Eli5 on why do planets spin?
In: 1322
Galaxies were created from matter coming from all directions which caused them to spin, this spinning matter created the stars and planets. Spinning matter—>spinning planets
Really big objects like planets are squishy when they collide with other planet size objects.
If two planets of the same size going the same speed hit head on, they would stop moving. This is because “forces” cancel out.
If these two objects hit off center, up/down/left/right, some of their energy becomes “spin” energy. If you’ve ever pushed on the side of a swivel chair you have seen this.
If one of the planets has more “momentum” because it is heavier or faster or some combination, the new “clump planet” will move in the direction of the planet with more momentum, just slower.
If the planets hit at an angle, like if one object was going north east and another north west, they would then move north, depending on which was faster/heavier.
Because it is more likely that they will spin than they won’t spin. That’s it, just statistics.
Think of pouring milk into coffee, it makes those swirl patterns. Is it possible that you could pour the milk in perfectly straight so that every molecule of milk hits every molecule of coffee perfectly dead-on? I guess. But it’s WAY more likely that milk molecules will hit coffee molecules off-center, with like a glancing blow, causing them to spin.
[removed]
It’s leftover energy from when it was formed. A basic practical demonstration you can do in a spinning desk chair is to hold your arms straight out, preferably with something heavy in your hands like a big book or even a dumbbell. Start spinning. Then bring your arms in so your hands and whatever they’re holding are against your chest You should notice you spin faster now. Stretch your arms back out and you slow down again. Play around with this for a bit.
Now planets are formed from random bits of space debris in a big solar system sized cloud that collapsed under gravity. If there was any spin at all before gravity pulled it all together, that spin will be magnified as it collapses and shrinks. The effect is much greater because of the vast distances involved here, where debris from millions of miles around collapses down to something just a few thousand miles in size.
When planets are formed, it is usually due to a collision. When that happens, you have centripetal force as the two or more bodies start to form into a planet. Newton’s first law states that bodies in motion will stay in motion unless acted on by an external force. So these newly formed planets will keep their inertia, in the form of angular momentum, and because space is a vacuum, the planets will keep spinning because there is no friction to stop them. They don’t move in a straight line as the law states because they are bound by gravity.
If a planet is formed by other means, and still spins- then that planet was likely struck by an asteroid, comet, or some other body that imparted its momentum, making the planet spin.
Mercury doesn’t spin. Neither does the moon.
I don’t know why. And I’m too lazy to look it up. I’ll come back after my nap, and hope someone replied with an explanation.
Because there’s only one way to be still and a billion ways to spin. So the chance of not spinning is 1 out of billions. So everything in the universe spins.
Quick Answer: It would be harder for them NOT to, if you think about it. Picture all those videos of astronauts letting go of an object while in a space station and the thing sloowly drifts and tumbles. Imagine how hard it would be to keep an object perfectly still from letting it go.
Longer Answer: When a cloud of objects gets accelerated in toward a central source of attraction, it tends to swirl as it moves to the center, like the water getting sucked toward a drain does. And the solar system was first formed like that – a bunch of gasses got close enough for their gravity to start “clumping” them together toward the center. As they do that, the cloud starts to spin. Then later that cloud of matter starts to clump tighter and tighter, forming a few solid lumps as the matter gets compressed tightly enough. The big one at the center becomes the sun and the littler ones around it become planets, but because the cloud they were formed from was already swirling around the center to begin with, when it compressed down into a solid ball, that ball already had quite a bit of spin momentum. This is also why the planets all spin the same direction – except for two
And those two exceptions, Venus and Uranus (Venus spins backward compared to the rest, and Uranus spins “sideways” compared to the rest, are immensely interesting because of it.) There hasn’t been a definitive answer yet for how they got that way. One possibility is that Venus might be the result of a massive impact between two planets like what happened to the Earth that created the Moon, if the impact was just right it could flip the planet upside down causing the spin to flip. Another possibility is “foreign object capture” where maybe Venus wasn’t originally part of the solar system but was an external planet that flew by and got captured by the Sun.
Can someone r/explainlikeicaveman this? Most replies words too big 😅
Latest Answers