What if Earth suddenly stopped spinning?
The ground stops. Everything on it doesn't.
The Day the Ground Stood Still
Pune, 2094. Tara was forty metres underground when the planet stopped turning.
1. The Stop
Tara was on the 7:40 metro under Shivajinagar when the world stopped. There was no warning siren. Just a deep groan in the rock, and the whole train lurched sideways as if a giant had kicked it.
Up on the surface, everything that wasn't bolted to bedrock kept doing what it had always done: moving east at about 1,580 kilometres an hour. Buses, trees, temples, the air itself. Only the planet had stopped. Down in the tunnels, wrapped in solid basalt, the passengers moved with the rock, and that is the only reason they lived.
2. The Wind
For three days nobody went up. The tunnel sensors recorded winds faster than any cyclone in history, the whole atmosphere still rushing east over ground that had stopped beneath it. When the first drone finally went up, it sent back pictures of a scraped, brown city with no roofs and no trees.
To the west, the Arabian Sea had surged east and inland like a wall. The colony's elders called it the Washing. Tara called it the day Newton's first law came for everyone.
3. Six Months of Noon
Earth still went round the Sun, but now it didn't turn, so the Sun barely moved across the sky. One day lasted a whole year: about six months of light, then six months of night.
The survivors split into two groups. The Stayers sealed themselves underground. The Walkers chased the dawn, but the line between night and day crept west at around a hundred kilometres a day near Pune, far too fast to walk. So they rebuilt the old rail line west and lived on trains, always just behind the sunrise.
4. The New Sea
Over the years the water moved. Earth used to bulge at the middle because it spun; without the spin, gravity pulled the oceans slowly towards the poles. A vast dry belt rose round the equator, and two great polar seas grew at the top and bottom of the world.
On the first night of the long dark, Tara climbed out and looked up. The stars didn't wheel round the pole any more. They just hung there, fixed. Her radiation badge flickered amber. The scientists said the magnetic shield was weakening, that the core needed spin. Tara pulled her hood up and walked back to the train.
The end. Now see the science that the story is built on.
See it happen
What would happen, step by step
At the equator, Earth's surface moves east at about 1,670 km/h. If the planet stopped dead, everything not bolted to the bedrock (people, cars, trees, the air itself) would keep going east at that speed. In Pune, at about 18° north, that is still around 1,580 km/h.
The science behind it
Why everything keeps moving
v = 2πR cos(latitude) ÷ 24 h ≈ 1,670 km/h × cos(latitude)
Newton's first law says that a moving object keeps moving at the same speed in the same direction unless a force changes it. You don't feel Earth's spin because you, the air and the ground all move together. Stop only the ground and everything else carries on.
At the equator a point travels Earth's 40,075 km circumference every day, about 1,670 km/h. Further from the equator the circle is smaller, so the speed is multiplied by the cosine of the latitude: about 1,580 km/h at Pune, zero at the poles.
Why the oceans would drain to the poles
A spinning Earth flings its middle outwards, so the planet is about 43 km wider across the equator than from pole to pole. The oceans follow that bulge. Without the spin, the 'downhill' direction for water changes, and over time the seas would flow towards the poles, leaving one enormous continent round the middle.
A day as long as a year
Speed of the dawn line ≈ 40,075 km ÷ 365 days ≈ 110 km per day (at the equator)
A solar day is the time from one noon to the next. Today it's 24 hours because Earth spins. With no spin, the only thing changing our view of the Sun is our orbit, so one solar day would last a full year. The line between day and night would sweep west at about 110 km a day at the equator, less at higher latitudes.
In one line: Newton's first law: moving things keep moving unless a force stops them. Earth's spin is not something we feel, because everything moves with it. Luckily, there is no known way for it to stop suddenly; it is slowing by only about 2 milliseconds per day every century.
More strange thought experiments: Paradoxes →Think about it
A plane is flying west at 900 km/h above the equator at the moment Earth stops. Relative to the now-still ground, which way and how fast is it moving?