Monday, August 20, 2007
It is a well known fact that the earth's magnetic field protects us from Sun's solar flares and harmful radiations. It also gives us our North Pole and South Pole. So, if anything happens to this magnetic field, it would be quite catastrophic, right? Not quite. Pratik, my brother-in-law, said last weekend that the earth's polarity is changing. I google'd about this and found this lesser known amazing fact about the earth and its magnetic field.
Our geomagnetic field has existed for about 3 Billion years. The dipole polarity of this magnetic field has switched many times in the history since then. There is no rhythm or set pattern. The interval between the switch is not constant, but observed mean time between polarity switch has been roughly 200,000 - 300,000 years. The individual reversal events take about few thousand years. The last reversal took place about 750,000 years ago. So, does this mean that such a reversal of polarity is due sometime soon? Nobody knows because there is no set pattern that we know of.
At any time, the magnetic field is either getting stronger or weaker. According to Gary Glatzmaier, University of California professor, the magnetic field has been 10% weaker compared to the 19th century. Even then, the current dipole moment, the measure of intensity of the magnetic field, is 8.0 x 1022 amps x m2, twice that of million-year average intensity of 4.0 x 1022 amps x m2.
The poles are not constant either. Every few years, scientists travel to the frigid north pole to find the exact location of the magnetic north pole. Our north pole has traveled 100s of miles since the first time it was discovered by James Ross in 1831.
So, this means we are probably in the process of switching our polarity. During this time of transition, the strength of the magnetic field could wane, but it will never disappear. Many mini poles could pop up in various odd locations. The north pole could show up on top of Tahiti. It sure will be weird but it would be cool to be able to see northern lights in your shorts.
For further reading, read this article on NASA's website. It also has lots of great relavant links at the bottom of the page.
Image from: http://tonytalkstech.com