World
What If Earth Stopped Spinning?
Short answer: anything not fixed to rock would keep its eastward speed, about 465 metres per second at the equator, and the new day would last a year. A slow stop is gentler but ends in the same place. Pick your latitude and how fast it stops below.
What happens if Earth stops rotating?
Earth is not sitting still. It turns once a sidereal day, which at the equator means a point on the ground is already travelling at about 465 metres per second toward the east. That motion is usually invisible because the air, the oceans and the crust all share it. This experiment asks what happens if that shared rotation is removed, either over hours or over a year, at a latitude you choose. A sudden stop is a thought experiment: unsecured objects, and the atmosphere if you leave it in the model, keep their eastward speed. A slow stop is gentler but still ends in the same place — a planet that no longer presents a new face to the Sun every 24 hours. The new day is a year. Poles and equator do not have the same story.
Written and checked by Aivora Digital · Last updated:
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Shorter times are a sudden-stop thought experiment.
51.5° is roughly London; 0° is the equator.
If on, air retains its eastward speed as a wind.
Your result
290 m/s
eastward speed at 51.5°N
ground and air currently share this motion
- Leftover eastward speed
- 289.5 m/s
- Westward acceleration while stopping
- 0.0034 m/s²
- New length of a day
- 365.3 current days
- Centrifugal relief you lose
- 0.0131 m/s²
- Atmosphere in this run
- keeps moving east
1,042 km/h
0.03% of g
0.13% of g
What does that mean?
At 51.5°N the ground is moving east at 290 m/s (1,042 km/h). Removing that motion in 24 hours implies a westward acceleration of 0.0034 m/s² (0.03% of g). Spread over this long, it is a slow drift rather than a shove. The air still has that eastward speed, so the first weather is a 1,042 km/h wind toward the east. After the stop, a 'day' is 365.3 current days — one trip around the Sun. Apparent weight increases by 0.13% as the centrifugal relief disappears.
At a glance
- Your leftover speed290 m/s
- Equatorial speed465 m/s
- Typical airliner cruise250 m/s
Timeline
t = 0
Brake starts
Spin is still a sidereal day. At 51.5°N the shared eastward speed is 290 m/s.
24 hours
Rotation reaches zero
The ground has stopped. Air and sea still have ~290 m/s of eastward inertia — a global jet, then chaos we do not simulate.
After one orbit
First 'sunset' of the new calendar
Without spin, the Sun's apparent motion is the yearly orbit. One hemisphere has just spent a season in light.
Geological time
Figure of the Earth
The equatorial bulge would slowly relax. Oceans would seek a more spherical geoid. This page does not run that calculation.
Compare
| Equator | 465 m/s | 1,674 km/h |
|---|---|---|
| 51.5°N | 290 m/s | this run |
| Pole | 2.85 × 10^−14 m/s | cosine goes to zero |
Compare scenarios
Sudden stop versus a long brake
If the ground halted in minutes, anything not attached to rock would keep the eastward velocity it already had. At mid-latitudes that is still hundreds of metres per second; at the equator it is faster than a jet airliner. The atmosphere and oceans, if they are included, become a worldwide eastward gale of the same order. Stretch the same change over months or a year and the westward acceleration drops below anything you would notice as a shove. The destination is identical: zero spin relative to the distant stars. Only the ride changes.
A day that lasts a year
With no rotation, sunrise and sunset are set by the orbit around the Sun, not by a spinning globe. One face of Earth would spend a long season in daylight and the opposite face a long season in night, with twilight belts that creep as the year proceeds. Weather, photosynthesis and habitability would reorganise around that slow illumination. This model does not simulate a new climate. It only points out that the 24-hour clock is a rotation effect, and rotation is the thing you just switched off.
Where you stand matters
Tangential speed falls with the cosine of latitude, so a polar observer has almost no leftover eastward motion to keep. An equatorial observer has the full 465 metres per second. Apparent weight also changes slightly: today, rotation shaves a fraction of a percent off g at low latitudes through the centrifugal term. Stop the spin and that small relief vanishes. Over geological time the equatorial bulge would relax and the oceans would seek a new level. That last part is not instant, and this page does not reshape the solid Earth.
Common questions
What would happen if the Earth stopped spinning suddenly?
Anything not fixed to rock would keep the eastward speed it already had: about 465 metres per second at the equator, and still hundreds of metres per second at mid-latitudes. If the air keeps that speed too, it becomes a worldwide eastward gale.
How long would a day be if Earth stopped rotating?
A year. Sunrise and sunset would follow Earth’s orbit round the Sun, so one side would have a long season of daylight while the other had a long night.
How we calculated this
Present angular velocity is 2π divided by the IERS sidereal day, applied to the WGS 84 equatorial radius. Eastward speed at a latitude is that equatorial speed times cos(latitude). Stopping is modelled as a uniform slowdown over the chosen duration, so the westward acceleration is simply v / t. If the atmosphere is included it keeps the original eastward speed as a wind; if not, only the ground is braked. The replacement day length is one sidereal year. No hydrodynamical ocean, no elastic Earth, no climate code.
Assumptions and limitations
This is a simplified estimate. Actual results depend on factors the model does not include.
This is a simplified thought experiment. It uses transparent assumptions so you can see what changes — it is not a full physical simulation of the real world.
- Earth's present spin is the IERS sidereal day, not a mean solar day.
- Stopping is a uniform angular deceleration over the chosen time; it is not a physical mechanism.
- Unsecured objects and, optionally, the air keep their original eastward inertial speed.
- The solid Earth does not instantly shed its equatorial bulge.
- Orbit around the Sun is unchanged, so a non-rotating Earth still has a year.
- Local g is the standard 9.80665 m/s² minus the centrifugal term that rotation currently supplies.
Sources
- NASA Earth fact sheet
Mass, radius, rotation period and orbital speed used as the baseline Earth.
- IERS — Earth rotation
Sidereal day used to set Earth's present angular velocity.
- NOAA NGS — WGS 84
Equatorial radius used for surface speed and centrifugal terms.
- NIST CODATA — standard acceleration of gravity
gn = 9.80665 m/s², the conventional standard gravity (also ISO 80000-3).
Go further
Related experiments that pick up where this one leaves off.
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