When planets form, it's usually from impacts of material that increase their mass. For rocky worlds, it's thought that the a majority of their 'spin' is the sum of rotational momentum imparted on them from impacting objects... Take Earth, for example - our rotation occurs once every 23 hours and 56 minutes, and our axis is off-set from the plane of our orbit by about 23.5 degrees. It's thought that a Mars-sized object (called Theia) slammed into the early Earth, blasting off tons of mass into orbit that collected to form the moon, and gave us a very quick rotation as well as our 23.5 degree offset.... Over time, our day has lengthened to the near-24 hours we know now.
The gas giants, on the other hand, spin much faster. Jupiter's day is less than 10 hours; and, it's thought that as they formed, their rotation was much slower, and their 'surface' was much larger and diffuse. Over time, their increasing gravity drew in the gaseous material surrounding them - and, like an ice skater pulling in her arms during a spin, their rotation increased - to the speeds we see today.
Conservation of momentum. Eventually all the planets will have one face to the sun permanently , they will become tidally locked. Even then they will continue to rotate once in a revolution around the sun.
why wouldn't they? any force in a given direction on them would make them spin, especially in a frictionless environment of space. A meteor collision would be enough to get it spinning
And since everything in our solar system was formed from that same disk, its momentum sent nearly everything spinning in the same direction. (Notable exceptions include Uranus and Venus, whose odd spins probably stem from subsequent collisions with asteroids.) Our planets have continued spinning because of inertia.27 Aug 2015
Answers & Comments
Verified answer
When planets form, it's usually from impacts of material that increase their mass. For rocky worlds, it's thought that the a majority of their 'spin' is the sum of rotational momentum imparted on them from impacting objects... Take Earth, for example - our rotation occurs once every 23 hours and 56 minutes, and our axis is off-set from the plane of our orbit by about 23.5 degrees. It's thought that a Mars-sized object (called Theia) slammed into the early Earth, blasting off tons of mass into orbit that collected to form the moon, and gave us a very quick rotation as well as our 23.5 degree offset.... Over time, our day has lengthened to the near-24 hours we know now.
The gas giants, on the other hand, spin much faster. Jupiter's day is less than 10 hours; and, it's thought that as they formed, their rotation was much slower, and their 'surface' was much larger and diffuse. Over time, their increasing gravity drew in the gaseous material surrounding them - and, like an ice skater pulling in her arms during a spin, their rotation increased - to the speeds we see today.
Conservation of momentum. Eventually all the planets will have one face to the sun permanently , they will become tidally locked. Even then they will continue to rotate once in a revolution around the sun.
why wouldn't they? any force in a given direction on them would make them spin, especially in a frictionless environment of space. A meteor collision would be enough to get it spinning
Because round is the only possible way to spin.
The Conservation of momentum left over from the Solar System's formation.
It like has to do with inertia and gravity and sh!t.
And since everything in our solar system was formed from that same disk, its momentum sent nearly everything spinning in the same direction. (Notable exceptions include Uranus and Venus, whose odd spins probably stem from subsequent collisions with asteroids.) Our planets have continued spinning because of inertia.27 Aug 2015
Because physics.