how does gravity keep a planet moving in an orbit around the sun?
375266
Gravity is a force that accelerates two masses directly towards each other. In order for the masses to not simply crash into each other, one of the masses must have some nonzero velocity relative to the other mass that is not directed along the line between them. \nAssume one mass is larger than the other. It takes some time for the smaller mass to hit the larger mass under the pull of gravity. If we give the smaller mass a velocity perpendicular to the line between the two masses, the mass may "miss" the larger planet before it falls all the way to the surface, and continue to do so. The range of velocities can make this continual freefall take shapes from a perfect circle (the perfect tangential velocity, which has almost zero probability) to ellipses, and with high velocities from parabolas to hyperbolas.\nA velocity too small will simply increase the amount of time before the planets collide, these are spirals.
182160
First of, there's no force causing planets to rotate. \n\n"Most of the rotation comes from the conservation of angular momentum. The formula is 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). \n\nAnyway, 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."
398654
In the special case where centrifugal force exactly balances gravity, the orbit IS circular.  But say you have a planet in a circular orbit.  Give it a little extra speed in the direction it's going.  Now it has too much centrifugal force, and it begins to gain distance from the star -- but that means it's gaining potential energy and so must be losing kinetic energy.  So it slows down.  The detailed math shows that by the time it's gone 180 degrees around it has lost so much speed that, even though it is farther from the star, now it doesn't have enough centrifugal force to counteract gravity, so it begins to speed up.  Again, if you do the math, you see that it will return to the exact position it was at when you gave it the extra push, and with the exact same velocity it had just after that push.  So it will just keep repeating that orbit, which is highest (and slowest) at one point and lowest (and fastest) 180 degrees around; in other words, an elliptical orbit.
125865
Kepler's Laws \nIllustration of elliptical orbit of a planet with the sun at the left focus. The semi-major and semi-minor axes are denoted by  and . The shaded triangular area element is needed for the discussion of Kepler's second law. Perihelion and aphelion are respectively the points on the orbit nearest and farthest from the sun. Note that at perihelion and aphelion the velocity is purely tangential, i. e., the velocity component along the radius vector is zero.  \nJohannes Kepler, using data compiled by Tycho Brahe, inferred three laws governing the motions of planets in the solar system: \nPlanets move in elliptical orbits with the sun at one focus. \nEqual areas are swept out in equal times by the line connecting the sun and the planet. \nThe square of the period of revolution of the planet around the sun is proportional to the cube of the semi-major axis of the ellipse. \nThese laws were instrumental in the development of modern mechanics and the universal law of gravitation by Isaac Newton. \nShowing that the first law is consistent with Newtonian mechanics is mathematically more difficult than we can undertake in this course. However, the second law turns out to be a simple consequence of the conservation of angular momentum. It shows an elliptical orbit with the area swept out as a planet moves from position 1 to position 2. We estimate this area as , where we have ignored the small unshaded part of the area to the right of the shaded triangle. The distance traveled by the planet in time  is , so the magnitude of the velocity is . However, in computing the angular momentum, we need the tangential component of the velocity, i. e., the component normal to the radius vector . This is simply . The angular momentum is , where  is the mass of the planet. Combining this with the formula for  results in \nSince gravitation is a central force, angular momentum is conserved, which means that  is constant. Thus, we have shown that conservation of angular momentum is equivalent to Kepler's second law. \nKepler's third law turns out to be a consequence of the universal law of gravitation. We can prove this for circular orbits. We know that a planet moving in a circular orbit around the sun is accelerating toward the sun with the centripetal acceleration , where  is the speed of the planet's motion in its orbit and  is the orbit's radius. This acceleration is caused by the gravitational force, so we can equate the force divided by the planetary mass to , resulting in where  is the mass of the sun. This may be solved for Eliminating  in favor of the period of revolution  results in ...This agrees with Kepler's third law since the semi-major axis of a circle is simply the radius .
679561
Earth and all the planets in out solar system are orbiting our Sun. The Sun and all stars are moving in space, but those other stars are not moving around US; they are orbiting the center of the Milky Way galaxy. Because the stars are so far away from us it takes thousands of years before they have moved far enough for us to notice it from so far away, but astronomers have made careful measurements with telescopes and can detect small position changes, which they call "proper motion". I googled "proper motion" and below is the first result.
563922
They don't. They calculate the MASS of a planet by carefully obseving it's behavior in the gravitational field of the sun or star it orbits, and by using Keppler's Laws of Planetary motion and Newton's Laws of motion.
599254
The Sun, its pull is making the planets in this system orbit.
1022705
The sun keeps the planets in an unwavering orbit, which keeps the hunks of rock from spilling out into the universe. As time goes on, the sun expands, but not even noticeably for millions of years, which will in time envelop the planets around it, and implode into a white dwarf (dead star).
566885
Not only by the sun;s gravity,coz otherwise they would rush into yhe sun.they have a certain centrifugal force of their own,which keps the 2 forces balanced,and their moton remains cinstant.the closer a planet,the higher sun;'s gravitational pull towards it,hence it has higher centrifugal force,that is,it rotates more quickly on its axis.
54730
Not clear what you mean?  How does it stay up in space? It does that because it is going very fast, which would take it away from earth, but gravity is pulling it back, causing it to curve, and go around the earth, just like a string on a yo-yo if you just whip it around your head. \n\nIf you mean, what does it do, there are different kinds, but most of them get power from solar panels, and have radio receivers and transmitters to communicate back to earth.
1072334
The sun DOESN'T know the ship is there, and it doesn't have to:  Gravity is a warping or deformation of the four-dimensional fabric of space-time, not an actual pulling.\n\nThe earth travels around the sun because the earth is actually travelling IN A STRAIGHT LINE in its "local" space.  The end result is an ellipse because the space around the sun is literally bent into a curved shape.\n\nSo, your ship can travel faster than light, but it can't travel faster than space -- which is to say, wherever it arrives after its hyperspace trip -- it IS where it IS and if the space is bent the ship will follow the contour of its local space regardless of how far it is from the source of the gravitational spacetime warping.  No information or "graviton" needs to actually travel from the ship to the sun.
20941
Consider that the Earth moves around the Sun because of gravity, like a ball on a rope moves around your hand when you swing it.\n\nNow, consider some of the laws of gravity (in english):\nCloser objects = more gravity to eachother\nBIGGER objects = more gravity to them\n\nThe Earth is 1/100000(lots of 0's, maybe more) the size of the Sun, so we really don't affect it much, but it keeps us going around it like nuts! (once a year, right?)\n\nThe Moon, however, is not sooooo different from the size of the Earth (yes it's smaller, but not 1/10000etc(like the Earth vs. Sun thing), AND it's CLOSER to the Earth than the Sun is (WAY CLOSER)!\n\nSo because it's kindda nearer to our size, and it's kindda close, it's got 2 big check-marks for LOTS-O-Gravity!
262658
The orbit of Mercury describes roughly a circle.  If the gravitational attraction of the sun instantly disappeared (a mental exercise) Mercury would fly off into space on a straight line tangent with the circle and at the instantaneous velocity it had at the instant of departure.  It does not fly off into space solely because it is always falling toward the sun at the correct rate to keep it on the circle.\n\nAs such, Mercury has kinetic energy (of motion) equal to one half times its mass times its velocity squared which is an enormous amount of energy.  To move mercury using solar energy you likely would likely have to collect a substantial part of the solar wind and direct in onto Mercury (without burning it!).  To Move mercury to a higher orbit you would need to accelerate it in a direction always tangential with its orbit to increase its kinetic energy.  To make an ititial estimate of the energy needed, I'd suggest using what I call a "technical tithe" or 10% of what you wish to change.  For example if you have 100 pounds twins balanced on a seesaw and hand one a 10 pound weight it should noticeably change the balance whereas a few grams nay not be noticed.  Therefore, calculate 10% of Mercury's kinetic energy and that is about the amount you may have to add to make a significant change.  That will require a huge force even if exerted constantly over a long period of time to reach the calculated amount of added energy.  Good luck.
804445
First you want to know the acceleration due to gravity of the planet Glob. At the surface the gravitational acceleration (g) can be determined by equating the weight of an object with the gravitational force law\n\nm*g = G*M*m/R^2\n\nwhere R is the radius of Glob, M is Glob's mass, G is the universal gravitational constant, and m is the mass of the object. Solving for g yields\n\ng = G*M/R^2\n\nNow, throwing an object into the air, and neglecting air resistance, we can consider conservation of energy. The kinetic energy of the object when it is released by the astronaut is completely converted into potential energy when the object reaches the top of its travel.\n\n0.5*m*V^2 = m*g*H\n\nwhere V is the initial speed of the object and H is the height to which it traveled, and g is the gravitational acceleration solved for above. Solving for V we find\n\nV = sqrt(2*g*H).\n\nThe satellite traveling in a circular orbit of radius D above the planet has its centrifugal force balanced by the gravitational force of the planet.\n\nFc = m*v^2/D = G*M*m/D^2 = Fg\n\nSolving for the speed of the satellite (v) needed in order to maintain orbit at radius D yields\n\nv = sqrt(G*M/D).
384805
The First law of Kepler is: \nPlanets move along elliptical orbits with the Sun\nat a focus.\n\nSo, all i can say is that the sun is relatively stagnant in our immediate universe.\nThe earth rotates along an elliptic orbit around the sun.\nThe moon rotates along an elliptic orbit around the earth.\n\nWell, all "movements" are relative to some reference point.
876446
The sun rotates on its own axis that what causes the gavational pull to keep the planets moving around it.
281335
The law you are referring to is the law of inertia, which is directly related to the laws of gravity.  The heat from the sun and it's gravitational pull are what "make the earth go round"