Dinesh_college Posted September 10, 2005 Report Share Posted September 10, 2005 We all know about gravity.By Newton's law the force acting between two objects in space is given by GMm/r^2.So there will be some force acting between our Earth and Sun. Why not the Earth is pulled towards the sun? Why the Earth is revolving the sun in elipsoidal path? Quote Link to comment Share on other sites More sharing options...
Boerseun Posted September 10, 2005 Report Share Posted September 10, 2005 We all know about gravity.By Newton's law the force acting between two objects in space is given by GMm/r^2.So there will be some force acting between our Earth and Sun. Why not the Earth is pulled towards the sun? Why the Earth is revolving the sun in elipsoidal path?Hi Dinesh Indeed, the Earth is being pulled to the Sun. But centrifugal force keeps the Earth in what we'd call an orbit. You can liken it to a satellite, which is also falling towards Earth - but the rate at which the Earth's surface curves away is roughly equal to the speed at which the satellite falls. So the satellite just keeps going round and round due to its forward speed. You can say that we are forever falling towards the Sun, but we keep on missing! Meteorites seen at night is examples of failed orbits - they didn't have the right initial speed or angle to achieve a workable orbit around the Earth, and hence burnt out in the atmosphere. For a planet, achieving an orbit is a hit-or-miss affair. If you keep in mind the vast size of our solar system, and ponder the fact that only 9 (okay - ten!) planets made it, the rest either fell towards bigger planets or crashed into the Sun - then you'd think we're pretty lucky to be here. Which we are. But - if the Earth fell into the Sun a few million years ago, we wouldn't be here to wonder about it! :shrug: Quote Link to comment Share on other sites More sharing options...
UncleAl Posted September 10, 2005 Report Share Posted September 10, 2005 The Earth orbiting the sun, or any satellite in orbit about its parent body around their mutual barycenter (e.g., the moon and the Earth) is in free fall. It is always falling into the barycenter. http://spaceplace.nasa.gov/en/kids/barycntr.shtml http://en.wikipedia.org/wiki/Barycenter The trick to an orbit is to have the free-falling satellite always miss hitting the parent body. If you like math, the centripetal force is always equal and opposite to the gravitational force. This condition is satisfied by an ellipse (one focus being the barycenter). A circle is a special case of ellipse in which both semi-diameters are equal. http://en.wikipedia.org/wiki/Kepler#Kepler.27s_laws Quote Link to comment Share on other sites More sharing options...
Qfwfq Posted September 12, 2005 Report Share Posted September 12, 2005 It isn't all that difficult Boerseun for an object to be in orbit around the Sun. It's actually a lot less easy for it to fall into the Sun. If you like math, the centripetal force is always equal and opposite to the gravitational force. This condition is satisfied by an ellipse (one focus being the barycenter). A circle is a special case of ellipse in which both semi-diameters are equal.The two forces are always equal only in the case of the circle. When the orbit is elliptical, each of the forces will become alternately more and less than the other, as the planet goes from perihelion to aphelion and vice versa. Quote Link to comment Share on other sites More sharing options...
GAHD Posted September 12, 2005 Report Share Posted September 12, 2005 It's like teather-ball, without the pesky drag of the atmosphere or the rope winding up too much. Quote Link to comment Share on other sites More sharing options...
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