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.

At least it is not as bad as with the Sun. The Sun's magnetic field reverses direction about every 11 years.

Here's another one. Does everyone know that...

The North American Plate is pulling away from the Eurasian Plate in the Atlantic ocean. At the boundary is the Mid-Atlantic Ridge. The rate is such that the Atlantic Ocean is widening is about 5–10 centimeters per year.

The opposite is happening in the Pacific Ocean where the Pacific Plate is descending under the Eurasian Plate. At the boundary is the Marianas Trench which is almost 11,000 meters deep.

Now, see-- I didn't realize that the sun's field flipped on the 11-year cycle, so now I've learned something. Thanks, Ed!

There are people that would argue otherwise!! Muppets!!!


lol, that would be funny!!

The results are kinda what I was expecting. I would definitely say the folk on this forums are a bit more with it than the average punter!

Now this is something I know. I spent alot of time monitoring the solar cycle (specifically to see when the aurora borealis would make an appearence in the NY skies for a change). The magnetic field on the sun usually flips on solar maximum when the number of sun spots is the greatest. Sunspots create magnetic fields of their own, which eventually weaken the suns field and cause the north pole to migrate to the south, and visa versa.

Unfortunately, I live in Charlotte NC, now, and generally you need a pretty hefty CME to get the aurora to show up all the way down here. Only one time has that happened (around solar max) that I can remember.

Don't feel too bad Ramses; the rumors I've been hearing say that the next time we hit solar max, it's going to be a really MAJOR maximum. As in history-making maximum. As in you just might see the AB even that far south.

How many people even know how to use a compass? Now everyone seems to rely on GPS. You would think that with GPS it would be harder to get lost. In a report I saw once the opposite was true. People were going out into the wilderness with no compass and were relying only on GPS to navigate. People were getting lost and required rescuing more often than before GPS.

Many years ago when I lived in northern Illinois I was watching a lunar eclipse in the southern skies. I just happened to turn around and look north. To my amazement the nothern sky had lot of aurora visible to the naked sky. The only thing that made it hard to see was the presence of the Moon. A few months later there was an article in Sky and Telescope magazine commmenting on the unexpected auroral display that night. They had a map plotting the parts of the US where reports of the aurora were sent in by readers. I was amazed that fartherest south they received a report was Wisconsin. If I had sent in a report I would have sent in a report that was farthest south.