Earth has stopped rotating. Maybe Superman started flying around the Earth backwards to turn back time, but hit a wall of kryptonite just when the Earth stopped rotating. Or Stupendous Man hit the earth so hard that it went from Sunday to Saturday... but also has stopped the earth's rotation. Let's also say that the rotation stopped slowly - not all at once. Slow enough, anyway, so as not to cause city-leveling winds.

Note that the earth is not going around the sun such that the same face of the earth is always facing the sun. I imagine it like a model solar system...say you pinch the earth model between your fingers at its poles, and then while standing in the same position, crank it around the sun. So, a day on earth lasts 12 months. Watching the sunset over the ocean could take you about 3 months.

So what would be some effects of the earth's rotation stopping like this?

First meteorologically: I imagine that the weather would be drastically different...but how so? Would storms be much less violent? More violent? The sun over the ocean would have months and months of virtually uninterrupted time to evaporate the surface water. Would this build the clouds so much that storms are still frequent? What about cloud coverage as a result - would clouds be so thick from that much uninterrupted sun, that they would in effect shade the earth? The Coriolis effect would be almost non-existent, right? This would effectively slow storms and wind from moving along the ocean...but wouldn't they still build? What would such a storm be like when (if) it reached land?

How about land-locked areas? I imagine there would be many more deserts, and really, the most inhabitable places on earth would be close to coastlines. Basically climates seem like they would be quite different...but how?

And then what about the seasons, as we know them? Would seasons still follow the same quarterly pattern, along with the day/year?

What about other geological effects? Plate tectonics: earthquakes, volcanoes, etc? Or the earth's magnetic field...any effect there? Many other geological processes depend on the weather, so I guess this answer depends on the weather question above.

Biologically speaking, how would humans and other organisms survive? I suppose humans are pretty resilient and innovative, so living in the sun for 6 months and in the dark for 6 months, we'd find a way to make it work. But what about other animals? Circadian rhythms would be all messed up.

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    Thanks Seth. Do please feel free to ask that as a separate question (you can cross-link the questions). – Monica Cellio Feb 20 '15 at 18:11
  • @seth - remember the Earths magnetic field is dependent on this rotation...It'll be weaker at very least, potentially no existent. This opens up the inhabitants of your world to some brutal solar rays and other radiation that life here couldn't survive. – Twelfth Feb 20 '15 at 19:01
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    This was addressed in the XKCD what-if book. I own a copy, and let me tell you that if is one of the best books I've ever read. It's not quite fiction but not quite non-fiction. It is science and statistics and extrapolation. If you are asking this question, then you will absolutely love the book. – dotancohen Feb 20 '15 at 19:28
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    The XKCD What If can also be found here but it focuses on the Earth suddenly stopping as opposed to the the long-term effects. The good news is that the Earth would speed back up again thanks to the moon but it'd be... slow. – Engineer Toast Feb 20 '15 at 21:18
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    Does "stopping the crust" also entail stopping the inner rotation of the core? If the core kept spinning, it might spin up the Earth again. Ditto for the moon. – user3082 Feb 21 '15 at 7:35
up vote 26 down vote accepted

Bad things. Lots of bad things.

First off, there is a term for the version of "not rotating" that you're after. You're looking for it to stop rotating in the sidereal frame. The sidereal frame is what you would see if you looked at the earth from one of the constellations. The Earth is not rotating about its axis from this perspective, but you will see a year-long day/night cycle.

You are right about how the Coriolis effect will basically be out of play. Your angular rate drops from $7.272 × 10^{-5} \text{rad/s}$ (Earth's current rotation rate) to $2.042 × 10^{-7} \text{rad/s}$. The Coriolis term is directly proportional to this, so expect to see a roughly 300x decrease in the effects of the Coriolis effect. All of our nice predictable weather patterns which rely on Coriolis to create easy to work with atmospheric cells go out of the door. Fortunately, we're going to make new ones.

Our temperature balances all center around the day/night cycle. You would basically be removing that from play. Life is about to get really miserable. You're going to have a hot spot on the Earth, wherever it is day. This is going to create a large mass of hot air rising very quickly off of the plains. This air will be displaced by air from the twilight regions of the planet. Large, very angry convection cells will form.

How angry? Well, consider the part of the planet most directly in line with the sun. The only air cooling it gets is going to be from the hot air rushing in nearby. All of the cold air from the twilight regions is going to be heated up as it travels over the rocks (it stays low because it's cold air). This heats the air up, causing it to lift away. You won't get one big convection cell the size of a planet. You'd get dozens, each one hotter than the next.

And in the middle? Well, let's just have a reminder of how hot the Sun is. Build a solar oven. You use mirrors to increase the power of the sun by maybe 4x, and then you isolate the hot box from the outside world. The isolation is actually the important part. If you could get nice insulating glass, you could cook food without needing mirrors at all. Solar radiation is $1.4\text{kW}/\text{m}^2$. Each square meter of land is getting more solar energy than a commercial grade microwave on "high". There's a reason you can cook your food this way!

The temperature gradients probably wont let you get to "glowing," because at that point the equations get more interesting (you start radiating energy out into the cold of space, which keeps you cool). However, temperatures will easily reach oven temperatures, without any trouble.

On the other side of the planet, you have several months where you cannot see the sun. At this point, radiation of thermal energy will come into play. The sky is roughly $-40^\circ\text{F}$ You're going to be dumping a lot of energy into the sky. Consider a desert where we have clear skies (clouds make the sky "appear" warmer). It is not unheard of to have a nice 60°F day (15.5°C), but when the sun goes down, the radiation effects emit so much heat into the cold sky that you can wake up to find ice on the ground. This happens over the course of a few hours. Imagine what 6 months of that would do.

Unlike the hot side of the planet, we don't get convection cells here. The cold ground chills the air, rather than warming, creating a layer of cold air near the ground. With such a smooth temperature section of the globe, there won't be much wind to disrupt the wind. The only effects we will see are radiative. And, since there's no wind, there's nothing to push moist air into colder regions to make clouds. It would just be a cold cold cold desert sky for months on end. At some point, you would start to chill the atmosphere enough to see a sky that appears to be even colder than $-40^\circ\text{F}$.

So what does this mean for geology? Even the rocks are going to have a hard time. One of the most powerful erosive forces in the world is ice. Water seeps into cracks and then later freezes. The expansion of ice breaks off huge hunks of rock. Temperature gradients like this one are going to give ice a run for its money. A yearly expansion-compression cycle of 500+ degrees is going to cause anything resembling a hard rock to crack into dust. The surface would be littered with only soft materials that can flex. Mica might be a good example, as would clay.

However, the soft materials won't have a good time either. Consider the windy seasons. Yes, seasons. Twice a year, your particular spot on the globe is going to be in the twilight, on the edge of the strongest convection cell on the planet. Massive winds are going to pound you from above. On the leading edge of the hot zone, you'll get torrential downpours because the heat will evaporate the water that deposited when it got cold. It will be flung high into the air to turn into massive rainclouds the likes of which the world has never seen. This wind and rain would pummel any soft materials into dirt. Since the world has lots of dirt, the edges of these convection cells will create massive multi-kilometer high dust storms.

What about the poles? They fare better. The closer you get to the poles, the more time you spend in twilight. However, most of the nasty wind/rain effects are going to be found along east-west lines. You'll get less of it in the north and south. Unfortunately, there's a problem here too. These are still the poles of the Earth. They still only get glancing sunlight, so they are just as cold as the Arctic or Antarctic is today!

I want humans to survive in this!

You are a sick individual for subjecting your citizens to this world. Your best bet is to invent space travel and get off this rock before Superman stops its rotation!

No luck? Well drat. Okay, it's survival time.

There is no way to survive at equatorial latitudes. There simply isn't. Unless you are an amazing ocean-faring race, there's no way to just keep outrunning the hot zone. Once it hits you, it's over. Digging holes might work, but the fracturing rock makes it likely you wont be able to dig yourself out before the cold hits. Just like nowadays, surviving at the poles is not an option.

The solution is to live on a belt just below the arctic. The Inuit might not even notice that the earth stopped spinning. They live with months of no sun already. They would, however, notice that the winds are getting trickier to deal with.

A little further down, you might be able to have a band of nomads which continuously circle around the world along the twilight. These are the regions that are getting subjected to extreme conditions, so you wouldn't get to stop moving. You would have to stay with the twilight. Land bridges would be key.

What survives on this planet? Well, along that magic band, plants may be able to wait out the winter and quickly thrive in the windy seasons. There would be abundant food if you found these. Plants would have to spend so much energy reproducing each year that they wouldn't be able to stop you from eating a little without seriously jeopardizing their survival. Arctic water creatures would fare well. If you had a sufficiently flat world, there might even be a river system which equatorial creatures could use to traverse across continents (I'm thinking of the most epic whale migration imaginable).

In all, it's a bitter world to live in.

  • Ahh sidereel! I've heard that before. Thanks! – Seth Feb 20 '15 at 19:31
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    I'm pretty sure the word is sidereal -- searches for sidereel just yield some TV watching web site. – Gabe Feb 20 '15 at 20:01
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    I'm fairly sure you don't mean -40 Kelvin for the temperature of the sky, right? Is that supposed to be -40F or -40C or something? – Erik Feb 20 '15 at 22:11
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    Also, there is a very good reason why the magnetic axis of the earth roughly aligns with the spin axis. Stop the spin and you quickly (less than 100 years?) dissipate the magnetic field, along with the Van Allen belts that protect us from the sun's UV+ radiation. Think Venus. – Pieter Geerkens Feb 21 '15 at 5:11
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    @user3082 a human could out-walk it, but an entire culture would have trouble if it couldn't root somewhere. Food and water would be important (water would be interesting because, at a walking pace, you would have to find a perfectly straight east/west river to quench your thirst, or move faster than walking to follow a real river). Also, consider: the oceans are not your friend. – Cort Ammon Feb 21 '15 at 15:49

This is some question. There really needs to be another qualification associated with it as well that yields drastically different outcome. Does the earth stop spinning slowly or quickly, in comparison to geologic spans. If quickly, the earth's crust does not have time to adjust the equatorial bulge and the oceans will collect towards the poles, draining away from the equator. If slowly, the equatorial bulge could stay in equilibrium with the actual spin and the oceans could remain essentially in place. Long term, the bulge will disappear in either case. Of course if you stop it suddenly, you have a new class of problems as the atmosphere (and possibly the oceans) are still traveling up to 1000 miles per hour when you stop the planet. 1000 mph winds would come pretty close to destroying the planet by themselves.

For simplicity, I am generally ignoring effects related to stopping the rotation quickly, i.e., assuming stopping to take 100K years or so.

Weather -- 1 day = 1 year means very bad weather indeed. Peak daytime temperatures would perhaps be at a guess 70 C / 170 F -- black body radiation being proportional to the 4th power of the temperature. Dark side would be colder that current Antarctica since it would be 180 degrees around from noon, not just 23 deg. away from the terminus (the day/night separator). Carbon dioxide would freeze out of the air. Virtually none of the existing plant and animal life on the earth would be able to survive these extremes. Of course, the sun now rises in the west and sets in the east.

The polar regions would be near the terminus, but due to the large temperature differences between day and night would be subject to extreme winds and storms as the atmosphere would continually migrate from the day side to the night side. The winds would never let up., so agriculture would be virtually impossible and plant life nearly non-existent as well.

Wind circulation patterns would be completely disrupted. Current deserts generally result from the air being squeezed dry by passing over mountains, i.e., in prevailing westerly winds on the east side of the mountains. With a 24 hour year, the prevailing winds would be easterly part of the year, westerly at other times. But most of the precipitation near the terminus where you are passing to the night side -- inconveniently when most vegetation cannot use it productively.

As the earth slows down, earthquakes would be large and widespread as the equatorial bulge disappears. Long term, the there would not be the mantle currents thought to cause crustal drift that powers earthquakes. The magnetic fields would disappear too, hello radiation coming from the sun as the ozone layer is destroyed. Longer term, the atmosphere would disappear more rapidly during the the higher daytime temperature, but this would be a very slow effect.

Not much that lives would survive this change. Humans no doubt would be able to grow food in their bunkers via hydroponics, etc. but it would not be a pleasant life. If the stopping time was very short, nearly everyone would be killed in the initial trauma caused by the severe winds of course and humankind may not be able to survive at all.

For prior art, be sure to read Joshua 10:12-14. The account is sorely lacking in details however.

Earth’s Rotation Essential for Survival

Most people don't really appreciate just how essential Earth’s rotation really is for human survival. They merely consider it a way that God or nature provided in order for humans to have time of rest after a hard day’s work. But there is much more involved in Earth’s rotation than meets the eyes.

The stark reality is that if the Earth were to stop rotating, either via a gradual or sudden process, mankind’s survival on the Earth’s surface, along with that of animals and plants would become an impossibility.

Here are some of the very nasty things that would occur if the Earth stopped rotating.

  1. The atmosphere: Presently Earth’s atmosphere seems evenly distributed. But if Earth stopped rotating, the atmosphere would surge towards the poles. Doesn’t sound all that bad does it? That is until we consider the effects this would have on the rest of the planet. You see, such a surge would leave other parts of Earth with an atmosphere too thin to breath. An atmosphere similar to that which we might encounter at very high altitudes. So those people living there will either relocate or suffocate. But the question is-Relocate where? since other changes would have made relocation extremely difficult if not impossible for millions.

  2. Oceanic Effects

    Not just the atmosphere but the mighty oceans would surge towards the poles as well, flooding cities and densely populated areas in the process and creating deserts in other areas it abandons. The result? A huge virtually uninhabitable continent that girdles the earth like a belt would be created.

  3. The weather

    Day and night as we know it would cease. Each would be a year long. As one-half of the Earth becomes constantly exposed to the darkness of space and the other to the heat of the sun for a year, extremely hot and cold temperatures would ensue. Earth’s night side would plunge to 60 below zero while the daylight side temperatures would also rise extremely high.

  4. Magnetic Field:

But this is not all. We humans take for granted that we are safe on Earth’s surface. But such safety is only made possible by Earth’s magnetic field. You see, contrary to how peaceful things might seem, Earth is being constantly pummeled by cosmic rays and other particles from the sun that are deadly to life.

Fortunately, these particles are deflected by Earth’s magnetic field which is generated by the the constant flow of Earth’s molten core. But once the core becomes stationary, Earth’s magnetic field will founder and all this radiation radiation will reach the surface. Only underground living would be possible.

Not a good thing to happen by any standards.

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  • Why would atmosphere and ocean surge to the poles? – L.Dutch Dec 9 at 5:20
  • @L.Dutch For the same reason that the land would surge to the poles: The loss of the centrifugal force that flattens our planet. Of course, this flattening applies to air, water, and land in the same way (the earth behaves more like a ball of water on these scales), so I doubt that you'd run out of breathable air at the equator. You'll likely get some nasty earth quakes during the adaption period, though. – cmaster Dec 9 at 17:59

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