Artist's rendering of the Earth's magnetosphere

Pole to Pole to Pole

When my family and friends heard the special Christmas edition of Conversations in Science, many of them asked the same question: had I been drinking too much eggnog? In listening to the episode myself, I must admit, I did sound a little crazy, but I'm not. The ideas that I mentioned in that episode really do have a scientific basis.

So in my defense, I decided to elaborate on the scientific principles mentioned in that Christmas edition for this month's episode of Conversations in Science.

Pole to Pole to Pole
(First aired on KLRNRadio, Monday, January 9, 2017)

By naming convention, the end of a magnet that points towards the Earth's North Pole is the North Pole of the magnet. However, when we examine the Earth's magnetic fields and how magnets behave, everything suggests that the Earth's North Pole is really a magnetic South Pole.

First, consider what happens when you try to push the North Poles of two bar magnets together. It takes a significant amount of brute force to achieve it, if it can be achieved at all. Like poles repel, whereas opposites attract. But this is not the only scientific reasoning.

Shows a diagram of magnetic field in a situation of repelling and attraction

Magnetic fields want to flow from North to South, hence, opposite poles will attract but like poles will repel.

The magnetic fields around a bar magnet have a directional flow that stems from the North to the South. It has only been within more recent history, since the invention of satellites, that we've been able to successfully measure the true directional flow of the Earth's magnetic field; it flows from South toward the North and the magnetic polar axis does not align perfectly with the geographical poles.

Representation of Earth's Magnetic Field

Schematic illustration of the invisible magnetic field lines generated by the Earth, represented as a dipole magnet field. In actuality, our magnetic shield is squeezed in closer to Earth on the Sun-facing side and extremely elongated on the night-side due to the solar wind. (Image Credit: NASA / Peter Reid)

The geographical poles of the planet are actually defined by the stars. If you were to stand at one of the poles and look straight up, the stars would be moving around in circles above your head. This celestial pole extends from the geographical pole and defines the Earth's axis of rotation.

Anyone who has ever learnt how to properly read a compass for navigation will know that the geographical North Pole is offset from the magnetic pole, and that offset changes with time. Topographical maps are printed with a variance for the magnetic pole and a calculation for the added shifts. Anyone wanting to navigate through the forest needs to include these shifts, or they'll find themselves going in the wrong direction.

These changes can be measured through scientific methods and all evidence is pointing to an increasing unstable flux and a near-future magnetic field flip.

Geological surveys have suggested that the Earth's magnetic field goes through periodic shifts, flipping poles roughly every 200,000 to 300,000 years (although its been roughly twice that long since the last flip), with flips taking in the order of 1000 years to complete. Satellite measurements of the Earth's magnetic fields suggest that we have already started the transition period. Exactly how long it will take before the full flip occurs... Scientists can't answer that question without more data, however, the team at Pittsburgh Supercomputing Center and the Los Alamos National Laboratory have spent years working on computer models to help answer that question, among many others.

Expected structure of magnetic field during a shift

Supercomputer models of Earth's magnetic field. On the left is a normal dipolar magnetic field, typical of the long years between polarity reversals. On the right is the sort of complicated magnetic field Earth has during the upheaval of a reversal. (Source: NASA)

When the flip finally occurs, it will NOT be the end of the world. Yes, our planet will become more susceptible to solar radiation, and yes, we will likely experience climate changes, but we WILL survive. Many species currently on Earth were around during the last flip, including humans (more accurately, homo erectus).

However, our current electrical world might suffer (disruptions to Internet... the horror...), but I'll stress it again — we WILL survive.

Sorry to all the doomsday conspiracy theorist, but on this matter, you don't have my support.

Feature Image: An artist’s rendering (not to scale) of a cross-section of the magnetosphere, with the solar wind on the left in yellow and magnetic field lines emanating from the Earth in blue. (Credits: Emmanuel Masongsong/UCLA EPSS/NASA)

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© Copyright, Judy L Mohr 2017

Posted in ConvoScience Podcasts (Archive), Science and tagged , , .

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