Magnetic Field Strengths of Planets

The conventional view of planetary magnetic fields is that they are the result of liquid metallic currents that move like dynamos deep inside the cores of planets.

The liquid metallic currents are driven by internal mechanisms that can only be inferred from their resulting magnetic fields.

Predictive vs non-predictive theories

This is an example of a non-predictive theory where only invisible and hypothetical inferences are possible. Nothing visible or directly measurable can be inferred. The truth of the theory cannot be determined. It rests fully on trust in the original hypothesis.

In contrast we have the theory supported in my book where we can infer planetary magnetic fields by observing the atmospheres, wind speeds and rotation speeds of planets.

The thickness and the overall rotational speed of a planet's atmosphere tells us roughly how strong the planet's magnetic field is. Our theory is therefore predictive and testable. All we need to do in order to give an estimate of a planet's magnetic field is to observe its visible characteristics.

Hollow or liquid core

We know from measurements on Earth that planetary magnetic fields appear to come from deep down. However, this doesn't mean that this must be the source of it. It merely means that our planet needs to have a fluid core capable of generating a magnetic field in harmony with external forces applied to it from the above atmosphere.

The core can be a metallic liquid, or it can be a plasma filled hollow. As long as it is something that responds harmonically to external magnetic inputs, we're fine.

Plasma currents

The central idea in our theory is that the magnetic fields of planets are created by charged gases in motion, aka plasma currents. Since it's well established that all atmospheres are charged, especially at high altitudes, we can say that all planets with an atmosphere have plasma currents moving around them.

The jet stream and Earth's magnetic field

High altitude winds are visible example of plasma currents. We cannot see the charges moving about, but we know that they are there, and we know that they generate magnetic fields when they move.

The plasma currents are in turn driven externally by the Birkeland currents that also produce the auroras at the poles. Everything is in the end connected to the Sun and the plasma current that drives the entire solar system.

Testing our theory

With this in mind, we can go on to match observations with facts to see if we can indeed predict a planet's magnetic field strength by simple observations:

• Mercury has no atmosphere, and presumably a small and inactive hollow. This explains why Mercury has a very weak magnetic field.
• Venus has a thick atmosphere that moves at high speeds. But the planet is rotating very slowly, so there's little contribution to the overall speed form the planet itself. The slow rotational speed of Venus is also an indication of little to no contribution from any internal atmosphere or liquid metallic core. This explains why Venus has a weak magnetic field despite its thick atmosphere and strong winds.
• Earth rotates a good deal faster than Venus, and it has a jet stream and an active internal current. This explains why Earth has the strongest magnetic field in the inner solar system.
• Mars is similar to Mercury, but less extreme. It has a thin atmosphere and probably a slightly larger hollow. This explains why Mars has a magnetic field that's stronger than Mercury's but weaker than Earth's.
• Jupiter is spinning very fast on its axis, and it has a thick atmosphere. Its large and diffuse core is likely to be very active. It's therefore no surprise to learn that Jupiter has the strongest magnetic field of all planets in the solar system.
• Saturn is similar to Jupiter, but with a thinner atmosphere and slower spin. Its magnetic field comes in as the second strongest in the solar system.
• Uranus has more than two poles, indicating that there's a mismatch between the internal plasma current and the external current. The strength of its magnetic fields are less than Saturn.
• Neptune is similar to Uranus, and has for this reason magnetic fields similar to it.

Conclusion

The plasma model for planetary magnetic fields can be used to make predictions related to the strength of magnetic fields. This is unlike the dynamo hypothesis which can only be used retrospectively. The dynamo can only be inferred from measurements of the magnetic field. It cannot be used to predict anything, and is therefore useless as a predictive model.

The fact that the plasma model gives us correct predictions based on observations of atmospheres, wind speeds and rotation speeds of planets, makes it the better model in terms of usefulness.