Geocentrism vs. Heliocentrism


Geocentrism, The Geocentric theory

The Geocentric theory is a cosmic perspective in which the Earth is at the center, and all the stars revolve around the Earth.
From the 13th to the 17th century, it was a widely recognized worldview in Christian societies, including the Roman Catholic Church.

Heliocentrism, The Copernican theory

The Copernican theory is a cosmic perspective in which the sun is at the center, and the earth and other objects are circling the sun. In modern times, we think that the sun is just one of many stars.
Some of the ancient Greeks believed that there were people who believed in the earth movement. However, the mathematically perfect Copernican theory model was presented by Copernicus in the 16th century.

Evidence of Heliocentrism

Venus' size change
Because Venus cannot reflect all of the sun's light when it is close to Earth, it always has a half-moon shape. And it's very big.
When Venus is far from Earth, it is round like a full moon, but smaller in size. All of these facts require that the sun is at the center of its rotational motion.

Elongation and Phase of Inner Planet

Stellar parallax
It is a phenomenon in which the parallax of nearby stars changes with a period of one year due to the orbit of the Earth. This also happens only when the Earth orbits the Sun.