The effect of Faraday braking on the Earth’s orbit

[jeffkosmo]

TL;DR

See below.

If you let a magnet free-fall down a copper or aluminum tube, the induced magnetic field in the surrounding conductive medium imposes a braking effect on the magnet, reducing its speed (explained by Lenz’s law).

The earth, being a large magnet, is essentially free-falling around the sun. The sun is continually ejecting plasma into the solar system. The plasma is conductive.

Shouldn’t this impose a braking force on the earth, causing it to fall ever closer to the sun?

 

[Vanadium 50]

The sun is continually ejecting plasma into the solar system. The plasma is conductive.

Have you compared the conductivity of this plasma with copper? If not, maybe you should.

 

[snorkack]

Earth is subject to a number of tiny decelerating and accelerating forces:

1. Earth orbiting Sun should due to general relativity emit gravitational waves. Therefore Earth should experience a force of gravitational wave resistance
2. Sun rotates faster than Earth orbits (Earth orbits in 365 days, Sun rotates in 25 days). Earth should raise a tidal wave in Sun. Rotation of Sun should cause tidal drag in gaseous body of Sun, which should slow down Sun rotation and speed up Earth revolution, propelling Earth to a higher orbit
3. Earth also rotates faster than Earth orbits. Sun raises tides in Earth oceans slowing down Earth rotation. But excluding all other forces, the combined angular momentum of Earth rotation and Earth revolution should be constant - therefore tidal friction should have not only a torque on Earth rotation but a propulsive force on Earth revolution.
4. Even if solar wind were not plasma and were completely neutral atoms that pass unobstructed through Earth magnetic field, or if Earth had no magnetic field like Venus, or had a magnetic reversal and no field for a time, the solar wind particles would still collide with body and atmosphere of Earth and exert some wind drag. Due to Earth revolution, the solar wind drag should have a tangential component contrary to revolution.
5. When Earth does have a magnetic field (like now and most of the past), the magnetic field increases solar wind resistance.

So can anyone offer numeric estimates of the enumerated small drag components?

 

[Vanadium 50]

So can anyone offer numeric estimates of the enumerated small drag components?

Have you compared the conductivity of this plasma with copper? If not, maybe you should.

 

[alantheastronomer]

Interesting concept - the solar wind is a perfectly conducting plasma, much more so than copper, so it should be a significant effect - in principle. In fact, it's what's thought to govern the accretion of matter onto stars and is called the magnetorotational instability, or Balbus-Hawley accretion. For the solar wind to have an appreciable influence on Earth's orbit however, it would need to be much more massive than it is.

 

[alantheastronomer]

@jeffkosmo if you're still curious, you can estimate the effect the solar wind might have on the Earth's orbit. Find out the charge density and velocity of the solar wind and calculate the force this exerts on Earth's magnetic field and how much this would change Earth's velocity in it's orbit around the Sun after 4.5 billion years.