2006-11-21 15:54:51 · 9 answers · asked by Anonymous in Science & Mathematics ➔ Astronomy & Space
There is no force that causes the planets to rotate. Most of the rotation comes about from the conservation of angular momentum. Angular momentum is given by L=m*w*r2 where m is the mass, w is the angular velocity in radians per second, and r is the radius of the circular motion. Due to conservation of angular momentum, if the radius of the orbit decreases, then its angular velocity must increase (as the mass is constant).
All planetary and stellar systems are born from the collapse of dense interstellar clouds. The clouds may originally be very large (even thousands of light years across). Consider a portion of the cloud the collapses from a size of a light year or so to the size of the solar system. That is a huge change in the size of the system. So, the very slight rotation that the cloud has in the beginning is increased dramatically when the collapse takes place. In fact, this is one of the barriers in star formation: there is excess angular momentum and there has to be a way of losing angular momentum before you can form a star.
Anyway, the bottom line is that stars like the Sun spin from the original angular momentum that was there in the solar nebula from which it formed. Not only that, all orbital motion of the planets (including the spin) is due to this orginal angular momentum.
You are saying that original angular momentum of the cloud causes orbital motions and rotations of the planets(mostly). But in the case of orbital motions we have gravitational force that gives us some restrictions of movement(Kepler laws,for example).
What I am saying is that there will be no planets if there was no initial angular momentum in the primordial solar nebula. If a nebula with absolutely no rotation collapses, then there will only be a central non-rotating star and there will not be any planets. Planets form out of a protostellar disk, which itself forms only because of the initial angular momentum of the cloud. The dynamics of a rotating body is of course controlled by forces like gravity. Kepler's laws are a direct consequence of gravity.
All the planets in our solar system spin.
2006-11-21 23:11:17 · answer #1 · answered by Sporadic 3 · 1⤊ 0⤋
Spin is a function of the vectors present when a planet is formed. Most planets were formed from material that was in orbit around the Sun. As this material joined together, the total momentum was added to the total spin of the planet. This creates the usual spin that is observed in which the spin is perpendicular to the plane of the ecliptic.
Eccentricities to the norm are cause by the impact upon the planet of objects with enough momentum to change the angle of spin, such as when the Earth was hit by a large object which caused the ejection of material which became the moon, and knocked the Earth's spin off by about 23 degrees.
Something very large must have hit Uranus to knock it over about 90 degrees.
Most astronomers say the Venus is spinning in a retrograde direction. How this can be true is not understood. In my opinion, it was simply hit by something that knocked it over 180 degrees. Maybe Mercury was involved somehow!
All the planets spin. If they are near another large gravity field, they often tune the rate of spin so that one face always faces toward the larger mass. This is what both the Moon and Mercury do.
;-D Please don't tell me that the Moon is not a planet. That is not the point in this discussion.
2006-11-21 16:21:59 · answer #2 · answered by China Jon 6 · 0⤊ 0⤋
All the planets spin, all the moons spin. However, some are locked by gravity gradient to the object they orbit, and their orbital period match the spin period, like our moon for instance, which shows always the same hemisphere to us; its spin is the same duration as its orbit.
The reason this synchronous orbit occur is that it is a stable arrangement. Over billions of years, most planet would have slowed down to synchronous orbits. There will still be a spin, but a much slower one.
2006-11-21 16:11:17 · answer #3 · answered by Vincent G 7 · 0⤊ 0⤋
All planets interior the image voltaic gadget spin on their axis. while the image voltaic gadget first formed, each and all of the venture that created the planets substitute into spinning. each and all of the planets different than Venus spin counter clockwise. Venus spins clock clever. The planets do take distinctive quantities of time to spin as quickly as around. Mercury and Venus take the longest, at the same time as Jupiter spins the quickest at below 10 hours to thoroughly spin as quickly as.
2016-11-26 00:15:55 · answer #4 · answered by horabik 3 · 0⤊ 0⤋
All the planets in our solar system spin (..rotate on their axes). So does our sun. The reason is that they were all formed within a vast cloud of gas and dust that contained motions of its own. Each of the planets and our sun took on some of this motion. It continues today.
2006-11-21 16:00:00 · answer #5 · answered by Chug-a-Lug 7 · 1⤊ 0⤋
every planet and satellites spins.. also sun spins on axis.. its due to that motion when the hot spinning cloud blasts in space.. the middle of that cloud is Sun and the particles are planes and satellites.
2006-11-21 16:03:49 · answer #6 · answered by Nishu 2 · 0⤊ 0⤋
They all spin ... at different rates. Every planet in our solar system has a "day" that isn't too far off of our own.
2006-11-21 16:10:45 · answer #7 · answered by Anonymous · 0⤊ 0⤋
It is a natural stabilizing effect -- deep physics, lots of numbers involved but very common in our universe.
2006-11-21 16:04:13 · answer #8 · answered by Anonymous · 0⤊ 0⤋
Because of the gravity that is pulling towards the sun
2006-11-21 17:04:22 · answer #9 · answered by darthchris316 3 · 0⤊ 1⤋