Did you know the Earth's Magnetic Field Reversed?

I study how the magnetic field behaves with time, well I'm tying to find better ways of getting the data we need to understand it.

One of my colleagues is writing a book on the history of the study of magnetism aimed at the general reader. They commented that most people don't realise that the polarity of the geomagnetic field has frequently changed direction during the history of the Earth.

I was a little surprised as, since I have studied it, the notion of reversals is so intuitive me.

So I'm curious, how many folk out there knew the field reversed direction??

ironically (like much else) we're overdue for a flip.

just imagine what it could do to electrical equipment .

That's on on average over the relatively recent past. There has been a period with no apparent reversals that lasted for ~37 Million years (Cretaceous Normal Superchron)
And unfortunately there is no predictability to the reversal pattern (yet)



I've often wondered about that. If it were instantaneous then we might see an effect, but a reversal takes a few thousand years to complete. And during this time the strength of the field drops to ~20% of its normal strength.
The field is relatively weak anyway so hard drives and the like will probably not be affected. They get shipped around the world and the field varies quite a lot globally and there is no significant detrimental effect.

Satellites would be worst affected though, they would be much more exposed to cosmic radiation
[sigh] goodbye sky sports [/sigh]

Yes, I knew that... :-)

Ya i knew it flips from time to time as well.... Always wondered how many people would get lost when their compases point south as a result.

Most of the time its not even north or south anywho, since it slowly switches.

Earth has a magnetic field? ...

Do not confuse me with your technical jargon and scientific mumbo-jumbo.


It is even more amusing if you imagine the above being said by Gilbert Gottfried

you guys are lying you didnt know this.
i certainly didnt

I dont claim to know much about magnetic fields. But from what Ive read, two fields interacting cause an eventual equalisation, then it collapses and "flips." At which point, electrical equipment will...........





























be just fine.