[原创]借块宝地练听力(每天一更新)

cvvt1986

Santa in Danger: Polar Meltdown

http://podcast.sciam.com/earth/sa_e_podcast_081211.mp3

cvvt1986

The North Pole is melting, and there's very little Santa can do about it. No matter how green his elves are.

It's worse for the Inuit people, polar bears, walruses, and a host of less charismatic residents of the far north. Inuit leaders repeatedly deliver warnings about dwindling caribou herds, ground collapsing from beneath villages and ice too thin to hunt on. This disappearing ice is the very reason polar bears are now listed as an endangered species.

Thin ice also allowed the first commercial ship, the MV Camilla Desgagnes to traverse the fabled Northwest Passage between the Atlantic and Pacific Oceans in September, delivering cargo to Inuit villages. It is a feat, long sought after (and died over) by European Arctic explorers—but it's not good news for Arctic residents.

The South Pole isn't faring much better. The Antarctic Peninsula is among the fastest warming locations in the world and, according to the European Space Agency, the enormous Wilkins Ice Shelf is in imminent danger of collapse, much like the Larsen ice shelf fragmented a few years back. That's bad news for global sea levels as well as would-be ice dwellers.

In future, Santa's reindeers may need water wings.

—David Biello

[此贴子已经被作者于2009-1-5 8:17:05编辑过]

cvvt1986

以下是引用Growingwqy在2009-1-4 19:14:00的发言：
好慢啊  几乎听不了, 缓冲缓冲...

可以选择下载听呀

cvvt1986

Milky Way Now in Larger Size!

http://podcast.sciam.com/daily/sa_d_podcast_090105.mp3

cvvt1986

We residents of the Milky Way should have a little extra skip in our step today. Turns out our home galaxy is much bigger and moving a lot faster than we previously thought. That’s what researchers from the Harvard–Smithsonian Center for Astrophysics reported January 5th at the meeting of the American Astronomical Society.

Older studies of our galaxy’s structure and motion used indirect measurements. But we can now use radio telescopes to directly observe certain features of the galaxy when we’re in very different places in our orbit around the sun. And using traditional surveying methods, such as triangulation, researchers came up with the new figures.

First, we’re moving about 600,000 miles per hour in our galactic orbit, a lot zippier than the old estimate of 500,000. And the Milky Way’s total mass is about half again as much as we used to think. Which means we’re about as massive as the nearby Andromeda Galaxy. The Milky Way’s bigger mass does mean a greater chance of a gravity-driven collision with Andromeda. But if that clash occurs, at least now we’re in the same weight-class.

—Steve Mirsky 

cvvt1986

Dead Stars Tell of Rocky Planets

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http://podcast.sciam.com/daily/sa_d_podcast_090106.mp3

今天去办中信的信用卡,对其要求本人出具30W虚假工资证明做法提出强烈抗议,气得我今天差点一天没听听力

[此贴子已经被作者于2009-1-7 21:20:27编辑过]

cvvt1986

If we want to learn more about our planet and other planets in the universe, we can get some help from stars that are long dead and gone. That’s what U.C.L.A.’s Michael Jura said at the American Astronomical Society meeting January 5th. His team used observations from NASA’s Spitzer Space Telescope to investigate dead white dwarf stars.

Dust and debris swirl around young stars. The pieces clump together to form asteroids and bigger planets. When a star like our sun finally dies, it blows itself up, bright red. Then it shrinks down into a skeleton of its former self—a white dwarf. The gravitational pull of these white dwarfs can attract nearby asteroids that then get pulverized.

Eight different white dwarf systems were examined. In the surrounding asteroid dust, there was a mineral similar to olivine, which is common here on Earth. And there wasn’t much carbon, also similar to the make-up of asteroids and rocky planets in our own solar system. The results suggest that the same materials that make up Earth and our solar system's other rocky bodies could be common in the universe. As could be rocky planets themselves. An insight for which we can thank dead stars.

—Cynthia Graber 

cvvt1986

Mars Is Alive! (Geologically, Biologically or Both)

cvvt1986

There’s definitely methane on Mars—and there are seasonal variations of how much is being released into the thin Martian atmosphere. Which means that Mars is still active geologically. Or that deep underground, something is or was alive. Or both. NASA and university scientists report the finding in the January 16th issue of the journal Science.

Researchers studying the Martian atmosphere discovered and measured methane levels over the last few years, using telescopes with infrared spectrometers. These instruments identify chemical compounds by analyzing their unique light absorption properties.

They found that Mars methane is being released as concentrated plumes at specific latitudes. Such plumes could come from various kinds of geological events. Underground bacterial communities could also be producing the methane. Or now-extinct living systems could have produced the methane long ago, with it only now being released through pores or fissures created by seasonal temperature variations.

On earth, 90 percent of the methane in the atmosphere comes from the biochemical activity of life. The rest is produced by geochemical processes. The Mars methane’s specific isotopic makeup could reveal whether its origins are biochemical or geological.

—Cynthia Graber

viviyh

大赞！！！！我也去听了～～