January 8 marks Earth’s Rotation Day, commemorating the date French physicist Léon Foucault demonstrated the effect of Earth’s rotation using Foucault pendulum. But have you ever wondered what would happen if the Earth suddenly stopped spinning?

Earth rotates around its own axis roughly once every 24 hours. This spin causes day and night across the planet and helps keep the lowest part of our atmosphere, known as the troposphere, in a state that can support life on Earth.

If Earth’s rotation was to stop suddenly, a few things would happen, and they wouldn’t be pleasant.

Image: A Foucault pandulum at the Panthéon in Paris, France. This device is used to demonstrate Earth's rotation. Source: Rémih, CC BY-SA 3.0 via Wikimedia Commons

One of the first things that would occur if Earth stopped spinning would be the atmosphere and oceans suddenly surging towards the east. This would cause a sudden onset of cataclysmic wind that would dislodge everything not fixed strongly to the planet’s surface.

The fastest winds would occur near Earth’s equator, and they would become weaker as you moved towards the poles. Earth’s surface is moving at roughly 1,670 km/h near the equator while the Earth is rotating. If the planet suddenly stopped spinning, the air would suddenly move at about 1,670 km/h relative to the ground.

The strongest wind gust humans have every directly measured on Earth’s surface was 407 km/h at Barrow Island in Western Australia. The wind created by Earth’s rotation suddenly stopping would be more than six times stronger than this.

There aren’t many things on Earth’s surface that could withstand wind this strong. People, animals, trees, buildings, rocks, lakes, oceans and chunks of earth would be flung towards the east at a ferocious pace.

Video: Earth's rotation on April 17, 2019 captured by satellite. Source: NASA

Earth’s crust would also shift east when the planet stopped spinning, causing earthquakes, volcanoes and tsunamis on a planetary scale.

Once this turbulent aftermath of Earth losing its rotation calms down, one side of the planet would be left facing the sun and the other would be in darkness. Assuming Earth continued to orbit the sun, there would only be one day and night per year for every non-polar location on the planet, with each day and night lasting for about half the year (roughly 182.5 current Earth days).

Earth’s atmosphere would also start behaving very differently if the planet wasn’t rotating around its own axis. In the absence of the Coriolis force, air would travel more directly towards the north and south without being turned towards the east or west. This would create massive temperature contrasts between the light and dark sides of Earth, making parts of the planet experience temperatures that are unsustainable for life as we know it.

Earth’s ocean would also be left in a very different state. The loss of centrifugal force would cause oceans to slosh towards the poles and recede near the equator, possibly creating separate large oceans in each hemisphere.

All things considered, we should be grateful for the Earth’s rotation, which was made popular by Léon Foucault back in 1851. Happy Earth’s Rotation Day!