What is Heliocentric Vs. geocentric theory?

Answer 1

The Difference is that a heliocentric model says that the sun is in the center but not the exact center and all the other planets and the moon orbit the sun. But a geocentric model states that the earth was in the center and that the sun moon and stars all went around earth. That is the difference.

Heliocentric:

Also, All the planets revolve around the sun.

Stars are very much farther away than the Sun.

Any motion of the stars is a result of the Earth's rotation.

Any movement of the Sun is due to Earth's rotation and revolution about the sun.

The heliocentric model were ellipses NOT circular orbits.

Geocentric:

Epicycles added to epicycles.

Precision timing for Venus and Mercury.

Earth placed "off" center.

The Earth is located at the center of the universe and all the planets revolve around the Earth.

Answer 2

The two theories differ in what occupies the centre of the solar system. Is it the Earth (the geocentric theory) or the Sun (the heliocentric theory)?

We now know the Sun is at the centre because in the 18th century it was found that it is by far the most massive object in the solar system. Also, with the right equipment we can see the positions of the nearest stars change as the Earth moves in its orbit round the Sun. So the heliocentric theory rules.

Before that the geocentric theory was used, based on a literal interpretation of The Bible. Ptolemy's theory with the Earth at the centre used a system of circles and epicycles to predict the positions of planets, and it worked quite accurately.

The heliocentric theory was proposed by Nicolas Copernicus in the early 1500s. Later Galileo had a famous dispute with the Catholic Church over it. Galileo started by saying he had proofs of the heliocentric theory but the Cardinals were too stupid to understand them. Eventually he was forced to admit there was no proof based on the scientific evidence available at that time.

The proof came in the next century after Newton's laws of motion and law of gravity were used in detailed calculations that explained the planets' orbits and allowed the mass of the Sun and planets to be calculated.