Like on Venus which is about the same size as Earth the day is longer than the year and does every 243 days but revolves the sun every 225 days. So it rotates very slowly and 1/243 the speed of Earth. Yet Jupiter which is way bigger rotates in only about 10 hours. So why such variation and what causes it?
In: Physics
When a planet is formed their initial rotational speed is just the speed of whatever formed the planet, so it varies for every planet. Major asteroid impacts can change it.
Over time planets experience tidal locking from both the sun and any moons, this is why the moon has a day equal to a month. Basically what happens is everything causes tides (like we see in the ocean, but it’s also the rocks on the planet moving). The tides are powered by external gravity and act to match the day period with the other object. This means the moon and sun is always slowing down the earth. In general the sun is also trying to slow down planets, which is why Mercury has a day and year so close. The more the gravity is involved the stronger it is, and Mercury is very close to the sun.
Why would you think that they wouldnt?
Its ridiculous to think two planets would have even a slightly similar rotation.
Planets are like snowflakes kid. They are never going to be the same.
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