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What would happen if the Earth slowed down and stopped turning altogether?
Question
#81287. Asked by darkpresence. (May 31 07 4:11 PM)
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Baloo55th
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Assuming it didn't happen instantly - which could only happen with a super-giant tractor beam or similar SF tool - the day would lengthen until it took one year for a day. Daytime would get very hot, and nightime very cold. The Earth wouldn't be in the situation of Mercury, with one face towards the Sun at all times, because Mercury actually revolves at a speed that allows this. The apparent speed of the Moon would change, too, but I'm not sure in what way. In the SF scenario, if the surface was stopped there would be vast earthquakes as the core carried on - but we wouldn't be flung around by the stopping as the beam would affect us too.
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laker21j
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The force that keeps your feet on the ground called gravity would cease to exist and off you will go.
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Baloo55th
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Gravity would continue, as it is a function of mass not of rotation. Pseudo-gravity can be created by rotation in spacecraft but that is what used to be called centrigugal force, and you have to be on the inside of the curved surface to experience it.
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davejacobs
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See the short story by H G Wells, The Day the Earth Stood Still.
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sequoianoir
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Sorry Baloo but the bit about
" the situation of Mercury, with one face towards the Sun at all times, because Mercury actually revolves at a speed that allows this"
is incorrect.
A guy called Giovanni Schiaparelli thought that a Mercurian day was the same as a Mercurian year, namely 88 Earth days, and accordingly would be in a "gravitational lock", just like the Moon around the Earth with the same side always facing. This was accepted from the 1880's until as late as the 1960's.
In 1965 radar measurements proved it actually rotated in 58.6 Earth days.
Whilst Mercury is not in "gravitational lock" it IS in "GRAVITATIONAL RESONANCE" where its axial rotation is two thirds of its orbital rotation.
This equates to a Mercurian year being one and a half Mercurian days long.
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Baloo55th
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Near enough. The point I was trying to make was that it's not static rotationally, and that we wouldn't have one face to the Sun all the time.
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sequoianoir
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Yes it would have to rotate (just once in a whole year)to maintain the same aspect facing towards the Sun.
The best example of this "lock" of course is the Moon which rotates just once in 28 days, the same time it takes to orbit the Earth.
If the Earth had zero rotation, it would not be fixed, in each 24 hours approximately 1 degree would change from day to night and vice-versa. "Day-time" would last 6 months, as would "night-time".
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sequoianoir
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Just for correctness, of course the lunar month & rotation period is just under 27 and one third days
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billythebrit
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Would we fall off?
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richard_n413
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The force of gravity and the rotation of the Earth are two separate things, so we wouldn't just "fall off the face of the Earth".
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Baloo55th
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Gravity is to do with mass, not rotation, vacuum, linear motion. All bodies exert gravitational force (to put it in a rather simplified and dated way). In fact, the doctor or midwife present at your birth exerted more gravitational force on you than the planets! The only change in our personal motion would be, as I said, if the Earth's surface stopped instantly. Then we would fall over, but not off. The gravity exerted by the Earth would keep us from flying off into space. The speed of rotation of the Earth's surface (even at the Equator) is less than the speed needed to leave the Earth's gravity, so even if we did go up a bit, we'd come down again.
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Bobjegers
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Do you think we would experience a greater amount of gravity due to the ceasure of the rotation of the Earth?
as Baloo said, "Pseudo-gravity can be created by rotation in spacecraft but that is what used to be called centrigugal force, and you have to be on the inside of the curved surface to experience it."
In my mind anyway, logic would follow that on the outside of a curved surface, we would experience a slight amount of force pushing us off the Earth in tangent direction...
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Baloo55th
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No. The gravitational force is proportional to the mass of the bodies concerned, not the rotation. Gravity isn't just what keeps us down, it's a mutual attraction. (Hi!) You attract the Earth awhile the Earth is attracting you. The thing is, the Earth is so much bigger that the movement you cause it to make is so tiny it can be disregarded. (I'm saying nothing about those people in Australia who are attracting it the opposite way from us in the UK.) If you dug a lot of the Earth up and threw it into space, the gravity would decrease. But... You'd have to shift one heck of a lot of it before even the most sensitive instruments would notice. This is why when you walk past that obese 27 stone jerk from No 46 you don't veer off course towards him. Out in a gravity null location (and wearing spacesuits), you might feel attracted to him in a gravitational sense. Down here, no way. (Possibly in either way - depends on taste...)  http://en.wikipedia.org/wiki/Gravity
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Baloo55th
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As to the reverse of 'centrifugal force', that would seem logical but... The pseudo-gravity of the rotating spaceship is produced solely (OK, 99.999%) by the rotation. It's an illusion in some ways. The attraction by the Earth is not caused by rotation in any way. It's the mass of the planet that does it. Cancel out the mass somehow, yes, we'd go flying off gracefully or otherwise. But... can't be done. Not with the highest technology available or conceivable within our lifetimes. (Although if one can conceive of greater technology....)
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Bee8090
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Baloo is very right about the whole gravity thing, however that would not be the main concern if the world stopped turning. The days would be 6 months long and extremely hot and the nights would reach temperatures near -67 degrees. The oceans would all concentrate themselves to the north and south poles freezing at the northern and southern most points of the earth. As for the continents there would be only one running along the equator because of the movements of the oceans. on top of that there is the weather patterns to consider, as the rotaion of the earth makes our weather pattern very predictable because of the Coriolis Effect (the direction of the winds in the northern and southern hemispheres) all weather patterns would cease to exist. wherever the sun casts its "spolight" on earth as it rotates around the sun there would be bruttle storms that humans would not be able to survive. our lives would completely change and the world would end as we know it. the planet would of course still remain but its whether or not people and animals will have the ability to adapt fast enough to the changes.
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