Home Discussion Forum where does earth get its energy to keep revolving around the sun?

# where does earth get its energy to keep revolving around the sun?

we know that earth revolves around the sun due to sun’s gravitational force. if earth has to resist this pull, then it should have enough linear velocity. Just like a stone attached to a string at one end and rotating the string at the other end in your hand. Also the linear velocity of the earth should be good enough to keep it in its orbit around the sun and not crash into the sun.But where from does earth gets its energy for this linear velocity to keep it going around the sun for the past million years?

1. There is no energy expenditure needed to stay in orbit. Space is frictionless. Earth’s orbital energy is constant, apart from tiny perturbations from other planets.

2. There is no energy involved in this process.It is all about the gravitational attraction between the sun and the earth.

3. A similar question answered in this website forum. Hope it helps. Quotes:
Originally Posted by AveekB
A large, very large body like earth exerts a gravitational force on moon or a smaller object and there is displacement (neglect displacement of earth). Thus work is done. So where does the energy come from to do this work?
Be a little careful here. For a circular orbit there is no work done since the force is always perpendicular to the displacement. Work is only done when the force has a component parallel to the displacement. A better example is a comet where the orbit is highly elliptical.
The comet starts far away and falls closer to the sun, work is done, the gravitational potential energy is reduced and the kinetic energy is increased. The reverse happens as the comet goes out away from the sun.

4. Solar system was formed from remnants of some supernova explosion.
Something had imparted a spin to the solar system when it was forming, so when the gases collapsed to form the sun and planets, they were all rotating and revolving.
Things that were revolving fast enough managed to stay in orbit, the slow ones collapsed onto the stable ones.
There is no source of energy now, and things have just kept going on as they were since the beginning.
It’s more there’s nothing stopping it, so it’s spinning. In day to day life friction reduces energy of spinning objects, so they stop. Here there’s no dissipation.

5. It doesn’t need energy to keep moving. ‘Cause it doesn’t have friction in its orbit. So, why would it need extra energy?

6. what has happen is, when our galaxy was created by the collision of other items in space, our planet was propelled into space and probably collided with other items the same size or bigger, merging into a larger form and all the time being propelled by these collision until the earth slowed down and was drawn to a larger item putting the earth into an orbit.
the earth got its original energy from the impact of the big bang theory or the theory of how the universe was created. that is to say, there was a large explosion that caused items to be propelled into space, and collide with each other forming larger items.

7. Earth is in motion, traveling through space with the sun’s gravity tugging us along. Earth passes the sun, slows down a little and gets tugged back behind the sun and around to the other side where we speed up as we get closer and pass again. The distance traveled by the sun in a year is about 46 astronomical units (AU). Relative to the sun our orbit is an ellipse, but our path through space is actually sinusoidal (a sine wave), closer in January and most distant in July. It doesn’t require energy to remain in this orbit. It is equilibrium of mass, gravitational attraction, and inertial force.

8. At the time of formation every such body gets some initial momentum. Distribution of such momentum is absolutely random. So Earth started off with some momentum (linear) implying some velocity. The other thing is the gravitational pull of Sun.
As it falls towards the Sun, its velocity takes it past it. The velocity gets slowed down again under the (gravitational) pull. So we have two energies, Kinetic Energy (KE = mv^2/2) due to the Earth’s own velocity. The other one is the gravitational Potential Energy (PE = Gm1 m2 /distance) exerting the pull. Averaged over one orbital period the total energy is conserved
E = KE + PE
as their no frictional force to retard it, like in the case on Earth where we are unable to (conditioned to) think of a situation without the velocity slowing down to zero as we encounter friction.
When Earth approaches closest to Sun its KE, tangential to the Sun is maximum. But whatever velocity is there, directed tangential to the Sun carries it away.
The interaction is cyclic and has a periodicity that is the time for one orbit to complete.Always there is an interaction leading to exchange between the radial component of Earth’s velocity (directed towards the Sun) and the gravity of Sun. If both forms of energy equal exactly, then velocity is uniform and there is no incentive for velocity to increase and remain in a circular orbit. Always there is a difference between the two to keep the orbit as non-circular and elliptical as possible. Even the so-called circular orbit is slightly elliptical as you can’t prove that the orbital eccentricity is absolute zero (e = 0 .0000. . . …0 . 0) so as to be circular.
In the relativity ‘model’ of the stretched rubber sheet with Sun’s gravity creating a depression; if Earth is represented as a spherical ‘marble’ it can be visualised. As the marble is most probable to have some momentum (mass X velocity) it goes near the hollow and shoots past. If it can be set into motion to execute a periodic motion, it climbs up from the hollow and then falls back and climbs up again, always missing falling into the hollow head-on. If the rubber sheet has zero friction the marble keeps executing its ‘orbial’ motion forever, like in space. Also, probability of the marble having zero tangential velocity is zero, however much be the precision you employ to launch it.
In the event of the marble getting captured (like in a black-hole), its tangential velocity (feeble to counter the massive gravity or deeper depression) makes it spiral down, executing helical motion.

9. The earth is a ball and it spins. Wow! It’s kind of like something that just happens. Do you understand?

7

21

6

7

3