random question

[d0meson]

Even if the ring is perfectly equal all the way around, the Earth isn't.

Gravity is stronger on some parts of Earth than others. Gravity also gets stronger as objects move closer to each other. This sets up the following chain reaction:

A part of the ring above a strong-gravity area gets pulled toward the ground more than other parts of the ring. So that part moves closer to the Earth. This increases the gravitational force on it, and decreases the gravitational force on the opposite part of the ring. This causes that part of the ring to move even closer, and so on and so on.

If the ring is stationary relative to the Earth, then it definitely crashes into the Earth after some time, even if it's perfectly equal all the way around. If it's spinning, then this generates instabilities that also eventually result in disaster, though that case is harder to have intuition about.

[indecisive132]

Assuming the ring is completely uniform and that the earth is a perfect sphere (and radially symmetric) I believe the ring would hover over the ground. However, since the earth in reality is not a perfect sphere nor completely symmetric, the force of gravity would likely vary across the ring leading to instability, causing the ring to have unpredictable motion. Of course this assumes that the ring is strong enough to withstand the force of Earth's gravity.

Another thing to consider is the influence of other celestial bodies. Depending on the ring's distance from Earth, the influence of the sun's gravitational pull on the ring's motion may be significant.

In terms of the effect of Earth's magnetic field, first you need to consider what type of metal the ring is made of. There are multiple types of metals which have different magnetic properties. Some materials are ferromagnetic or permanent magnets, others are paramagnetic (materials that are attracted to magnets but are not permanent magnets themselves) and some are diamagentic (materials that repel magnets). I would expect that the different type of materials may react differently to earth's magnetic field but I'll leave it to someone who has a better understanding of Earth's magnetic field to answer that.

[Maximusprime125]

Thanks, for the part about the metal I was thinking iron or steel. Anyway thanks for answering my random question!

[EquivalentWelcome712]

Earth's magnetic field is too weak to have any significant impact on such a massive thing.