Tuesday, August 26, 2008

Cow Compass?

Moooooove over. Cows can sense the Earth's magnetic field and use it to orient themselves in a north-south direction while grazing and resting, according to a new study by German scientists.

In what might be oddest use of Google Earth I've encountered yet, zoologist Hynek Burda and his team zoomed in on more than 8,500 unsuspecting cows in 300 pastures all over the globe.

Analyzing the satellite data, the team found that entire herds of cows will face either magnetic north or south as they go about typical sedentary activities like eating and sleeping, irrespective of the direction of the sun and wind.

But what about deer? Turns out they too can sense the giant magnet. Burda and researchers traveled to 241 fields in the Czech Republic, where they observed deer grazing in a north-south direction. Their body imprints left from a night in the snow further indicate that deer are orientated north-south while they sleep.

The origin of geomagnetism still isn't completely understood, but scientists believe the Earth's magnetic field is produced much like a bar magnet, by the motion of electrical charges. Inside the Earth, a spinning liquid metal core of iron and nickel generates electrical currents.

Evidence for this lies in "magnetic fossils" or molten rocks that hardened in a way that leaves distinct traces of the geomagnetic field's direction at that time. These rock specimens have shown that the magnetic field has reversed at least 171 times during the past 71 million years.

The geomagnetic field is important; it shield the Earth from solar wind (streams of gases that jet out of the Sun). The magnetosphere is a portion of space surrounding the earth that acts as a deflector, directing the solar wind off course and away from the Earth.

The next step is for scientists to figure out why animals align themselves in a magnetic north-south direction, some believe the behavior may relate to an anti-predator mechanism.

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