What would happen if our planet stopped spinning entirely?
Dr Karl Kruszelnicki
Dr Karl Kruszelnicki
Dr Karl is a prolific broadcaster, author and Julius Sumner Miller fellow in the School of Physics at the University of Sydney. His latest book, Vital Science is published by Pan MacMillan. Follow him on Twitter at @DoctorKarl
THE ROTATION OF the Earth is gradually slowing down. Back in the time of the dinosaurs, the day was 23 hours long. But what would happen if our planet stopped spinning entirely?
According to geographers, the oceans would retreat from the Equator, leaving it entirely above ocean level. You could walk all the way around the Earth at the Equator on dry land!
Over several billion years, the spinning of the Earth has made the planet a bit fatter around the middle. Today, the Earth’s diameter measured through the Equator is about 21.4km more than the diameter measured through the Poles.
This bulge in the ‘solid’ Earth took billions of years to slowly develop. This is because the solid matter moved only very slowly in response to the outward force caused by the spin of the planet.
But the liquid water in the oceans is far more mobile and responsive to forces. At the Equator, thanks to the spinning Earth, the water has been pushed up some 8km higher – as compared with the situation of the Earth having no spin. But today on the entire Equator the deepest part of the oceans is only about 5.75km.
So, if you take away the spin then you take away all water at the Equator. You could travel around the Earth on the Equator and stay entirely on dry land – ignoring the freezing cold on the night side, and the searing heat on the day side. There would be two totally disconnected polar oceans on each side of the new Equatorial megacontinent.
In the north, Canada would be entirely under water. And, roughly following the line of the border of current-day USA and Canada, all of Greenland, as well as the northern plains of Siberia, Asia and Europe would be under water. But Spain would mostly stay above water.
On the other side of the Equator, the new Southern Ocean would be much bigger. It would start roughly on a line running through current-day Canberra. Africa would be joined to Madagascar, while Australia would be joined to New Guinea and Indonesia.
The bright side is that over billions of years, the Earth would slowly recover its perfect spherical shape.