Please forgive my ignorance, but would the relative lack of eccentricity WRT Neptune and Terra Firma on the Ecliptic indicate something like Neptune being a dying star of sorts, perhaps central to the formation of Earth - sort of like us all exploding outward from somewhere else and settling around nice ol' Sol? What also confuses is the retrograde rotation of Uranus (or is it Neptune?).
Great thread, thank you so much for keeping this beancounter on your ping list.
OK - Back in the day, planets orbited stars/suns... moons orbited planets...
Now, moons orbit stars/suns while being orbited by moons and being continually billed by Orbitz.
Man. This was much easier in grade school.
Neptune is smaller in diameter than Uranus, but a bit more massive; neither Neptune nor the other planets should be considered stars (dying or otherwise); Uranus is the planet with the axis tipped nearly into the ecliptic, IOW, one or the other of its polar regions faces the Sun during part of its orbit. Which is pretty wild.
Uranus should be excluded, its origin is obviously different from the other planets, and its axis is too freaky. :')
Now that Pluto is removed, Mercury is the smallest, and is too small, and its orbit is in precession, making it too weird to be considered one of the planets. :')
With the removal of Mercury, Venus is the only one left without a moon, which makes it too strange to remain. Out it goes. :')
Mars is also too small, and is less dense than the Earth. Also, it doesn't have proper moons (just oddly shaped space debris). Out it goes. :')
There are therefore only four planets -- Earth, Jupiter, Saturn, and Neptune.