Viewing a single comment thread. View all comments

FootballImpossible38 t1_j5o4yrl wrote

So if the core slows/stops/reverses course then shouldn’t the magnetic field lines of the earth also flip or change in accordance? And if so wouldn’t this transition allow solar wind particles to bombard us in the meantime?

10

wazoheat t1_j5oxpe7 wrote

The core is not stopping or reversing it's course. That would be impossible due to being a violation of conservation of momentum.

The study that has been making it's rounds in the media suggests that the core has slightly changed it's rotational velocity relative to the surface, so that it is now spinning slightly slower compared to the surface rather than slightly faster as has been previously noted. They also show evidence that this may be a cycle that reverses every few decades. This is unrelated to the magnetic dynamo of the earth and it's roughly 100,000-year cycles.

The media coverage on this study is probably the worst I have ever seen. It's a very simple concept to explain, but if you explain it correctly it's boring, so I have to imagine that the journalists involved are being wilfully mislead, writing willfully misleading articles, or some combination of both.

26

CrustalTrudger t1_j5p2vp7 wrote

It's really bad. Even the publisher is making pretty misleading comments about the paper, like this tweet from Nature that pretty much implies that the inner core is somehow not rotating at all or rotating in an opposite direction.

9

Cobra800089 t1_j5oh81s wrote

Yes, and yes. The magnetic field has flipped before, and during the transition the magnetic field is very weak.

However IIRC it takes on the order of hundred to thousands of years, so probably not something we'll have to worry about. Although the timeline in the article OP is referring to seems to state it's happening faster than we previously thought. (IIRC, In the 90's the core was spinning faster than the planet, by 2009 it was spinning slower)

12

FootballImpossible38 t1_j5ohryp wrote

thanks. i must have mis-read recent news articles that stated that the core had reversed its spin and was now spinning in the opposite direction. this implied to me that the field reversal must have already happened in short order and so we would have seen the effects of that weakening here on the surface.

5

dukesdj t1_j5omgh1 wrote

There is a difference between the inner and outer core. The inner core is approximately solid while the outer core is liquid and is the region that produces the geodynamo. The geomagnetic reversals are more related to the fluid motion in the outer core than the rotation (and/or differential rotation) of the inner core.

6

wazoheat t1_j5oxz86 wrote

I'm not going to blame you, the media coverage on this has been atrocious. Willfully misleading I'd say

5

FootballImpossible38 t1_j5pbhan wrote

one expects sensationalism out of the National Enquirer, but not from so many of the more (formerly) respected outlets that covered this story. everyone's out for click-bait it seems.

2

Clarknt67 t1_j5rf95h wrote

I don’t think the flipping of the magnetic fields poles is at all related to the direction of Earth’s core. I don’t believe the core can change direction or has been asserted to have ever changed direction. I am sure it can slow down and probably speed up, though.

3

Cobra800089 t1_j5rhuvv wrote

Thanks for the clarification. It looks like there is no consensus on why the magnetic poles flip.

1

Clarknt67 t1_j5s09as wrote

I agree. I don’t think the magnetic field is definitively understood. Oddly. Since it’s all around us.

1