An example of an (historic) alternative conception:
"…the godlike circular movements of the world…
we will recall that the movement of the celestial bodies is circular. For the motion of a sphere is to turn in a circle; but this very act expressing its form, in the most simple body, where beginning and end cannot be discovered or distinguished form one another, while it moves through the same parts in itself. …
We must however confess that these movements are circular or are composed of many circular movements, in that they maintain these irregularities in accordance with a constant law and with fixed periodic returns; and that could not take place, if they were not circular."
Nicolaus Copernicus (1543/1995) On the Revolutions of the Heavenly Spheres (Translator: Charles Glenn Wallis) Amherst, New York: Prometheus Books.
Copernicus's On the Revolutions of the Heavenly Spheres (1543) is widely considered a key work in revolutionising astronomy, in particular in his arguments for the movement of the earth through space. In some senses though Copernicus is conservative, accepting ancient notions about the movement of the planets needing to be circular, or combinations of circular motions.
Read about conceptions of planetary orbits
