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If we took material like rock from space and got it back to Earth enough times, would Earth grow as a planet?
(sh.itjust.works)
As the title says. I'm actually thinking about this hard with my friends because everything that's produced on Earth stays on Earth so it doesn't change size, but what if it's not from Earth but it stays on Earth?
This happens naturally in the form of meteors streaking through the sky. Each one of those is adding a tiny amount of mass to the planet.
But you've got me wondering about something now. When a large asteroid hits the planet, it obviously adds its own mass, but it also kicks up a lot of debris into space. Some percentage of that will reach orbital escape velocity and never come back. But I honestly don't know if there is a net mass increase or decrease after such an event? We're generally concerned about other more pressing matters in such a scenario!
unless the meteor is a rogue moon, the mass gained/lost is negligible compared to other particles interacting with the atmosphere or radiating (in and out), processes which are constantly happening.
for example, just the sun contributes some 200 tons every year (We also radiate out about the same mass that comes in). in 7.5 million years, that equals the asteroid that killed the dinossaurs (an event which happens way less often). So yeah, maybe the mass changes for a while, but even then, the dinossaur-killing asteroid is 0.000000000001% of earth's mass... If we had one meteor like that everyday for a billion years, we would get some 20% extra mass.
(rough numbers I calculated just know, double check please)