Why do all planets (except pluto) revolve on the same disc?
91267
You are referring to a concept in planetary astronomy call inclination of orbit.  The "disc" that the Earth revolves around the Sun on is called the ecliptic plane.\n\nTechnically speaking every other planet has some orbtial inclination or tilt of their disc.  But it is very small so the eight major planets are said to orbit in roughly the same plane (ecliptic).  \n\nPluto is different.  Its orbital inclination angle is about 18 degrees with respect to the ecliptic.  That's big compared to the other planets. \n\nNow the question is why are the eight major planets in the same plane?  Why is Pluto not?\n\nWhen the solar system formed it was originally a giant sphere of gas and dust and over time was gravitationally attracted into a compacted sphere.  When this happens systems need to conserve angular momentum.  This results in the sphere becoming flattened.  This flattened sphere now looks like a disc.  The disc is roughly the ecliptic plane. An analogy to this scenario is pizza dough being spun by a chef into a disc. \n\nPluto, it is believed, was probably originally part of this disc but later had an intereaction with another object which since changed its orbit.
180202
Neither. It's the mass of the planet itself. Everything that has mass projects a gravitational field. The more massive an object is, the bigger its gravitational "pull". This is why objects like the Sun can support several large planets, while Pluto (which has a moon about a third the size of it) gets pulled around by its moon.
63676
These are good questions. I do not think anyone knows exactly, but I have heard the conjecture often that Pluto is an escaped moon or a captured planet from somewhere else, and was not present at the formation of the Solar System. Also it is possible that Pluto's strange orbit is the result of some collision. \n\nThe rotational angular momentum of Uranus is quite different from the other planets. It's rotational axis is tilted significantly from the orthogonal to the ecliptic (plane of orbits of most planets), and it is said to rotate in the "opposite" sense to earth and the sun and some of the other planets. However, since the tilt of Uranus' rotational axis is roughly 97.92 degrees, I do not know how strongly I would want to assert that it rotates in the opposite or retrograde sense to most of the other bodies in the solar system. Again, this could be caused by a collision. In one of the attached references, it is claimed that this could be caused by a tidal effect, but it is hard for me to understand how. \n\nIt turns out that both Pluto and Venus also rotate in a retrograde sense, so it is not that uncommon, although theories of the origin of the solar system imply that one would not expect a lot of deviations of angular momentum from the major direction of angular momentum in the system. In the case of our system, especially given the orbits of the planets with small inclinations to the ecliptic, and the very large angular momenta of the Sun, Jupiter and Saturn, this is basically correct. \n\nNeptune is probably called the blue planet because it is blue, although of course Uranus and Earth are blue as well (for different reasons). Neptune's blue is at least partly caused by the presence of methane in its atmosphere.
562236
Its earth and venus...the reason behind it is due to their some what similar size, mass of planet, rotation and revolution time and gases in some cases. hope so u satisfied with my answer.
130418
There is really only three planets that exhibit retrograde motion; Venus, Uranus and Pluto. \n\nWhen viewed from the vantage point of the north celestial pole, the planets rotate on their axes in a counter clockwise direction, except for Venus, Uranus and Pluto, which rotate in a clockwise (i.e., retrograde) direction. \n \nIt is also interesting that the rotational axis of Uranus is roughly orthogonal to those of the other planets, almost in the plane of its orbit. \n\nInterestingly, all of the orbits of the planets are also in a counter clockwise direction, as the rotation of the sun.
347854
It's pretty arbitrary isn't it? Look down on the North pole and the earth is turning clockwise, look down on the South Pole and it's the other way around.\n\nA more interesting question is: why are (almost) all planets orbiting and rotating in the same direction?\n\nThe solar system, earth included, is supposed to have formed from a dust cloud that contracted due to gravity. This cloud rotated in a certain way. As spin has to be conserved, all bodies in the solar system rotate in the same way.
407938
It is a factor in their formation. As matter gravitationally comes in proximity with other matter, the "pieces" start orbiting one another. As other pieces join the group, they influence all the other pieces in the group simultaneously, so the whole set of objects tends to change it's axis of rotation as a group. In the end, there is a cluster of objects that all tend to rotate within the same general plane or around the same axis of rotation.\n\nFor example, most of the planets in the solar system rotate on an axis that is very similar to their axis of revolution around the sun. This is because the "pieces" of mater that formed the solar system started rotating around (orbiting) one another in a single plane. As some of the pieces crashed into one another and combined into planets, stars, etc. some of the orbital energy was transformed into rotational energy, but with angular momentum in the same direction as the rotational energy. Thus revolution and rotation are generally in the same direction with similar axes.
589353
Neptunes axis spins counter clockwise. the rest also do the same except three of them; venus:clockwise, Uranus: rotates on side, Pluto: rotates down
45656
Designated 2003 UB313 (it hasn’t been officially named yet), this “planet” is slightly larger than Pluto, has a small moon and takes more than 500 Earth years to orbit the Sun.\nA planet is a body large enough that, when it formed, it condensed under its own gravity to be shaped like a sphere. It orbits a star directly and is not a moon of another planet.\n To simplify things, some scientists propose that the size of Pluto be designated the smallest size for a planet. If that argument carries the day, we now have 10 planets, since 2003 UB313 meets all the criteria.
790318
Let's consider the possibilities and address them one at a time.\n\n1) There is a large planet on the opposite side of the sun from Earth.\n\nThis has been proven not to be the case. Such a planet would cause the other planet's orbits to "wobble" in ways that have not been observed and besides, none of the probes which have been sent to other planets has observed any planets "hidden" behind the sun.\n\n2) There is a large planet in the outer reaches of the sun's gravitational field.\n\nWhile this is in fact a possibility, it is highly unlikely. Typically when "solar" systems are formed, the distribution of the planet sizes follows a roughly gaussian distribution, with the larger planets in a huddle (in our case, Jupiter, Saturn and to a lesser extent Uranus and Neptune). If there was a large planet in our solar system out beyond Pluto, it would be difficult to see, however there would be no other stars near enough to pull it away from the sun. It may, for example be hidden by the sun, but so far away that no "telescopes" on probes are powerful enough to see it (refer to option 1 above).\n\n3) There is a large planet made of anti-matter in the inner solar system (closer to the sun than Pluto) which we cannot see.\n\nThis is not possible. The visible planetary orbits would be perturbed, and we don't observe that.\n\n4) I have run out of options.\n\nThis is VERY possible!\n\nSo, there you have it. Make up your own mind.
268015
The matter that made up the sun and planets existed at one time as a very large disk. As the matter clumped together, it was already on the same plane. That's the theory, anyway.
179307
Planets do not follow the same exact pathway. They are farther away from the sun. However, they still do rotate around the sun. (If they were in the same line, the planets would collide) The farther out the planets are, the longer time it takes them to revolve around the sun. This is why pluto takes an extremely long time to revolve once around, while the Earth year is only 365 days. Mercury has a year even SHORTER than the earth@
147445
Its all relative..usually we use sun as a point of a reference when we talk about relative size of planets which circle it. Pluto is about the same size as mercury.
707945
Earth's graceful 24-hour rotation rate is one of the traits that makes our planet so friendly to life, allowing most parts of Earth to stay a nice, comfortable temperature as they are bathed in sunlight during the day and darkness at night. \nEach planet in the solar system has its own unique rotation rate. Tiny Mercury, sizzling closest to the Sun, takes 59 Earth days to turn around just once. Venus, the second planet, rotates once every 243 Earth days. What's more, Venus rotates backwards from the direction of its orbit around the Sun, as do Uranus and tiny Pluto. Uranus even lies down on the job, rolling around with its axis of rotation pointed nearly toward the Sun.\n\nWhy do Earth and the other planets rotate at all? It will help to understand how our solar system formed. Almost five billion years ago, our solar system had its beginnings as a vast cloud of dust and gas. The cloud began to collapse, flattening into a giant disk that rotated faster and faster, just as an ice skater spins faster as she brings her arms in. The Sun formed at the center, and the swirling gas and dust in the rest of the spinning disk clumped together to produce the planets, moons, asteroids, and comets. The reason so many objects orbit the Sun in nearly the same plane (called the ecliptic) and in the same direction is that they all formed from this same disk.\n\nYou can visit this nasa site which has audeo narration and animation on earth rotation.\nhttp://spaceplace.nasa.gov/en/kids/phonedrmarc/2003_march.shtml
337086
The planets are actually trying to move in a straight line at a high speed due to the intertia from some force long ago.  When two objects are moving by each other, their gravity interacts and pulls them toward each other, bending the path that would otherwise be a straight line.  If they are too massive and too close, the gravity pulls them so much that they collide.  If things are balanced just right, the path is bent into a complete ellipse.  It's an ellipse instead of a circle because the sun is actually also being pulled a tiny bit toward the earth, as well.\n\nYou could consider gravity to be sort of a "perpendicular inertia", and the planets would revolve around the sun FOREVER if there were no other forces involved.
543004
Technically, the general rotation direction of the Sun and most planets is a leftover from the original solar nebula from which the Solar System formed.  As the planets and Sun coalesced, they retained the rotation direction of the original nebula.\n\nDuring the coalescence phase, asteroid-size chunks collided and stuck together.  As more and more of these chunks collected, the planets grew in size.  However, these chunks not only brought mass to the mix, they also brought momentum.  Since most of the materials were probably all travelling in more or less the same direction, the general rotation direction of the growing planets remained the same.\n\nIn the case of Venus and Uranus, it is suspected that a major collision between the planet and another body literally tipped the planets over due to an off-center orientation of the collision.  Uranus tipped over on its side, probably due to its size relative to the other body.  Venus, being smaller, tipped so far over that its rotation was reversed.
513817
The path you're talking about is called the 'ecliptic.' However, the sun doesn't follow the ecliptic but is instead its focus. That the planets all generally follow the ecliptic strongly suggests that they all formed at about the same time and within the same nebula from which they drew their material.