn, you just can't miss the rings. As imaging team leader for Cassini, Carol

英语听力：自然百科 行星旅行：土星 Saturn—17

These are just bold first steps on a journey that's just begun. Even before the mission is over, Cassini has left a thirst for a return trip. Planetary explorer Jonathan Lunan and aeronautical pioneer Julia Nod think they know the perfect way to do i

英语听力：自然百科 行星旅行指南：木星 Jupiter—5

Halfway there, you bump into the Asteroid Belt. It is not like in the movies where you are dodging asteroids at every second. It is a The space is very big and the asteroids are a long distance apart, so you could travel through it quite safely. The