Do the planets go around the Earth or the Sun?

Hopefully, you know the correct answer! The Sun is at the center of the Solar System and planets revolve around it. But people haven't always known about this.

Dive into the history and explore the development of the geocentric and heliocentric models of our Solar System!

## Heliocentric vs. Geocentric

### The Heliocentric Model

Assumes that the Sun is at the center of the Solar system and the Earth and other planets go around it.

### The Geocentric Model

Assumes that the Earth is at the center of the Universe, and the Sun, the Moon, and the other planets go around it.

The video below shows the difference between geocentric and heliocentric models. The heliocentric model is on the left and the geocentric model is on the right.

## Geocentric Model

Ancient Greek astronomers observed that the Sun, Moon, and planets appeared to revolve around the Earth once per day. While observing, it seemed to them that the Earth was motionless and stable. So, they developed the geocentric model with the Earth at the center of the Universe.

An ancient Greek astronomer named Eudoxus was the first to develop the geocentric model of the Universe around 380 B.C.

Claudius Ptolemy, an Egyptian astronomer, provided detailed mathematical calculations to explain the movements of heavenly bodies within the geocentric model.

Only by the late 17th century, with further developments in astronomy, was the geocentric theory rejected.

## Heliocentric Model

In the Third Century B.C., Aristarchus of Samos suggested that the Sun could be at the center of the solar system. At that time, his idea didn't become popular because there weren't any mathematical evidence or detailed observations. Also, the geocentric model was supported by influential philosophers like Aristotle.

Only in 1543 after Nicolaus Copernicus published a book about the movements of heavenly bodies did the idea of the heliocentric model start to become popular.

Nearly a hundred years after Copernicus introduced his theory, scientist Galileo Galilei used his telescope to confirm the heliocentric model. Astronomer Johannes Kepler and physicist Isaac Newton accurately calculated how planets move around the Sun.

#### Quiz

Bob wants to have a ride around the Earth. Which celestial body should he hop on?

## Take Action

The heliocentric model helps us accurately understand how our Solar System works. This understanding is crucial for advancements in astronomy, space exploration, and our broader understanding of the universe.

What else can you do to learn the topic better?