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   Timeline of Heliocentrism
 Key milestones in the understanding of our planet's place in the Universe


~8-9th Century BC    The idea that the Earth is in motion around the Sun is proposed in Sanskrit texts in ancient India.  It is the first recorded evidence of heliocentrism.

4th Century BC   Greek philosopher Heraclides Ponticus proposes that the apparent daily motion of stars is created by the rotation of the Earth.

3rd Century BC   Greek astronomer Aristarchus of Samos advances heliocentrism in a now lost book.  The ideas of Aristarchus, however, were
described in a book by the great philosopher and scientist Archimedes called The Sand Reckoner.

2nd Century BC   Babylonian astronomer Seleucus of Seleucia proves support for the heliocentric theory by his study of ocean tides.

150 AD   Greek scientist Claudius Ptolemy publishes the Almagest, a scientific treatise which proposes a geocentric, or Earth-Centered model of planetary motion.  The Geocentric Model (also called that Ptolemaic Model) remained the accepted model for over a thousand years in the Western world.

9th century   Afghan astronomer Ja'far ibn Muhammad Abu Ma'shar al-Balkhi develops a model of planetary motion which proposes that all planets revolve around the Sun.

1543   Nicolaus Copernicus publishes De revolutionibus orbium coelestium (English: On the Revolutions of the Heavenly Spheres).  It is the first scientific treatise to provide detailed scientific support for heliocentrism.

1603-1605   Johannes Kepler discovers the three laws of planetary motion.  His work would provide the scientific basis for a broad acceptance of the heliocentric model later in the century.

1633   Galileo Galilei is sentenced to prison by the Inquisition on the charge of heresy for advancing the Copernican model of planetary motion in his book, Dialogue Concerning the Two Chief World Systems.

1687   Sir Isaac Newton publishes Principia Mathematica.  This highly influential work describes the physical laws that govern the motions of planets.

1757   Pope Benedict XIV suspends the Catholic Church ban on works that support the heliocentric model.