The Moon's nearly
circular orbit shows that it was never torn from nor captured by Earth.b If the Moon formed from particles orbiting Earth, other particles should be easily visible inside the Moon's orbit; none are.
A comparison of stellar densities from asteroseismology with densities derived from transit models in Batalha et al. assuming
circular orbits shows significant disagreement for more than half of the sample due to systematics in the modeled impact parameters, or due to planet candidates which may be in eccentric orbits.
Not exact matches
Sommerfeld
showed how to extend quantum ideas from
circular to elliptical electron
orbits, making him kind of like a Kepler to Bohr's Copernicus.
The above image
shows the relatively
circular orbits of most solar system planets, and the the highly elliptical
orbit of Pluto.
The point of my argument was to
show that if that were true then the center of this
circular orbit would have to be on the opposite side of the Sun from the barycenter.