HISTORY OF ASTRONOMY

Before modern technology of astronomic styles, observatories were being made by our early ancestors. As a matter of fact, man is very fond of the sky and its bearings. People of the old ages believed many stories, and that stars will show you your destiny. Then there came the 11th century, where already the Babylonians could already tell time and where they were.

THE RETROGRADE MOTION

The Retrograde motion, however is recently studied, this motion is when the appearance of a celestial body (e.g. Mars) moves from east-to-west and then loops briefly (occurs once a year). Modeling celestial motion is also very important to understand why a celestial body would loop backwards.

THE MODELS

There are two different types of models. The first one named the geocentric model was designed by philosopher, Aristotle. It basically meant that all celestial bodies revolve around the Earth. It also began the study of a celestial sphere where the planets, Sun, and Moon would be rather attached to the Earth. There is another model, however, which involves that everything revolves around the Sun. This model is made Copernicus and is called the Heliocentric Model. This model explains the retrograde motion as an illusion instead of reality as said by Aristotle. The model upgraded by German Scientist Kepler that instead of celestial spheres, they were actually ellipses. The ellipse was the completion of the new theory of the Heliocentric Model. The ellipses theory was used to find the planet Neptune.

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