Newton was an English physicist, scientist, astronomer, and mathematician, that invented a new form of math, discovered the secrets of light and color, and described how the universe was held together. He was one of, if not the most influential figure in the science of astronomy.
Gravity and the motion of Planets.
Newton says that the law of universal force came to him one day when he was sitting in his garden drinking tea, when an apple fell out of a tree. He suddenly realized that the same force that pulled the apple toward the Earth also keeps the moon in its orbit. He also found that the force which he called "gravity" is what makes all the bodies in the universe attract each other. In 1687 Newton published his finding in the Mathematical Properties of Natural Philosophy. It is now considered the single greatest contribution in the history of science.
Light and Color.
Newton's discoveries in optics were equally spectacular. He bought a prism in order to better study the separation of white light. He found that
white light is actually created by a mixture of all the different colors. He continued to study the many different elements of light and published the finds of all his experiments in Opticks in 1704. Today these finds help scientists determine, the chemical composition, temperature, and even the speed of a distantly glowing star or even an object that has been heated in a laboratory. He also took this newly acquired knowledge of light and developed a new type of telescope. Instead of using a series of lenses, in his telescope he used a reflecting mirror. Newton's first new reflecting telescope was only six inches long and through it Newton saw Jupiter's satellites.