Science: Technoquest
Your support helps us to tell the story
From reproductive rights to climate change to Big Tech, The Independent is on the ground when the story is developing. Whether it's investigating the financials of Elon Musk's pro-Trump PAC or producing our latest documentary, 'The A Word', which shines a light on the American women fighting for reproductive rights, we know how important it is to parse out the facts from the messaging.
At such a critical moment in US history, we need reporters on the ground. Your donation allows us to keep sending journalists to speak to both sides of the story.
The Independent is trusted by Americans across the entire political spectrum. And unlike many other quality news outlets, we choose not to lock Americans out of our reporting and analysis with paywalls. We believe quality journalism should be available to everyone, paid for by those who can afford it.
Your support makes all the difference.Q: Why do the Earth's magnetic fields flip every million years or so?
The current understanding is that the Earth's magnetic fields are produced by a complex system of electric currents circulating in the molten part (not all of it is molten) of the Earth's iron core. The currents exist because the molten iron is a good electrical conductor and is undergoing convective stirring as it passes its heat upwards into the overlying solid mantle. The currents produce a magnetic field in a similar way to an electromagnet; but the whole thing is more complicated because the magnetic field interacts with the electric currents and keeps changing the convection pattern.
Inside the core the magnetic field is complicated but, fortunately, the net effect seen from the outside is less so, and the Earth's field we measure at the surface is rather like that from a bar magnet which is slowly wobbling. This is why the direction of magnetic north changes slowly with time.
It seems that the convection process sometimes gets into a pattern where the magnetic field seen from the outside becomes very small and then grows again but with the opposite polarity, ie reverses. This has been shown to occur in some mathematical models of the Earth's core and also in physical models (involving complicated systems of bar magnets and coils of wire in the laboratory). The only problem is that we are not sure whether these models are exactly like what happens inside the Earth's core, so we cannot predict just what to look for when a reversal is imminent. The bottom line is that we understand the process in general, but not yet in extreme detail.
Funky human body facts
If you placed all of your blood vessels end to end, they'd stretch for 97,000 kilometres (60,000 miles) - twice the Earth's circumference.
On average there are 100,000 hairs on the human head. Redheads have about 90,000, people with blond hair 140,000 and those with brown hair something in between.
It takes 17 muscles to smile; 43 muscles to frown.
Technoquest website: http:// www.sciencenet.org.uk
Join our commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies
Comments