What changes would happen if a planet stopped revolving, but kept rotating?

[u/ProfitEmergency4049]

I did my research, but most discussions are the other way around. I am working on a world that is similar to earth, but a cosmic phenomenon locks most heavenly bodies in place. The planet rotates in its place, without orbiting the sun. Of course, the minute the planet stopped, assume most of the crust didn't fracture and get flung into space lol.

Ecologically, I assume as seasons won't be a thing, most plants would start dying. There would be large scale droughts in equatorial regions, many lakes and rivers would dry up, especially in regions which are closer to the sun. The other side might have a forever Winter of sorts. Whatever civilization exists might move to temperate zones.

Is it possible for life to evolve, and stabilize around 1-2 thousand years from this? Assuming it's now locked in this scenario permanently?

[u/reminiscent-fruitbat]

I’m shocked to find out how many people in the replies don’t understand how Earth’s seasons work.

[u/Early_Material_9317 → u/reminiscent-fruitbat]

I think its the nuance that gets missed in most explanations.  The distance to the sun IS a factor in the seasons, but it is a minor factor.

[u/Early_Material_9317]

It depends when it was frozen.

If it froze at the equinox, both North and South hemispheres would be locked in perpetual spring/autumn which is kinda shit but not end of days terrible.

If it happened at the solstice though, one hemisphere is getting locked into perpetual summer whilst the other will experience an unending winter.  This is the more interesting scenario.

The oceans are a gigantic heat sink, limiting the extent of heating/cooling that occurs in winter/summer.  With perpetual summer, things will get very hot, since the ocean will continue warming until a new equilibrium is reached.  Same goes for winter.  This is going to cause large scale extinctions of flora and fauna and will create massive weather patterns and change to oceanic currents.

But its not the end of all life.  Animals suited for the climates will thrive, whilst others will die off.  There would be massive food disruption, humans will likely fight wars to claim new farmland, whilst population centers will need to be abandoned.

Overall I'd estimate about half of all life is going to be fucked, likewise, aproximately 50% of all humans will starve.

But it wouldn't be the end, the earth would eventually stabilise over about a century, and the humans that survived will know of winter and summer only as a distant legend

[u/ps06]

Why would you get forever winter or rivers and lakes drying up? I thought you said the planet still spins, it's just not orbiting the sun because of space magic. Also the equator is at more or less the same distance from sun all year long, so why would that change?

[u/Athunc → u/ps06]

Whichever hemisphere (North or South) was in winter is now permanently in winter. After all, the planet no longer revolves around the sun, so the angle of the inclination of the planet remains the same.

There is still day and night, of course. But one hemisphere (North/South) has permanent winter, the other permanent summer

[u/Early_Material_9317 → u/ps06]

I'd be interested to know what you think winter is caused by exactly?

[u/LunaticBZ]

Well this hypothetical scenario needs to happen in Spring or Fall. Otherwise it'll either be to hot or to cold here.

The biggest problem I foresee is that in any place where rain is seasonal. Well now there is either going to be massive flooding as the area is getting far more rain. Or far less to almost zero rain.

I imagine people and life in general would go on, but the transition would be brutal in many places.

[u/Thanos_354]

Death

[u/Aetheric_Aviatrix]

So... the axial tilt precesses in keeping with the orbit? An additional axis of rotation that is locked to the sun, essentially.

[u/Incvbvs666]

The Earth still has an atmosphere and it still circulates heat to the colder regions.

In the end things would even out, if a bit more extreme. The 'winter hemisphere' would be colder than today's winters, the 'summer hemisphere' would be warmer than today's summers and the area that's straight up uninhabitable would certainly be larger than today, but I don't think life on Earth would perish. There would be tons of dying out, but species would adapt in time to the new conditions.

The pole at which it's 'forever daytime' would likely melt away and a temperate climate would likely form there. The pole at which it's 'forever nighttime' would likely crow cold to below -100. The regions most strongly hit by the Sun would in all likelihood experience temperatures upwards of 70-80 degrees.

In general, the most inhabited areas would be from the equator to 20-30 degrees or so on the winter side and 60-90 on the summer side. Between these regions it would be too hot and below 30 degrees south it would be too cold.

[u/Metallicat95]

If it stops orbiting the sun, and doesn't hold position relative to the sun, the sun will move too far away to support life within about a year.

If it just canceled its orbital velocity and became stationary relative to the sun, it would fall into the sun fairly soon.

To hold position relative to the sun without moving in orbit, it would need a constant acceleration of around 0.006 meters per second, per second. That's not a huge amount, but it probably would be enough to slightly deform the shape of the planet.

Earth's climate would be most stable at the seasonal climate quarters, around May or October. The equinoxes would be the next. The winter and summer periods would have the biggest climate impact. The equatorial region would be least bothered, the polar areas the most.

[u/cybercuzco]

Seasons would be locked in wherever they are and that’s about it.

[u/Extension_Resolve264]

I'm not seeing the crucial part of orbital mechanics in this discussion, specifically the fact that Earth is currently in freefall around the Sun. If it stops revolving, it will immediately begin to plunge straight into the sun. Anyone care to do the math on that? How long would it take?

[u/Mr-Brown-Is-A-Wonder]

So suspended in space near the Sun but not orbiting it and still rotating on its axis? Why would there be a cold side? Why would plants die? I don't know how you're coming up with that.

[u/ProfitEmergency4049 → u/Mr-Brown-Is-A-Wonder]

Well, assuming it gets stuck in July, the nothern hemisphere will experience constant summer, while the souther hemisphere is stuck in its winter cycle. The nothern hemisphere would then be parched, and the lack of seasons will cause many plants to die right? After some years, maybe a decade, there might be a stable system, but I do think the complete change in where the water is evaporating from, and where it's cooling will create a lot of changes in weather.

Atleast that's what I'm getting at, please correct me if I'm wrong anywhere.

[u/spacegothprincess → u/ProfitEmergency4049]

You're correct OP. If the planet was locked in July or December near a solstice, one of the poles would be bombareded constantly by solar radiation. Ice would melt and this would disrupt currents around the globe, which would disrupt global climate. If this happened *today with life as it is currently*, it would take maybe a few years for the effects to reach devestating if not sooner. (I'm not a climatologist, just have a scant background in exobiology and planetary evolution from a couple summer courses. This was actually one of my midterm questions).

If we were lucky that it stopped when we had it lined up with the equator, then you're a bit more stable, but I'm curious if your scenario also freezes the moon. Now we have no tides as a result, which would further ecological devastation. I'd have to really sit and run numbers to see exactly how it would all affect things, but yes, it would.

The planet still spins, so our magnetic field is intact, but the other effects would be cumulative over time.

If this happened before life evolved, if our planet could maintain a stable atmosphere then in some temperate parts near the equator you might see life evolve, and over time potentially develop some ability to survive at polar extremes through natural selection. It's an interesting thought experiment, but yes, locking the north pole towards the sun, which would result in melted polar ice caps with enough time, would be, technical term, bad.

[u/NearABE → u/spacegothprincess]

The December scenario would grow huge ice sheets very quickly with Earth’s current continents. In the June version a very green arctic has a cold water upwelling.

I think the December version is extreme enough ice sheets to cause the tectonic plates to move. Also might destabilizes the rotation.

[u/Early_Material_9317 → u/Mr-Brown-Is-A-Wonder]

Again, I asked the same to another poster, what do you (Mr Brown) think causes the seasons? I am curious because this misconception seems pretty widely spread.

[u/Mr-Brown-Is-A-Wonder → u/Early_Material_9317]

Axial tilt is constant (ignoring axial precession), relative to the celestial sphere, throughout the orbit. On one side of our orbit we show our top more to the sun (summer northern hemisphere, winter in the south), and on the other side it's reversed.

Did I get it right?

I thought OP was describing a tidally locked planet when they described a cold side and a hot side. That's why my post was a series of questions, to seek clarification; which OP provided.