Eli5 on why do planets spin?
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Have you ever played billiards? Unless you hit a ball perfectly dead in the center it’ll have “English,” or spin. This is because the force from the cue ball or cue stick goes through and around the other ball’s center of gravity. If it goes dead center there’s nothing for the force to go around so the ball will slide straight instead of rolling or spinning.
All the rocks and asteroids and things in space have a LOOOONNNG time to hit each other imperfectly and off center, so they spin. Planets are just big collections of lots of space rocks (or gasses), but the forces are the same. They’ve had long enough that they bump each other enough to self-organize into the same plane with the same spin.
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