Wednesday, February 24, 2010

Magnetic Reversals

Maddy here!

When my brother, Mica, and I ended up in Krybos last summer trying to outwit an interior world madman, concerns over disruptions in the earth's magnetic field came up. Mica wanted to know what dangers, if any, could occur from this field getting reversed. So, what did I do? I did what any self-respecting big sister would do. I lied to him. Well, I guess "lie" is kind of a strong word for it. I was really just pulling his chain by choosing what to say. Mica asked me if a magnetic reversal would affect us, and I told him no one knew the answer to that since humans had never been around during one.

Technically, it's all a matter of perspective. There are those who say that all creation and man only appeared roughly 6,000 years ago. Then there are those who point to the fossil record that dates Homo sapiens' appearance on the planet back about a half million years ago, and modern Homo sapiens to only 100,000+ years ago. But the fossil record also indicates that humans "in some form" have been around for about two million years, and a number of pole reversals have occurred during this time. And yet, life is still here.

I could've just told Mica that nothing would likely happen and left it at that, but I do thoroughly enjoy messing with him! All he'd have to do is pick up a book from time to time, and he might already have known the answer. It doesn't hurt Mica one bit to sweat about it anyway. If he gets curious enough, he can do some research.

Speaking of research, since school's been out a lot because of the snow I've been reading up on 2012 lore and the Mayan long count calendar bak'tuns. It's all pretty interesting stuff. I also read where a group of people actually thinks a magnetic pole reversal in 2012 will cause the end of life on earth. Others says a "pole shift" will be the culprit. When I say "pole shift," I mean when the earth wobbles on its axis. It's certainly happened before, and will likely happen again, but I don't think we'll croak over it. I'll delve into that shift in a separate blog post. For now, I would like to offer some thoughts on magnetic pole reversals.

Earth has a magnetic field that is generated by its rotating core. Actually, it's a dual core. There is a solid iron inner core and a liquid outer core. Anyway, it's when this magnetic field is disrupted that a magnetic pole reversal occurs. The north pole becomes the south pole, and vice versa. The last time it happened was about 780,000 years ago., and since humans (in some form) were on the planet, and humans are still here, that would lead me to believe it's a survivable event! The image at the right is a graphic representation of the field.

We know how frequently these reversals occur by studying the magnetic anomalies of the sea floor on either side of the mid-Atlantic ridge. The paleo-magnetic evidence is found in the mineral alignment in this iron rich rock. When the rock is laid down during sea floor spreading, the minerals orient according to the earth's magnetic field at that time. When the north pole is on top of the earth, the minerals align in one direction, and when the south pole is on top, the minerals align in the other direction. Pretty simple stuff there.

We also know from the rock that magnetic reversals occur at irregular intervals, but the typical period between reversals has been averaged at 250,000. Using that number, it could be said that we are overdue for one. But reversals take hundreds, even thousands of years to take place. So, we're not going to wake up one morning and discover that our compasses point south, although that would be pretty weird. It's a gradual process, and no single person will see one occur from its beginning to its end.

The paleo-magnetic record also indicates earth's magnetic field intensity during the time that the rock was laid down. This is important because, historically, it shows that reversals occur when the magnetic field is at its weakest. And currently, the global magnetic field is in decline. Snap! I forgot to mention that to Mica. He would absolutely freak out! And again, he could "grab a book, get an answer." However, in and of itself, this decline is really no big deal because the paleo-magnetic record also shows us that some fluctuations are always occurring. The field may weaken, but then it'll come right back.

So what's my take on this being an issue for mankind in 2012? NOT. I think the solar flares and sun spots will probably get us before then.

That's all for now.

(Here is a link with an excellent graphic of reversals dating back over 150 million years:

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