Hi i´m not sure if someone posted this already also i´m not sure why it bit me not before why the hell are the plants floating in an circle around the sun? if i´m correct, the correct planet runway is an oval how i think thats an serious balance problem because of the travel speed.
Circular is just the default orbit. You can have elliptical orbits if you want. I'm pretty sure those bugs were fixed.
My degree in Mathematics tells me that a Circle is, by definition, an Ellipse with an eccentricity of 0 and convergent focus points. And that both of the above shapes are actually a subset of Conic Sections. Math is fun! Wheee!