Has Earth's magnetic field changed significantly over time?

Answer 1

Based upon the study of lava flows of basalt throughout the world, it has been proposed that the Earth's magnetic field reverses at intervals, ranging from tens of thousands to many millions of years, with an average interval of approximately 250,000 years. The last such event, called the Brunhes-Matuyama reversal, is theorized to have occurred some 780,000 years ago.

There is no clear theory as to how the geomagnetic reversals might have occurred. Some scientists have produced models for the core of the Earth wherein the magnetic field is only quasi-stable and the poles can spontaneously migrate from one orientation to the other over the course of a few hundred to a few thousand years. Other scientists propose that the geodynamo first turns itself off, either spontaneously or through some external action like a comet impact, and then restarts itself with the magnetic "North" pole pointing either North or South. External events are not likely to be routine causes of magnetic field reversals due to the lack of a correlation between the age of impact craters and the timing of reversals. Regardless of the cause, when magnetic "North" reappears in the opposite direction this is a reversal, whereas turning off and returning in the same direction is called a geomagnetic excursion.

Answer 2

The Earth has a magnetic field .However its not constant it may have changed in the past; perhaps there was less magnetic field than. That may have been one of the reasons for the greater longivity of Humans at that time.
At present there is less magnetic field than the past. This could be the reason why life hardly goes beyond one hundred years old.
Harmfull radiation is what shortens life in Humans.What is protecting us from that radiation is the VAn Allen belt around the Earth which deflect the harmull radiation in the solar wind.The Belt is none other than the shape of the Earth's Magnetic Field.

Answer 3

it will be disastrous for all living issues. that is speculated once back speculated that the Aurora Borealis would properly be considered far south if it really is the case image voltaic winds from the sunlight ought to doubtlessly disrupt many digital gadgets, birds would lose there sense of route and compasses would fail. The worst case problem is that if Earth did lose its shielding magnetic safeguard, the ambience would enhance and change into thinner, probable ensuing in altitude affliction close to sea element. now no longer filtered out, deadly cosmic rays would kill maximum if, no longer all, living creatures on the outdoors. merely those living in deep caves will be possibility-free. Einstein once wrote that between the biggest unsolved complications in physics dependent round Earth's magnetic field.

Answer 4

Yes, although I don't know to what extent.
The magnetic field is due to the molten iron core of the earth being spun round by the earth's rotation.
As the earth cooled, the iron also cooled and less of it was molten.
So it must have decreased I suppose ?

Answer 5

well not many people are sure but if it has then that is probably the reason for why the o-zone layer is depleting. every couple of hundred thousand years or so the earths magnetic field switches, before this happens the o-zone layer starts to deplete. this means that north will become south and vice versa