英语听力：自然百科 穿越银河系的旅行 Through Milky Way—7

This is a picture of the Orion Nebula in visible light. We can see all of the gas here located in front of what we know are stars in the background, and we want to be able to look inside this nebula/ and see the stars. In infrared light in this image

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—6

Look closer and there is something strange about this gas and dust. There're patches where it appears to glow. These bright glowing clouds are called nebulae. And along with the Orion Nebula, our Milky Way has some spectacular examples, the Eagle Neb

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—5

We are taking a ride through the Milky Way. First, we are traveling to a place where stars are born. Even at the speed of light, 196,000 miles a second, the journey lasts for 1,500 years. We've arrived at the vast glowing cloud of gas and dust, the g

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—4

By comparing the detailed images, Hubble has taken another spiral galaxy. With the best images of our own taken from the ground, and by using satellites to measure the distance and density of stars in different directions, astronomers have been able

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—3

Now, of course, I can't show you a picture of the galaxy on our screen. We can't fly above the galaxy and take a picture of it, and show you. We're stuck in the disc of the galaxy, but we can still image it from the ground, in fact, this image is a p

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—2

It's really a wonderful time to be an astronomer, especially in studies of Milk Way. Were undergoing something for revolution. In fact, we can take you places. They're really quite remarkable. We are about to embark on an amazing journey. We'll take

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—1

We live amongst 200 billion stars, in the Milky Way galaxy, a vast cosmic city. The earth is located in a quiet neighborhood, in a safe neck of the woods. But what if we could take our planets on a journey through the galaxy? What wonders would be se

英语听力：自然百科 地球力场 Earth's Force Field—19

As the reversal approaches, the decay of our magnetic field will continue and cosmic radiation will get increasingly close to the Earth's surface. As the reversal approaches, the decay of our magnetic field will continue and cosmic radiation will get

英语听力：自然百科 地球力场 Earth's Force Field—18

Earth's magnetic field has reversed thousands of times since its formation 4.5 billion years ago. And scientists now believe that the next reversal is imminent. The race is on to predicting exactly when it will occur. In 2010, the European Space Agen

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—9

Like nebulae which spawn stars, it is made of gas and dust. But that's where most similarities end. For Alex Filippenko, it represents an intriguing industrial zone within our galaxy where the elements from which our world is made or manufactured. Wh

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—20

They were once thought to mark the outer limits, but today astronomers believe the Milky Way galaxy is much bigger than what we can see. To understand why, we will travel to the stars of the outer galactic disc. Far from our usual place in space, we

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—19

One of the puzzles about our galaxy is that we know that it's had stars forming continuously for about the last ten billion years. But at the rate/ it's eating up its gas now, it's forming new stars, it should burn out that gas soon, should run out o

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—18

Measuring the brightnesses and colors of the stars in the globular cluster, we can figure out how old they are. Here is the remarkable thing: they are very old. Globular clusters, at least the stars in the globular clusters, in many cases, are almost

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—17

We are traveling upwards away from our solar system, out of the spiral arms of the Milky Way. In front of us, lie vast clusters of stars, satellite groups that orbit the heart of our galaxy. These are globular clusters, over 150 have been discovered.

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—16

The glowing region is the accretion disc, star debris falling inward, would turn round in the maelstrom heated by frictions to such high temperatures that it glows white hot. So at the center of our galaxy, we do have a black hole. We now know that t

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—15

Each tag is whipping around the center of the galaxy, the particular, the most striking thing you will notice is the motion of SO2.So SO2 goes on an incredible roller-coaster ride. It comes whipping around and then back out. Something with tremendous

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—14

Its a stunning location, but its also mysterious. These stars are not just close together. They are on the move at enormous speeds. Going to the heart of a galaxy might not be the similar to going to an amusement park. The rides are some similar to h

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—22

All of the galaxies, all of the stars, and gas and dust and planets, and everything else that we can see with our greatest telescopes represent about half of one percent of whats actually/out there. The rest is invisible. It is mostly some mysterious

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—21

Imagine the disc of our galaxy, if you just took a disc of stars and put it there, gravity would tend to make this disc collapse/ into itself and it would immediately just fall together. That is not what we see with the galaxy. Whats actually going o

英语听力：自然百科 穿越银河系的旅行 Through Milky Way—23

But dark matter does more than simply holds galaxy like ours together. Astronomers think it binds the Milky Way into an extraordinary structure along with billions of other galaxies. To explore it, we'll take a journey to the very edge of the univers