What are some ways that the earth acts like a magnet?

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    So what do we know about gravity? We know that it causes any two objects in the universe to be drawn to one another. We know that gravity assisted in forming the universe, that it keeps the moon in orbit around the Earth.
    You see gravity at work any time you drop a book, step on a scale or toss a ball up into the air. It's such a constant presence in our lives, we seldom marvel at the mystery of it -- but even with several well-received theories out there attempting to explain why a book falls to the ground (and at the same rate as a pebble or a couch, at that), they're still just theories. The mystery of gravity's pull is pretty much intact.

    The Earth is a giant magnet, with a north magnetic pole and south magnetic pole like the two ends of a bar magnet. And like a bar magnet, the Earth is surrounded by a magnetic field that interacts with electrically charged or magnetized matter, causing effects ranging from deflection of the solar wind to keeping a compass needle pointing north.

    Scientists believe that the Earth's magnetic field originates in the planet's outer core of liquid iron. The outer core surrounds the solid iron inner core and transfers heat from the inner core out to the mantle and crust by convection. The inner core is further roiled by the Earth's rotation. All this motion of an electrical conductor in a magnetic field creates electrical currents which in turn generate the magnetic field. This is called the "dynamo effect." The dynamo effect is not completely understood, but recent computer models have produced results very similar to observation.

    Because of the chaotic nature of the movement in the outer core, the Earth's magnetic field can fluctuate considerably in intensity and orientation. Geologists study the orientation of iron atoms in rocks of various ages to track the magnetic field through time and have found that it sometimes flips polarity, with the north magnetic pole moving to the south geographic pole, and the south magnetic pole moving up to the high northern latitudes. Computer modeling shows these flips are accompanied by a period of great complexity in the magnetic field, which fragments into two or three pairs of north and south poles at various places around the globe that then coalesce back into one dipole. Currently, the Earth's magnetic field is quite strong compared with past ages, although it has weakened about 10 percent in the last century or so.

    Read more: How Does the Earth Act Like a Magnet? |

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