“Earth’s core is molten, so our planet’s magnetic field is induced by a WorldMags.net circulating electric current at the core” SPACE
Earth’s magnetic field Just where did our protective magnetosphere come from? Before we can understand how Earth’s magnetic field works, we need to first have a basic understanding of magnetism. Magnetic fields are formed when electric charges move through magnetic materials like iron. Any magnetised material is dipolar, which means it has a north and south pole, and the magnetic field lines run from north to south. The magnetic field lines at the north pole swing back round to the south pole, creating an external magnetic field outside the material that can influence other things that get too close. You’re probably familiar with a bar magnet, and in essence Earth’s magnetic field is very similar to that; imagine a giant bar magnet running through the core of Earth from pole to pole and you’ll get the picture. However, Earth’s core is molten, so our planet’s magnetic field is induced by a circulating electric current at the core. One of the outcomes of this is that, on rare occasions, Earth’s magnetic field can flip. This is believed to happen once every 200,000 years on average. Taking the ‘bar magnet’ through Earth analogy further, it just so happens that the south pole of Earth’s magnetism is at the geographic north pole, and the north pole is at the geographic south pole. When someone refers to ‘magnetic north’, they’re actually referring to the south pole of Earth. Earth’s magnetic field is also not perfectly aligned with the rotation of the planet, instead being tilted at an angle of 11 degrees. It’s also not stationary; the magnetic poles are constantly moving, and indeed the south magnetic pole (at geographic north) has drifted up to 1,100 kilometres (684 miles) across the Canadian Arctic over the past four centuries. Interestingly, though, despite the size of Earth, the magnetic field is weaker than a fridge magnet. However, that’s still enough to protect us from harmful radiation from the Sun and elsewhere in the galaxy, and helps our planet retain its atmosphere.
020 | How It Works
Core Earth’s liquid core creates an electric current that in turn forms a magnetic field around the planet.
Solar wind Incoming solar radiation is deflected by Earth’s magnetic field, protecting us from harm.
Weakest point The magnetic field is weakest at the equator where the field lines are most spread apart.
Strongest point The magnetic field is strongest near the poles where the field lines converge.
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