curiousmind111 t1_j3vd1my wrote
Reply to comment by Delamoor in TIL Pluto hasn't completed an orbit around the sun since its discovery. Pluto's orbit takes about 248 years, and Pluto was discovered in 1930. by irbinator
Interesting.
But what if we had no moon, and we didn’t spin - from the start. We just always had the same side facing the sun. That would have nothing to do with moons or tides. That’s why I was surprised to hear “tidal” in the comment. But. Googled and that’s what they call it.
Even stranger when there’s no water on the planet.
Delamoor t1_j3vswa0 wrote
Interestingly, that wouldn't be physically possible.
The process of accretion in zero gee creates angular momentum by its nature: stuff slams into other stuff and that kinetic energy has to go somewhere, and it can't go any further towards or back away from the centre of gravity... so it goes sideways and turns into a spin.
That's why neutron stars generally rotate near the speed of light; all that matter came inwards with the force of a supernova, so supercharged the spin. Also why black holes spin and accretion disk form. You basically can't have a body of matter coalesce in space without it starting to spin at least a bit. Well, unless you're physically there to carefully place the matter bit by bit with near zero kinetic force, anyway.
If we had no moon then there would be no signficant drag (though there would still be a tiny, tiny, tiny bit from the sun and other bodies in the solar system, but barely noticeable even in astronomical timescales), and we would for all intent and purposes basically never stop or slow our spinning.
curiousmind111 t1_j3yhf9l wrote
Nteresting. Even if we had water but no moon? I’m imaging that water adding Damone drag as we rotate. thanks for the Excellent answer!
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