Earth ’s magnetic line of business is ourgreat guardian , shielding us from dangerous incoming solar radiation that would otherwise make life-time on Earth almost impossible . However , the strength of the field has exchange through geological clock time , with the poles of the planet ’s magnet switching dramatically at somewhat random intervals – roughly between200,000 and 5 million yr . Although thefield strength has been droppingfor the past two century , a new study , published in theProceedings of the National Academy of Sciences , suggest it is not in danger of flip any time soon .
Our satellite ’s magnetic field appear to be quite disorderly : It undergo not only reversals , but also sashay wherein the rod “ wander , ” changing their co-ordinate on the surface of the planet quickly with esteem to geologic time , before suddenly switch back to “ normal . ” Although themost recent reversaloccurred 780,000 years ago , the polestemporarily flipped during an excursionin the middle of the last ice age 41,000 years ago .
Today , we can accurately trace the changes in the orientation course and the strength of the Earth ’s magnetised field of honor in real fourth dimension , but predicting when it will dead flip again is no easy task . The current rate of its degradation has led some scientist to think that it will bottom out in 2,000 years or so , leaving the planet dangerously unprotected against our Sun ’s radiation . Whenever the magnetic field has attain a low-water mark in the geological past tense , it tends to flip over soon afterwards .
This new study , led by the Massachusetts Institute of Technology ( MIT ) , looked at the strength of the Earth ’s magnetic field over the last 5 million years by examining volcanic rocks . These ancient lava flow provide anancient criminal record of the satellite ’s field strength , locked in as they cooled below a particular temperature called theCurie point .
Image credit : When is the next big reversal due ? Triff / Shutterstock
They found that the modal sphere intensity level , as tape in Galápagos Archipelago lava menstruate , was close to 21.6 microteslas , represent the equatorial average . At the Antarctic , the average field strength was antecedently set up to be 33.4 microteslas , representing the pivotal norm . The forward-looking - Clarence Day airfield strength of the major planet , despite its late diminishing , isroughly twice as powerfulin both locations . So although the sphere long suit is still lessen , it is n’t minify to a " dangerous low-pitched " that will cause the poles to flip .
By this standard , it does n’t appear that we are due for a volte-face any time soon . However , as principal author Huapei Wang indicated in astatement , the behaviour of the Earth ’s magnetic field is incredibly irregular : “ Sometimes you wo n’t have a flip for about 40 million years ; other clock time there will be 10 flip in 1 million years . On average , the continuance between two somerset is a few hundred thousand years . The last flip was around 780,000 eld ago , so we are actually overdue for a flip . ”
As it turns out , this study is the first to appraise the Earth ’s ancient magnetic battleground strength from the equator : This supply a magnetic “ snapshot ” that premature studies have missed , according to Wang . In summation to this , Wang and his colleagues indicate that it was easy to incorrectly valuate magnetized field strengths from volcanic rock candy . So it could be that the assumption that the Earth ’s charismatic field is omit to a life-threatening low , asmany study purport , is wrong .
As for the when the next reverse is due ? The random nature of the Earth ’s internal dynamo signify that , grant to the study , no one can be sure .
