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The Geocentric model

Aristotle

The earth is the centre of the universe.

The earth does not move, and it has planets orbiting it.

All the celestial bodies, with an exception to Earth, were circular, and that if they were circular, they could orbit Earth forever.

b) Ptolemy (Claudius Ptolemaeus)

Claudius Ptolemaeus was agreeing the statement of Aristotle that the earth was in the centre of the universe.

Claudius was using maths to make this true, and for that the said that the planets must move in epicycles, smaller circles.

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The heliocentric model

This model it defines that the sun is the centre of the universe, which was proposed by Nicolaus Copernicus in sixteenth century.

He says that the retrograde effect of some planets is an optical effect.

2. THE CURRENT UNIVERSE

From 16th century when galileu invented the telescope is improved the observation of the universe.

Binoculars and telescopes: for hobbyists.

Giant telescopes: use to observe distant bodies. They are in special places where the observation is better.

Radio telescopes: pick up radio waves emitted by some stars, which are received by antennas and complement telescope studies.

Space telescopes: they are giant telescopes that observe from space and allow to photograph very distant galaxies in great detail.

3. THE BIRTH OF THE UNIVERSE

Thanks to all the knowledge we have of the universe, there are several theories of how it was formed.

By analysing the light of the stars, it was discovered that the galaxies are moving away from each other and that this is because of a great explosion (Big Bang) that occurred 13.8 billion years ago.

Since then, the Universe has been growing in size and cooling.

	Created by RAJAN BALIGE JEKETE 9 months ago

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