# Does the Moon's magnetic field affect Earth's magnetic field?

I wanted to ask a question; it's simple but I cannot find any possible and perfect solution.

Earth has poles, North and South. By which we can get directions using a compass or a needle compass, but that's not the concern.

My Question:

Would the Moon cause a change in the magnetic field of Earth when they are interpassing or colliding with each other, as the Moon does come between the magnetic path of the Earth.

So would the Moon's magnetic field affect the Earth's magnetic field, just as its gravitational pull affects Earth's gravitational pull for oceans?

So would the Moon's magnetic field affect the Earth's magnetic field, just as its gravitational pull affects Earth's gravitational pull for oceans?

Yes, but only slightly. Firstly, magnetic fields can superimpose, so the field at any point is the sum of the field due to the Earth and the field due to the moon.

However, the moon is rather far away (and has a weak magnetic pole strength), so the magnetic field due to the moon on Earth's surface is nearly negligible (magnetic field also decreases as an inverse-square law)

In addition, the magnetic field of the Moon may bolster or erode the Earth's field as magnets moving relative to each other tend to either lose magnetization or become stronger. But this process has a negligible effect when we take the Moon and Earth.

• How does the moon even have a magnetic field? I thought you had to have a churning liquid core for that? Commented Nov 7, 2014 at 23:32
• @Scottie the moon does have a molten core, though it is not rotating anymore IIRC. However, it rotated in the past magnetizing the crust. Commented Nov 8, 2014 at 7:31
• Dipole fields do not decrease as an inverse square law. The decrease will be steeper than $r^{-2}$. Commented May 16, 2015 at 15:37
• Specifically, it goes as r^-3 Commented May 18, 2015 at 18:25
• @Manishearth Your comment - " the moon does have a molten core, though it is not rotating anymore IIRC. However, it rotated in the past, magnetizing the crust" - does that mean the moon does not have a magnetic field at present, but it had a magnetic field in the past?
– apk
Commented Jul 31, 2022 at 15:17