system
Given the following post, respond as if you're commenting on Reddit:
human
If earth was on a collision course with a planet 2x our size, would we (our bodies) get sucked up and get hurled towards the other planet due to it's gravitational pull as the planets got closer?

What if the other planet was the exact same size as earth? Would we be off the ground but in suspension (floating) at some point?
gpt
The key thing here isn't the total gravity of the planet, but the *tidal force* - that is, the *gradient* of gravity. Basically, the planet is pulling the Earth and you by about the same amount. So if the planet's gravity is stronger than the Earth's gravity, that just means that the whole Earth - you included - is accelerating towards the planet more than the planet is accelerating towards the Earth.

However, the force on the Earth and the force on a dude on the surface is only *about* the same. Gravity drops off with distance, so if you're on the near side of the Earth, then you feel slightly more gravity than the Earth does. So you will get pulled up. However, to actually get pulled off the Earth, this *difference* in gravity needs to be stronger than the *total* gravitational force that the Earth is pulling you with. This means that the planet would need to be extremely massive - really, something like a black hole - and not simply double the mass of the Earth. Then you could get people ripped off the surface of the Earth - and probably the Earth getting ripped apart too.

Alternately, if the planet was *really* close - like touching the Earth - then yes, at that point the gravity on the surface would cancel out. But that's like a single instant before the planets smash into each other.