标签：地球观测卫星 相关文章
A male polar bear is searching for a mate. Willing females are few and far between. And the sea ice some of which he travels will soon melt and vanished. He's running out of time to find the mate in this frost frozen desert. Ten miles ahead, a single
自然百科2011年
I am standing at the North Pole, the very top of the earth. Up here, it's easy to see why the Polar Regions are so cold. The sun never rises high enough in the sky to warm my back. And those rays that do strike the surface are mostly reflected back f
自然百科2011年
French researchers are predicting doom for Planet Earth. They believe neighboring planets could stray out of orbit and collide with the Earth billions of years from now. The BBC's David Shukman explains their theory. A view of Earth from orbit and a
万花筒2009年
Few have witnessed this moment, for the male, his only tender encounter in an otherwise solitary life. But it doesn't last long. A rival suitor has also caught the female's scent. Courtship has to be put on hold. He must fight for his rights. He sees
自然百科2012年
It's time for the couple to go their separate ways. She will give birth to his cubs alone in nine months time. And he may never see her again. He returns to the frozen ocean, no doubt relieved to resume his solitary ways. And just in time, the ice be
自然百科2012年
For those who can get here in summer, these waters provide a feast of epic proportions. But the good times will be very short, a problem that faces all life in the Polar Regions. Journeying the south across the Arctic Ocean, the first land you/ reach
自然百科2012年
This, Jakobshavn Isbrae, is the fastest flowing glacier on our planet, moving as much as 14 meters a day. As it advances, it destroys everything in its path, even cutting its way through Greenland's great mountain ranges on its drive downwards toward
自然百科2012年
Radiation causes damage at the most fundamental level. It mutates the blueprint of life, DNA. Earth's magnetosphere is our crucial defense. It's so fundamental to our evolution and continued existence that the race is on to understand why it's changi
自然百科2011年
During its magnetic cycle, the Sun undergoes periodic changes in activity. Every 11 years, it enters solar maximum. This 11 years cycle of solar activity has peaks where theres lots of solar storms. And right now where the sun is taking a little napp
自然百科2011年
Six years later, they come to believe these light flashes are the results of high energy, heavy cosmic rays penetrating the spacecraft and the crew members' eyes. These/ protons or electrons, just very, very high energy, ripped / part of atoms, sprin
自然百科2011年
By analyzing thousands of lava samples, geophysicists discover/ that the Earth's magnetic field has reversed over 18,000 times in the last 20 million years. On either side of these reversals is a long period of dramatically reduced field strength. Du
自然百科2011年
If we could flip a switch and just turn off the Earth's magnetic field, it will take about 15,000 years to disappear, based on the rate of decay of the field that we've seen over the last 150 years. It's currently decaying at a rate that would see an
自然百科2011年
In polar regions where the magnetic field is / weakest, auroras glow in the sky. These dazzling displays of colored lights form when solar particles slam into gases in our atmosphere causing them to glow. The stronger the solar wind, the more dramati
自然百科2011年
Scientists believe that the South Atlantic Anomaly, is a sign of a global decline in the magnetic field. Evidence of this comes from a surprising source. Dr. Mimi Hill uses pottery to uncover the secrets of earth's magnetic past. Ancient pots tell us
自然百科2011年
Easily confused by this idea, there has a big thawed iron inner core, so that I think it's just the bar magnet, just permanent magnet frozen in nad, and that's where causes all the magnetic field. But it's too hot inside the Earth, that can't happen
自然百科2011年
The rule is what goes up must come down, but the trouble is nobody knows exactly where the six-ton NASA satellite will crash land. This white blob is the UARS probe as it spins out of control during its descent, the footage was taken by an astronomer
英伦广角
They were travelling on foot and their first sight of this mountains must have been daunting indeed. In front of them stretched one of the world's longest ranges, spanning two thousand miles from one side of the continent to the other. The winds uphi
自然百科2012年
Youve got these beautiful clear glass-like pillars and right next to it, its really delicate. Look at in them, filament is there. As the cave team explore deeper, each chamber reveals ice crystals more strange and spectacular than the last. No one on
自然百科2012年
End of the run. No! Ive got him coming out, I just didnt get him going back in. All right! Below the sea ice, the dive team is setting up an underwater studio. Using a rang of waterproof lights and time-lapse cameras, they hope to capture the growth
自然百科2012年