Prior to Newton's ideas, it was generally believed that the natural state of an object is to be at rest. It was also believed that different phenomena govern the earth and celestial bodies. Newton's laws of motion and gravity showed that the same laws govern terrestrial and celestial phenomena. Newton's work explained why planets rotate around the sun and why they don't fall into each other. Conservation of momentum and energy is derived from Newton's works and explains a number of celestial observations. We now understand why bodies (whether at microscopic or celestial scale) attract each other and by what force. Conservation of angular momentum provided us with valuable reasoning for the formation of stars and galaxies. Newton's work also extended Kepler's law and showed that ellipses are not the only possible orbits for planetary motion; others include parabola and hyperbola.

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