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Video Description
What is weakening Earth-s invisible shield? Magnets have the power to attract and repel-sometimes on a massive scale. The Earth-s molten core-a violent mix of searing heat， crushing pressure， and a billion trillion tons of liquid iron-creates an invisible shield that surrounds the globe， guarding against a constant barrage of deadly radiation from space. But over the last few decades， the Earth-s magnetic field has weakened dramatically， intriguing scientists across the globe. The power generated 2000 miles beneath our feet protects us every day， but the loss of Earth-s magnetic field is a brewing storm that affects us all. While experts research and debate， persistent questions remain. Is a rare geomagnetic reversal the cause of earth-s inner turmoil? And if the magnetic field were to vanish altogether， would Earth become as lifeless as Mars? Travel from Hawaii-s molten lava flows to the mountains of Oregon and into the far reaches of outer space for a charged look at Earth-s magnetic history and potentially deadly future. Special DVD features include: materials and activities for educators; a link to the NOVA Web site; scene selections; closed captions; and described video for the visually impaired. On one DVD5 disc. Region coding: All regions. Audio: Dolby stereo. Screen format: Letterboxed.