Planets in gravitational well
Far in space, gravitational force coming from one direction is almost cancelled by gravitational force coming in opposite direction. An object in that position continues in strait line because the net force on it is zero.
Because of all its atoms, the sun blocks some of that gravitational force around itself. An object located in that space is pushed towards the sun because gravitational force coming from direction opposite to the sun is bigger now.
Gravity from space is blocked partially by the sun; gravity density is lower close to the sun and increases according to 1/distance squared.
But the sun itself is also an emitter of gravity. That means close to the sun gravitational force is bigger that in space around. That extends to a certain distance from the sun.
At a certain distance, the density of gravitational force from one side is almost equal to the density of gravitational force coming from the direction of the sun.
That makes a kind of big sphere where gravitational force is almost equal on each side on a line pointing toward the sun. That region or bubble is the gravitational well . Planets cannot go in strait line because in doing so, they enter a region where the gravitational force from outside is now bigger and they are pushed back towards the sun. When they approach the sun, the same thing happens in opposite: the gravitational force coming from the sun is now bigger and the planet is pushed away, In that manner, the planet goes around the sun and is a satellite.
Region around the sun emitting in all direction added to what is emitted from space causes a different density region.
If we add the gravitational force from the sun and from space, we have something similar to that drawing, showing the low density of gravitational force all around the sun.
The graph shows where the planets are in that ‘well‘; they are all situated in the brown rectangle, at a distance between 5.80E+07 m and 6.00E+09 m.
In order to show the gravity well, we must use the log value of the distances. The blue line is for the gravity from space that was partially blocked by the sun and the red line is the gravity emitted by the sun. It goes to almost zero at far distance.
In this graph, the sun center is at 0 on x-axis.
Xcell sheet for these calculations:
|distance||sun – planet|
|planet||planet||from sun||mass kg||force in N|
|in log||in log|
The mass and the speed of the planet will permit to find an equilibrium point and it becomes a satellite to the sun. Small planets are far…
The gravitational force in this graphic represents the net total force when we add opposite forces. Depending on its speed, the planet finds the distance away where the force towards the sun equals its centripetal force.
Einstein seem to have a vague idea of that gravity well and tried to explain it with his theory of space time curvature. Space is not curved but its different density will influence objects towards the sun as if it was “curved’ inward.
Following the equation (F = Gmm/dd) there is a possibility to have planets between the sun and Mercury if the speed is big enough. There is no such planet there. This is because of the gravity well described here. A planet closer to the sun would be pushed away by sun radiation of gravity.
This also explains why most comets do not fall into the sun as they should because of the pressure of the gravity emitted by the sun. It will push the comet’s tail away from the sun.