History of Astronomy - Uniting Physics and Astronomy

Uniting Physics and Astronomy

Although the motions of celestial bodies had been qualitatively explained in physical terms since Aristotle introduced celestial movers in his Metaphysics and a fifth element in his On the Heavens, Johannes Kepler was the first to attempt to derive mathematical predictions of celestial motions from assumed physical causes. Combining his physical insights with the unprecedentedly accurate naked-eye observations made by Tycho Brahe, Kepler discovered the three laws of planetary motion that now carry his name.

Isaac Newton developed further ties between physics and astronomy through his law of universal gravitation. Realising that the same force that attracted objects to the surface of the Earth held the moon in orbit around the Earth, Newton was able to explain – in one theoretical framework – all known gravitational phenomena. In his Philosophiae Naturalis Principia Mathematica, he derived Kepler's laws from first principles. Newton's theoretical developments lay many of the foundations of modern physics.