# What would happen to earth when a planet passes by, almost hitting earth?

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joniah2884posted 7 years ago

What would happen to earth when a planet passes by, almost hitting earth?

hypothetically speaking, if there was a planet, twice the size of earth, that would pass by earth, almost hitting us, would there be any dramatic change to the earths magnetic field? would there be any change with gravity? would Einstein's theory about polar change in the future be plausible?

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melporposted 7 years ago

Depending on the distant between the two planets most likely Earth and the other planet would collide with each other. It also depends on the planet's trajectory, the speed of the fly-by and the size of planet. These factors also would determine if the planet would swing by Earth and keep moving in a different path or collide with it. Gravity will change if both planets are pulverized to smaller pieces. As far as polar changes go that would happen if the resultant collision causes a change in the orientation of Earth's spin then the new axis orientation would become the new polar position. Einstein's theory has nothing to do with polar changes the way I understand it.

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joniah2884posted 7 years agoin reply to this

that's when there is a collision, right? how about if the planet is passing by, barely hitting earth?

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lone77starposted 7 years ago

As Melpor said, trajectory would be critical, but he misses the point of your question. You said "almost hitting." So, there would not be a collision.

Depending on the trajectory, the Earth, if it survived, would likely be moved to an elliptical or hyperbolic orbit. Hyperbolic means ejected from the Solar system.

But more important effect is the gravitational disruption of Earth. Depending on the density of the other planet and the exact distance of its closest approach, Earth may be tidally ripped apart -- if it comes within the Roche's limit of the other planet. Likewise, that other planet could suffer the same effect.

I'm not sure what the magnetic field effect would be. Magnetic field of the Earth is determined by flow within the core, but also the rotation of the planet.

Einstein never had a theory of polar change, but he did find favor with Charles Hapgood's theory of crustal displacement. In fact, Einstein wrote the foreword to Hapgood's 1958 book. If such crustal displacement is possible, then such a strong gravitational disturbance could initiate such a shift. But I'd be more concerned with the tidal effects of a near pass. If we weren't within Roche's limit, we'd have massive earthquakes, volcanic eruptions and tidal waves. Goodbye civilization!

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