tt40 wrote:
It then maps out the long-arm of the ellipse and
gravitational attraction recedes just a little bit, allowing it to
'stretch that circle'.

Are you asking why it is an ellipse rather than a circle? If
so, the answer is easy. You can create a perfectly circular
orbit with only two bodies --- the sun and the planet. But
when you introduce everything else, they will not stay
perfectly circular. And, given the chaotic nature of the solar
system's creation, it is too much to ask that it create
perfectly circular orbits at the start.

A circle and an ellipse are the only two possibilities that
work. And to be "perfect" about it, they aren't even perfectly
elliptical. There is always a little tugging and pulling by
other bodies that alter the orbits from perfect. But apart
from those tiny imperfections, they are ellipses.

Hope this helps.

Chuck Taylor
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