ZetaTalk: Elliptical Note: written during the 2001 sci.astro debates.

Clearly, more than the regular flow of gravity particles from and back into a Sun is at play in planetary orbits, else all these orbits would be circular. There are countless influences, but these influences can be summarized into their effect, which accounts for an elliptical orbit.

Secondary Gravity Influence
Planets that orbit both binary suns do so in a figure 8, pulling toward the second binary at the juncture where the planet is positioned between the binaries, but propelled by momentum to continue its orbital curve while moving toward the second binary. But planets caught between binary suns, but orbiting a single sun, pull wider toward the second binary in their orbit, creating an ellipse that leans toward the second binary.

Escape Attempt
Just as two North Poles in a magnetic object will avoid each other, pushing the lighter object to align with the heavier object, other repulsion forces can push an orbiting planet closer to its Sun than the flow of gravity particles would ordinarily allow, putting the planet in a squeeze between these repulsion forces. The result is a rush to leave the squeeze, such that the planet accelerates at this point in its orbit, giving it momentum as it stretches into the long part of the ellipse.

Dithering
Planets positioned such that they have several attractions can be slowed in their orbit due to dithering. Such dither points are not even in the orbit, so create a speeding up as the planet approaches the dither point, and a slowing down as it leaves this point. Rushing to an attraction causes the orbit to draw long at that point, a factor of momentum on the orbiting planet, which is an influence toward an elliptical orbit. Where no apparent gravitational giant exists to explain the elliptical orbit, particle flows other than gravity are the dominant influence on the shape of the orbit.