Why Does Earth Keep Spinning Around the Sun?

[Raza]

It seems like a childish question, but why does the Earth go around the sun? Why not stay in a single place?

 

[russ_watters]

It can't stay in a single place because of the force of gravity. It has to either orbit the sun, fall into it, or fly away from it.

 

[arildno]

Of course, in the Earth's rest frame, the Earth is, indeed stationary. At all times..*




*I know, it is dumb, but I couldn't resist posting it anyway..

 

[Averagesupernova]

Of course, in the Earth's rest frame, the Earth is, indeed stationary. At all times..*




*I know, it is dumb, but I couldn't resist posting it anyway..

The Earth is flat too.

I'm just jerk'n your chain. As with you, neither could I resist posting.

 

[complexPHILOSOPHY]

The Earth is flat too.

I'm just jerk'n your chain. As with you, neither could I resist posting.

Reserve the jerk'n for a special occasion.

 

[Raza]

It can't stay in a single place because of the force of gravity.

I still don't get of why it must orbit around the sun.

 

[russ_watters]

Could you explain more about what you don't understand...? If you pull on a door handle, why does it open?

 

[americanforest]

The planets and sun came from a slowly spinning mass of cosmic gas. Since angular momentum has to be conserved now the planets go around the sun. I'm no astronomer so the description might not be perfect, but it's generally true.

 

[ranger]

When we drop something to Earth from a reasonable height, it falls to the Earth in a straight line. If we however were to stand and throw a ball at a certain angle, it will fall to the Earth along a curved path. If it were possible for us to throw it hard enough, the ball will follow a curved path, but would always miss the earth, hence it would be falling to the earth, but always missing. Therefore, it is in orbit around the earth.

The same principle can be applied to the earth. It is falling towards the sun, but it moves sideways fast enough i.e enough tangential velocity to always miss the sun. Like the ball in orbit around the earth, the Earth is in orbit around the sun.

 

[Wizz]

Nice one Ranger. Simple and short. Now he should understand it.

 

[Raza]

When we drop something to Earth from a reasonable height, it falls to the Earth in a straight line. If we however were to stand and throw a ball at a certain angle, it will fall to the Earth along a curved path. If it were possible for us to throw it hard enough, the ball will follow a curved path, but would always miss the earth, hence it would be falling to the earth, but always missing. Therefore, it is in orbit around the earth.

The same principle can be applied to the earth. It is falling towards the sun, but it moves sideways fast enough i.e enough tangential velocity to always miss the sun. Like the ball in orbit around the earth, the Earth is in orbit around the sun.

I got it!
Thanks
but something must have "pushed" the Earth in order to rotate?

 

[Ki Man]

When the solar system was formed, the dust gathered into rotating disks and the planets were formed from the dust, so the Earth was already floating when it was created, along with its 23 former brothers and sisters

 

[Raza]

If I were to create my own solar system, duplicating everything to the last atom but except, there was no "push" given to the planets, what would happen?

 

[russ_watters]

It would all collapse into the sun. However, that is a very unlikely condition to have. Zero is one number of infinite possibilities, and it is pretty much impossible to have a perfectly symmetrical, perfectly static cloud in a dynamic universe. In fact, scientists are finding that a pretty decent fraction of stars that we are able to make observations of have planets orbiting them. Given the limits of our current ability to find such planets, then, it is not a stretch to say that it is likely that most stars have systems of planets orbiting them.

 

[Cyrus]

Of course, in the Earth's rest frame, the Earth is, indeed stationary. At all times..*




*I know, it is dumb, but I couldn't resist posting it anyway..

You made the Earth and LTI system, nice.

 

[vanesch]

All things that do not have enough angular momentum (rotation, say), fall into the sun. So the only things that CAN, after a while, survive in a solar system MUST have sufficient angular momentum! Call this the "anthropic principle for planets"

 

[chemisttree]

Imagine that the Earth and sun were stationary with only the attractive force of gravity between them. They would move closer to each other unless acted on by another force and eventually collide. What other force might prevent the Earth from colliding with the sun if the Earth were stationary? Could the gravity of another body exactly balance the gravitational attraction of the Earth to the Sun? Maybe it could for a short time but that hypothetical gravitational source would also be attracted to the sun and move closer... unless some other force opposed its motion toward the earth/sun.

If the Earth were motionless, to be stable you would have to introduce a repulsive force like a coulombic force (electric charge both positive or both negative). If that were the case, I think every day would be a bad hair day!

Or you could start the Earth moving at a right angle to the sun and let centripetal force (supplied by gravity in this case) act to change the Earth's linear motion into a circular or elliptical orbit. Apparently, this is how the solar system formed. All the bits that were stationary were sucked up into the sun or flung away on wildly eccentric orbits and lost. That which remained was "selected" by speed and direction to eventually become the planet earth.

 

[tehno]

It seems like a childish question, but why does the Earth go around the sun? Why not stay in a single place?

Still childish ,but more interesting question,is why does the Earth turn around itself.Perhaps crazy ,but still correct answer is :Becouse nobody wants to put and effort and stop it (fortunately).
Hehehe.

 

[Raza]

Still childish ,but more interesting question,is why does the Earth turn around itself.Perhaps crazy ,but still correct answer is :Becouse nobody wants to put and effort and stop it (fortunately).
Hehehe.

I was just going to ask that.

 

[disregardthat]

What I'd like to know is if the Earth ever will bash into the sun. Or will it's orbit continue forever, taking out that the sun will collapse someday.

I have heard that in space there is not entirely vacuum, so after extremely long time, these atoms would stop the Earth enough to make it go swoop into the sun? Or would it's kinetical energy be empty someday so it would fall into the sun.

 

[pivoxa15]

I was just going to ask that.

I guess that the Earth spins because it was spinning when it was formed. There isn't much friction in space so the conservation law demands that it will keep on spinning. There is very low probability for planets to form with all motion cancelling each other in the beginning. There could be other factors for why planets usually spin.

 

[Raza]

If I were to create my own solar system, duplicating everything to the last atom but except, there was no "push" given to the planets, what would happen?

It would all collapse into the sun.

I know I am going too in-depth in this, but how does the Earth going around decreases the gravity force in such a way that makes the Earth not move closer to the sun and not go further away from the sun?

 

[russ_watters]

Still childish ,but more interesting question,is why does the Earth turn around itself.Perhaps crazy ,but still correct answer is :Becouse nobody wants to put and effort and stop it (fortunately).
Hehehe.

The Earth rotates for the same reason it revolves - it formed from a rotating cloud of gas and dust.

I know I am going too in-depth in this, but how does the Earth going around decreases the gravity force in such a way that makes the Earth not move closer to the sun and not go further away from the sun?

Huh? The Earth's motion doesn't decrease the gravitational force. The Earth is accelerating toward the sun at exactly the same rate as if it were not in orbit. It's just that since it has a component of motion perpendicular to the sun, that acceleration just pulls the Earth around in a circle (instead of letting it fly off at a tangent).

 

[Raza]

Oh, I get it, Russ Watters, thank you and thank you all for making me understand a little bit about Astrophysics.

 

[heusdens]

It seems like a childish question, but why does the Earth go around the sun? Why not stay in a single place?

This may seem like a childish reply, but how do you conclude it revolves around the sun?

We only see the sun coming up in the east and go down in the west, and they may mean the sun revolves around the earth, or the Earth evoles around it's own axis.

 

[complexPHILOSOPHY]

The Earth is flat and you will fall off it's edge if you venture to far out into the ocean! BEWARE!

 

[russ_watters]

This may seem like a childish reply, but how do you conclude it revolves around the sun?

We only see the sun coming up in the east and go down in the west, and they may mean the sun revolves around the earth, or the Earth evoles around it's own axis.

Those other things would also require the stars to be orbiting the earth...

 

[pivoxa15]

This may seem like a childish reply, but how do you conclude it revolves around the sun?

We only see the sun coming up in the east and go down in the west, and they may mean the sun revolves around the earth, or the Earth evoles around it's own axis.

If you don't know anything about astronomy than you could determine it by deduction from the experimentally verified gravitational law. Although you first have to accept that the sun is much heavier than the earth.

If you want to get into astronomy than assume the sun is in the centre than you will find other planets orbiting us also orbit in epicycles. No current physical law is able to explain this. On the other hand if you assume all the planets orbited around the sun than you will find a nice simple model with 3 laws which will explain the behaviour of the whole solar system. This reason is enough to convice that the Earth is not the centre.

 

[vanesch]

What I'd like to know is if the Earth ever will bash into the sun. Or will it's orbit continue forever, taking out that the sun will collapse someday.

Nobody knows! Of course, to the simple problem of JUST the Earth around the sun, we know that the solution is stable: the Earth would VERY VERY slowly spin into the sun (due to emission of gravitational waves) ; however, this is such a tiny effect that it is negligible on the scale of some tens of billions of years.

But with the other planets around, nobody knows. We don't know if the system is stable on very long durations. We have good indications that it is, given that it lasts already for a few billion years. But nobody knows whether or not at ridiculously long periods, the Earth cannot get "gravitationally ejected" from the solar system. It probably won't be a worry before the sun becomes a red giant.

Finally, there are extra-solar bodies which might perturb the Earth's orbit. This is unpredictable, as we don't know which bodies, and when, and how.

 

[tehno]

Apparently, Moon slowly drifts away from Earth on average.At least, I've heard/read so.Big Oceans effect?Apparently.