Do you think early astronomers would have proposed circular or elliptical orbits for the planets?

Question

WHY did they change thier thinking

Answer 1

They proposed circular at first and then later found them to be elliptical.
I know that Copernicus was the first to have a model of the planets orbiting the sun and he used circular orbits because that is how they appear. They changed when astronomers did the calculations and actually found that the orbits were elliptical.
Im trying to find the person that did this.
It was Johannes Kepler
http://en.wikipedia.org/wiki/Kepler

Answer 2

The earliest astronomers all proposed perfectly circular orbits of the planets and stars around the earth due to a very simple reason: philosophically speaking, the heavens were a perfect and precise place of peace and flawlessness. The circle was the perfect shape, and thus, the heavenly bodies by default HAD to circle the earth in well, perfect circles...

Well, actually, the theory was far more like a spiral-graph in order to explaine apparent retrograde motion in the geocentric model, but that's another story entirely. Orbiting in circles within circles.

Answer 3

How early is "early"? Elliptical orbits were first proposed by Kepler, some 400 years ago. Before him, astronomers (at least those who didn't believe in a geocentric model) believed that the orbits were circular.

See the link below for details.

Answer 4

Why are you asking for speculation on what they *would have* proposed, when there is plenty of information available on what they *did* propose?

Pretty much everyone who recorded any opinions on the question believed in orbits that were based on circles, because everyone "knew" that the heavens would move in perfect paths. Of course, Ptolemy had to resort to multiple epicycles (circles rotating on other circles) to come up with a reasonable approximation of planetary motion.

Even Copernicus, though he realized you could greatly simplify this complexity by assuming the planets revolved around the Sun, not the Earth, persisted in using circles and epicycles to define orbits.

Kepler finally realized that planets orbited in ellipses, but not before he had spent years trying to fit the orbit of Mars to various circle-based paths.