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Ezekiel.
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Why do all the planets orbit in the same direction around the sun?
BobG said:Like chroot said.
When gas and dust coalesce together, the chance of them coming together precisely at the right motions to have no rotational motion is virtually nil. The dust cloud spins, flattens, and eventually clumps together in little balls. Most of the matter winds up in one big ball in the center, but all of the balls orbit and spin in the same direction the original cloud did.
Which means a tougher question would be:
What's wrong with Venus? It orbits the right direction, but it's spinning the wrong way.
What's wrong with Uranus? Why is it lying on its side?
Why does the Sun spin so slow? If almost all of the mass winds up in the middle (about 98% of the solar system's mass lies in the Sun) and the ball spins faster as the mass gets closer to the center, the Sun should be spinning really fast (it takes 27 days for the Sun to rotate).
You answer those questions and you'll be famous.
Nereid said:The first stage does rely upon 'dust' sticking together when it collides - how can this be? First, 'dust' is a little misleading, most of it is 'ices', water ice, ammonia ice, methane ice, dry ice, ... Second, a high proportion of the collisions are at very low relative speeds.
The direction of a planet's orbit is determined by the initial conditions of its formation. When a solar system forms, it begins as a swirling disk of gas and dust. As this disk collapses, it begins to rotate in a certain direction. The planets then form from this disk and inherit the direction of their parent disk's rotation, leading to all planets orbiting the sun in the same direction.
While it is possible for a planet to have a retrograde orbit (orbiting in the opposite direction), it is extremely rare. This is because the initial conditions of a solar system's formation tend to lead to all planets orbiting in the same direction. However, there are some exceptions, such as Venus and Uranus, which have retrograde rotations.
The fact that all planets orbit the sun in the same direction is evidence of the uniformity and consistency of our solar system. It also allows for the stable and predictable movement of the planets, which has been crucial for navigation and understanding our place in the universe.
No, the speed of a planet's orbit depends on its distance from the sun and its mass. The closer a planet is to the sun, the faster it will orbit. For example, Mercury orbits the sun at a speed of about 107,000 miles per hour, while Neptune orbits at a speed of about 12,000 miles per hour.
Yes, a planet's orbit can change over time due to various factors such as gravitational interactions with other planets, the sun, or passing objects. These changes can be small and gradual or more dramatic, leading to a change in the planet's orbital direction or distance from the sun.