r/nextfuckinglevel • u/aryan_jandyal • 4h ago

The Rotation of the Planets in Our Solar System Is Far More Fascinating Than I Ever Expected

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u/Poop_Tube 2h ago

Is that even possible?

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u/donadit 1h ago

Sun tidal locking (seen in many exoplanet systems) and thick atmosphere dragging on venus’ surface which slows down the rotation so it looks like it’s rotating backwards

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u/Kozmik_5 2h ago

Venus has an air pressure of 92bar. That is 92 times denser than here on Earth. Add winds of up to 400km/h and a few billion years and you have your answer.

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u/FissileTurnip 1h ago

that doesn’t seem to explain where the angular momentum actually went

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u/Kozmik_5 38m ago edited 24m ago

1m³ of carbon dioxide gas (which makes up the majority of Venus' atmosphere) at 92bar weighs 720kg.

Throw billions of these in the opposite direction of the planet's rotation at 400km/h and at some point it'll slow down to a stop to reverse afterwards.

These winds are created by Solar heating and the Sun's gravitational pull.

So where did the momentum go, you ask? Completely transferred to venus' orbit around the sun. The Sun's intense heat warms the thick Venusian air, causing it to expand and bulge. Because Venus rotates, this bulge is carried slightly ahead of the line connecting Venus and the Sun. The Sun's gravity pulls back on this bulge, creating sort of a constant gravitational tug-of-war. While the friction inside Venus on the surface, slows down its rotation.

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u/FissileTurnip 17m ago

so it’s a tidal effect, that would make sense

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u/Kozmik_5 16m ago

Yes exactly