Scientists say the planet’s inner core has ground to a halt, and looks set to start rotating in the opposite direction
There are some things in life that you can never take for granted – like District line trains, or the internet’s critical thinking skills – but there are others that seem pretty reliable, like the basic workings of the planet beneath our feet. Right? Well, apparently not. According to new research, Earth’s inner core appears to have stopped spinning in the last ten years. In even more surprising news, it could be about to reverse its course and start turning in the opposite direction.
This raises a lot of questions – mainly, what does it mean for us, the ones standing on Earth’s crust? Are we about to experience a planet-sized vibe shift? Is 2023 the year that Earth finally caves in on itself? Can NASA smash another spaceship into something to get the core going again? Will a reversal of the core’s rotation turn back time, and reverse the horrors of the last decade? Sadly, probably not.
As we all learned in primary school science lessons (and then forgot for several years, and then learned again courtesy of Google) the Earth is formed of four main layers: the crust, the mantle, and the outer and inner cores. Located about 5,000 kilometres below Earth’s surface, the inner core is a bit of a mystery, as we’ve never been able to extract a sample. According to current estimates, though, it’s a solid ball of metal that’s about the same size as Pluto, and as hot as the surface of the Sun.
We’ve also known for some time that the inner core is rotating at a different speed to the Earth itself, since it’s suspended in the outer core, a layer of fluid about 2,400 kilometres thick. Nevertheless, researchers from Peking University got a surprise when they analysed seismic waves for a recent study on the speed of the inner core’s rotation. The seismic activity (i.e. earthquakes that have coursed in similar directions through the inner core since the 1960s) has previously changed over time, with clear differences between 1980 and 1990. There’s very little difference in the data gathered since 2009, though, as if the core’s rotation has ground to a halt.
“We show surprising observations that indicate the inner core has nearly ceased its rotation in the recent decade and may be experiencing a turning-back,” reads the study, published in Nature Geoscience by Yi Yang, associate research scientist at Peking University, and chair professor Xiaodong Song.
Fortunately (depending on your current outlook on life on Earth) this wouldn’t necessarily be a cataclysmic event. Song and Yang suggest that the slowing – and potential reversal – of the inner core’s rotation could be caused by a minor imbalance in the electromagnetic and gravitational forces that hold the universe, and by extension planet Earth, together. They also note that a similar turning point was recorded in the early 1970s, and suggest that the new finding could be part of an ongoing seven-decade cycle.
That isn’t to say that we haven’t felt the effects of the inner core’s movements without knowing it. The researchers have tentatively suggested that it could be responsible for slight changes to the length of Earth’s days, or oscillations in sea levels and global temperatures. At the end of the day, though, they conclude that we’ll need to observe future changes, and construct models of the core’s rotation, to figure out if it does significantly affect life on Earth’s crust. In the meantime, the inner core remains a mystery.