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This is Scientific American's 60-Second Science, I am Cynthia Graber.This'll just take a minute. On earth, snow crystals as we all know, form from frozen water. But scientists believe there're also flakes that fall on Mercury, and they're made of iro
Scientific American(六)月
Scientists Work to Understand Earth's Magnetic Field 科学家们努力了解地球磁场 Most of us rarely think about the earth's magnetic field. We might know that it helps guide birds as they travel and keeps our compasses pointing north. But, th
2015年VOA慢速英语(八)月
The loss of the magnetic field has a catastrophic impact on the planet's evolution. Mars becomes the red planet we see today. If earths magnetic protection continues to fade, would it suffer the same fate? If it vanishes completely, the planet might
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
As the vast sphere reaches / maximum speed, something incredible happens. Huge lines of magnetism arc in and out of the model core. Well, we can't see the magnetic field coming out of the experiment, we can measure them, we can put many different mag
自然百科2011年
Larry Newitt from the Geological Survey of Canada charts the movement of the magnetic North Pole as it wanders the icy reaches of northern Canada. To determine where the magnetic pole / is, we can't rely on one single observation. What I try to do is
自然百科2011年