Difference Between Geocentric and Heliocentric Models

The key difference between geocentric and heliocentric models is that according to the geocentric model, the Earth is at the centre of the cosmos or Universe whereas according to the heliocentric model, the Sun is the centre and planets revolve around the Sun.

Geocentric and heliocentric models are very important in astrophysics. These models are useful in describing the occurrence of Sun and planets in the Universe.

CONTENTS

1. Overview and Key Difference
2. What is Geocentric Model
3. What is Heliocentric Model
4. Side by Side Comparison – Geocentric vs Heliocentric Models in Tabular Form
5. Summary

What is the Geocentric Model?

Geocentric model, in astronomy, is a concept that describes that Earth is the centre of the Universe. In other words, this is a suspended description of the Universe with Earth at the centre. Under this model, the Sun, moon, stars, and other planets orbit around the Earth. This was the predominant description of the cosmos in many ancient civilizations, including Aristotle in Classical Greece.

There are two major observations that were used in developing this model:

1. The Sun appears to revolve around the Earth once per day when observing from anywhere on Earth.
2. An earthbound observer sees no movement of Earth because it feels solid, stable and stationary.

Ancient Greeks, ancient Romans, and medieval philosophers tried to combine the geocentric model with the concept of spherical Earth instead of the model of flat Earth. This model entered the Greek astronomy and philosophy at very early times. E.g. pre-Socratic philosophy. In 4the century BC, Plato and his student Aristotle developed a structure for Universe based on the geocentric model. It included the Earth as a sphere which is stationary at the centre of the Universe. There were the stars and planets carried around the Earth on spheres or circles that were arranged in the order of Moon, Sun, Venus, Mercury, Mars, Jupiter, Saturn, and some other fixed stars.

What is the Heliocentric Model?

Heliocentric model in astronomy is an astronomical model in which the Earth and planets move around the Sun at the centre of the Solar system. This model is the opposite of the geocentric model. The concept of Earth revolving around the Sun was developed as early as the 3^rd century BC by Aristarchus of Samos. However, a proper mathematical heliocentric model was not proposed until the 16^th century. It was presented by the mathematician, astronomer, and Catholic cleric Nicolas Copernicus. This was named as Copernicus revolution. This development led to the following introduction of elliptical orbits by Johannes Kepler and supporting observations made using a telescope by Galileo Galilei.

Later, the scientists, William Herschel and Friedrich Bessel made observations and realized that the Sun is not the centre of the Universe but only in the Solar system.

What is the Difference Between Geocentric and Heliocentric Models?

Geocentric and heliocentric models are very important in astrophysics. These models are useful in describing the occurrence of Sun and planets in the Universe. The key difference between geocentric and heliocentric models is that geocentric model suggests the Earth as the centre of the cosmos or Universe whereas the heliocentric model suggests the Sun as the centre and planets revolve around the Sun.

Below is a summary of the difference between geocentric and heliocentric models in tabular form.

Summary – Geocentric vs Heliocentric Models

The key difference between geocentric and heliocentric models is that according to the geocentric model, the Earth is at the centre of the cosmos or Universe whereas according to the heliocentric model, the Sun is the centre and planets revolve around the Sun.

Reference:

1. “Geocentric and Heliocentric Models.” Astronomy, Available here.

Image Courtesy:

1. “Bartolomeu Velho 1568” By Bartolomeu Velho – Own work (Public Domain) via Commons Wikimedia
2. “Geoz wb en” – Original image by Niko LangSVG version by User:Booyabazooka – Own work (CC BY-SA 2.5) via Commons Wikimedia