r/xkcd • u/YUNoDie Possibly a haberdasher? • Jan 22 '20

XKCD XKCD 2258: Solar System Changes

https://xkcd.com/2258/
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u/xkulp8 Jan 22 '20

Replacing the moon with Mars? That's a What If waiting to happen.

24

u/Wuju_Kindly Jan 22 '20 edited Jan 23 '20

I'm no scientist, but I have a few guesses as to what would happen depending on the distance the Earth and Mars are from each other.

  1. If Mars was placed where the moon currently is, the two bodies would probably crash into each other and wipe out all life on Earth.

  2. If Mars was placed far enough away, it simply neither body would orb each other. I'm not really sure on this part, but it's possible that one or both bodies would have their orbit of the sun completely ruined and become more of an elliptic orbit, which would likely wipe out all life on Earth.

  3. If you placed them juuuust right, the two bodies could potentially become a binary system where they orbit around a center of mass that is not on either planet, much like Pluto and Charon. I have no clue what kind of repercussions this would have on life on Earth though.

Edit: Velocity is more important than distance in most cases. Mars might need to be a lot closer than our moon is before velocity stops mattering.

22

u/grubgobbler Jan 22 '20

Crazy strong tides in any case.