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  1. Earth

    Dead Serious

    Little progress has been made this decade in reducing the size of the Gulf of Mexico's dead zone, a massive area of oxygen-depleted water caused by agricultural and urban runoff.

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  2. 19910

    I believe that the term declination was used in error in this article. On any nautical navigation chart the difference between magnetic and true north is called “variation.” Declination has always been the angle from the horizon to a point higher into the sky. Bob NickelsonKing and Queen Court House, Va. While navigators use the […]

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  3. Earth

    North by Northwest

    The Earth's magnetic poles wander around quite a bit, a phenomenon that occasionally confounded ancient explorers but is proving useful for today's archaeologists.