Earth's magnetic field


(Scott koshland) #1

Just curious, did you know that the Earth’s magnetic field has weakened about 10-15% over the last 100 years and appears to be still decreasing and the poles are moving their position?


(Matthew Pevarnik) #2

Are you asking everyone in general or someone specifically?

For the first part, are you hinting at geomagnetic reversals, of which we have measurements of 180+ over the past 80 million years? Your information is repeated in the Wikipedia article on the Earth’s Magnetic Field and contains some more historical information beyond the past 150 years.

For the second one, do you mean that the Earth is tilting according to Milankovitch Cycles?

Or maybe everything just looked like this:


#3

Wikipedia has a nice article on Paleomagnetism.

Whenever this topic comes up I remember a book I read back in 1973, Debate about the Earth by Takeuchi. It introduced me to the idea of continental drift. The pattern of magnetic reversals on the Atlantic sea floor was a powerful example of what we now call plate tectonics. I have yet to see any argument from a YEC that could explain these. And it also throws the magnetic field is weakening argument right out the window.


(Scott koshland) #4

Its just a general question. You don’t hear much about this. I think it s not well understood. A change in the earth’s magnetic field is not innocuous as the field blocks the suns CME and also cosmic radiation. Also if the poles start to flip, the process is not well understood and may have significant climate consequences and even geologic effects such as more volcanic activity and earthquakes.

I think its just strange you don’t hear about this? I guess it’s not man made effect…


(Matthew Pevarnik) #5

Who doesn’t really talk about it? You mean in political climate change debates? The Earth’s magnetic field obviously isn’t man made and it could have been a factor in previous mass extinctions. I can’t seem to pinpoint what you’re getting at or what your real question is…

On the other hand, humans actually have made a protective barrier around Earth- https://www.nasa.gov/feature/goddard/2017/nasas-van-allen-probes-spot-man-made-barrier-shrouding-earth


(George Brooks) #6

Like off-balance objects set into a spin in orbiting space craft (I’ve already posted a video of such an off-balance spin), the spinning metal core of the Earth flips now and then.

It is dramatic, but because it is a spheroid, not a spinning tennis racket, when it’s rotation flips, the repercussions are not usually catastrophic.

Since we know that the poles have flipped more than once in the recorded history that rock formations give us … and that life frequently carried on, it doesn’t appear to have much relevance.

However, it may well be that such a flip will cost us the use of those satellites that are not positioned (long term or short term) well within the body of the Earth’s magnetic field. And so I say: “We live in exciting times.”


#7

It happens frequently, in geologic time at least. The flips don’t seem to align with known mass extinction events. Why would there be a linkage with volcanic activity or earthquakes? They take place in the very thin crust and the magnetic field is generated in the core.


(Scott koshland) #8

Hi Bill, I just think it’s interesting. I don’t think that this flip necessarily that this leads to extinctions but may be very disruptive to our civilization. The magnetic field may reduce to a very low level during the flipping. That would reduce our protection from CME and cosmic radiation. That might effect our electric infrastructure. That might also h ave significant effects on climate. Also the flipping might have effects on volcanic activity and earthquakes. Just strange that you just are not hearing much discussion about this. This is not that irrelevant.


#9

From NASA
But, while Earth’s magnetic field can indeed weaken and strengthen over time, there is no indication that it has ever disappeared completely. A weaker field would certainly lead to a small increase in solar radiation on Earth – as well as a beautiful display of aurora at lower latitudes - but nothing deadly.


(Steve Schaffner) #10

The magnetic field doesn’t really protect the Earth from radiation – the atmosphere does that. The magnetic field is argued to protect the atmosphere from long-term erosion by the solar wind, but that seems to be controversial.


(George Brooks) #11

@glipsnort

Since, by definition, there is no atmosphere in orbit, are you saying that the Earth’s magnetosphere provides no additional protection to our satellites?


(Steve Schaffner) #12

No, I wasn’t talking about satellites. I was talking about things down here on the surface. We have a nice think radiation shield to protect us. Satellites don’t,


(George Brooks) #13

Well, this isn’t what I meant.

You provided a blanket statement that the magnetosphere is not what protects humans, it is the atmosphere.

If that were true, then this would mean the magnetosphere offers no protection to satellites.

Perhaps what you meant to say is that the lion’s share of protection comes from the atmosphere, and a little bit comes from the magnetosphere.

Clarify at your leisure. Thanks!


(Steve Schaffner) #14

I made a blanket statement about the Earth, by which I meant the planet lying under the atmosphere and anything living on it. I have never made any comment about anything above the atmosphere, mostly because I have no idea what the effect would be.

That is an accurate statement. I made a back of the envelope calculation many years ago (when I had access to appropriate envelopes) and concluded that there would be a modest increase in cosmic radiation at ground level. Googling today, I saw an unreferenced estimate of an increase of a factor of two in cosmic background radiation; if correct, that would mean an increase in total background radiation of something like 30%, which is not nothing but which is considerably smaller than the variation in background with location.


(Scott koshland) #15

Well I think it would be pretty cool to have the aurorea down in San Diego! Though this probably will not occur in my lifetime. A 30% increase in cosmic radiation (I have heard up to 200%) but 30% increase could still have significant impact on human infrastructure and planet climate. (astronauts can see cosmic radiation when they close their eyes) Also some of the models suggest that there could be huge areas of magnetic anomalies and even 4-8 poles that could again be disruptive. It is all very interesting this amazing world that our Lord has created. The Suns alternating magnetic field, solar radiation and solar cycles, earths complex atmospheric layers, a dynamic ocean, and dynamic magnetic core all combine to create an amazing and complex planet. I just think it’s all very interesting.


(Steve Schaffner) #16

I went with a 100% increase in cosmic radiation, which is roughly a 30% increase in total background radiation. (Most background radiation has terrestrial sources.)


(George Brooks) #17

Yep, this is consistent with some of the articles I was scanning…


(Scott koshland) #18

Got it. Just the same I expect that such an increase in cosmic radiation hitting the earths atmosphere could have substantial climate effects. And if the poles move toward the equator during the shift again that might concentrate the solar particles that normally hit the poles toward the equator that also may have climate consequences. There also could be effects on the ozone layer. I just think it’s odd that people are not talking much about this much in the media?


#19

From what I have heard and seen on TV documentaries (not exactly the best source), astronauts experience much higher levels of radiation due to high velocity particles (i.e. cosmic radiation), even at very low orbits. They even report seeing flashes from cosmic radiation striking their retinas.

As you or someone else stated earlier, the primary role that the Earth’s magnetic field plays in preserving life on Earth is protecting the atmosphere from being stripped away by solar winds. It is thought that the lack of a thick atmosphere on Mars is mainly due to a lack of a magnetic field.


(Matthew Pevarnik) #20

To affirm this there was a NASA astrophysicist who came by and gave a presentation on the dangers even with commercial airlines. It turns out that one of the most dangerous jobs that a pregnant woman can have is as a flight attendant.