I was thinking about the ending of the Superman movie where Superman flew around the planet against its rotation so fast that he got Earth to reverse its spin, which turned back time! :eek:
I was wondering what might actually happen if the planet’s rotation was somehow reversed or even stopped. Would everything go flying off? What would be the difference between an abrupt reversal or stop vs. a gradual one?
Also, what could possibly cause something like this to happen? Could we build continent-sized rocket engines to counter the earth’s spin?
Nothing of any real value to add here (sorry), but didn’t he turn back time because he couldn’t fly fast enough to get two missiles in time. But in order to turn back time, he orbitted the earth several times a second. Which should be fast enough, shouldn’t it?
Always wondered about that when I was little. Still thought that sci-fi had to ‘make sense’.
Your overall speed from the earth’s rotation varies depending on latitude. Near the equator, you’re moving at about 1000 mph. In the mid-latitudes, like in most of the U.S., you’re moving at about 700 mph.
Assuming the earth’s rotation could stop instantly without wrecking the planet (which actually can’t be done), this would instantly launch you at a speed of 700 mph (or whatever) in the horizontal, eastward direction relative to the ground. Probably no good end to that little trip.
The earth’s rotation is already slowing down gradually, very gradually, at a rate of about a millisecond per day per century, if I recall right. That’s the overall long-term trend. There are also short-term fluctuations though when the Earth’s mass distribution changes, and therefore changes its moment of inertia — as happened after the recent magnitude-9 earthquake in the Indian Ocean, which I believe actually sped up the Earth’s rotation a bit.
That’s an engineering question I’m going to have to leave to others. We certainly can’t build continent sized rockets, but I wouldn’t bother. In principle we could build millions of ordinary sized rockets, mount them all over the landscape facing west, fire them all up, and keep them running as long as possible. Offhand I don’t know the numbers well enough (force of thrust, duration of thrust, fuel availability) to know whether we could actually put a noticeable dent in the length of the earth’s day, even assuming we were mad enough to try it.
Someone at the equator is moving at about 1000 mph, so you better stop or reverse it gradually. I’d be worried about the oceans. Think of a storm surge moving inland at up to 2000 mph.
I thought Superman went so fast that he himself went back in time. Just like watching a movie backwards, then, from Superman’s point-of-view, it looked like Earth’s rotation reversed.
He never actually made the planet itself reverse it’s rotation, it was just what it looked like to him.
If he had actually succeeded in reversing the rotation of the Earth, as opposed to going back in time, all that would have been accomplished would be to rip the planet apart.
You nailed it. In the movie, the earth rotating backwards was from Superman’s perspective only. In the comics, Superman and Flash took advantage of their ability to travel faster than light to go back in time. The movie just exploited this ability for Superman to undo some undesirable outcomes by going back in time and altering history. This last bit on changing history was not allowed in the comics AFAIK.
Where do people get the idea that you’d go flying off if the Earth stopped rotating? Gravity is a function of the Earth’s mass, not its rotation. Assuming a gradual slowdown, you’d actually be a little bit heavier once it stopped, depending on your latitude, due to the lack of centrifugal force.
Actually, people originally had the notion that you’d go flying off the earth if it were rotating. They thought the planet was still. That was before Galileo and others came along to explain inertia. I guess people were basing their conclusions from their experiences on carousels or something.
In the OP’s scenario though, the speeds involved (1000 mph or less) are well below the surface escape speed (25,000 mph), or even the low orbital speed (18,000 mph) — so no, you wouldn’t go flying into space if the earth suddenly stopped.
Nevertheless, you would die in some fashion almost as spectacular.
Umm, correct me if I’m wrong here, when you talk about the earth rotating, you’re talking about this thing, right? That is, the rock and magma are spinning, along with the atmosphere, people and everthing else.
The earth doesn’t just sit there and spin below the atmostphere so that if it stopped everyone would go flying off. Even if it stopped abrubtly, you and I’d stop as well.
If you’re asking what if just the solid earth (rock) stopped spinning but everything else on the surface kept moving, that’s kinda silly? It’s like asking, “What if in my car driving down the freeway, the passenger seat stopped moving or reversed direction?” I suppose a better analogy would be what if the medal car chassis stopped moving. Answer: so would everything else.
I think the real question is: What would be the environmental implications (tide, sun, weather, etc.) if the earth stopped/reversed.
Go out on the highway in your car. Put a big tall glass of stinky spoiled milk on the passenger seat. Get up to 55 MPH, then slam on your brakes. According to your post, you won’t be cleaning stinky spoiled milk off the floor, since the glass will stop too.
When you’re finished cleaning up the stinky spoiled milk, post back here.
I suppose this depends on exactly which (impossible) scenario the OP was asking about here. He asked, “Would everything go flying off?”, which suggests to me he’s proposing the bulk of the planet to stop, leaving everything on the surface to its own, separate fate.
But sure, if you’re magically halting the entire earth, you might as well extend the magic outward just a little bit more and halt everything else too. That’s just good common sense.
OK, so my interpretation of the question is: what are the real effects of the direction of the Earth’s rotation?
Or, assume an alternate Earth that’s identical, except spins in the opposite direction. If you were magically transported there, what differences would you notice?
My thoughts: First, and most obvious, is the run rising in the west and setting in the east. Though the major changes wouldn’t be that great: some buildings and gardens might be laid out so as to catch the sunset in the opposite direction, but generally north-south is the major concern, not east-west. Japan would no longer be the land of the rising sun, and left-handed pitchers would be northpaws instead of southpaws, and probably a few other cultural changes.
But the more important change is that all weather patterns would be reversed east-west. So the prevailing winds over the north half of the U.S. would be east to west instead of vice versa. This would have huge, huge, huge effects on the weather/climate/landscapes in many many areas. For instance (these are wild guesses on my part, not being a climatologist) Washington and Oregon coasts would probably be just as dry as eastern Washington. Possibly the great plains would be wetter (i.e. great forests). Because the Gulf stream would flow differently, Europe would be much colder, etc.etc.
The earth’s magma might have a co-rotating component to it, but I think that its magnetic field generation comes mostly from convection currents unrelated to that motion. (I’m not a geologist; I’m going by what I’ve read here and there.)
In any case, the earth’s magnetic field comes and goes from time to time, and even reverses direction entirely, despite the planet’s fairly constant rotation. So we know that the rotation itself isn’t all that important — not to the magnetic field anyway.
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[li]Panic[/li][li]Destruction[/li][li]Profit! (from some huge clean up and remodel contracts)[/li][li]Bozoooo finally gets his GQ answered.[/li][/ol]
