Born in the small town in the then Roman empire, Johannes Kepler was the son of a mercenary soldier. Even as a young student, Kepler excelled in mathematics. His intelligence and hard work, earned young Kepler a special place in the hearts of his teachers. It was on the recommendation of one of his teachers that Kepler got an opportunity to work with the renowned Danish astronomer, Tycho Brahe.
These were times when it was believed that the Earth was the center of the Universe, and seven planets- Moon, Mercury, Venus, Sun, Mars, Jupiter and Saturn - moved round the Earth. Already several scientists were disputing this theory. Copernicus had put forth his "heliocentric theory" where he stated that the Sun was the center of the Universe, with planets moving around it. Kepler got his chance to not only prove this through mathematical calculations, but also define specific elliptical orbits for the planets' paths around the sun.
Kepler worked with Tycho Brahe and after his death, took over the mantle of Imperial Mathematician. Drawing data from Tycho Brahes observations and his own, Kepler formulated the three laws of planetary motion, which established the current theory that planets move in elliptical orbits around the sun.
Despite a number of personal tragedies, Kepler's involvement in his work did not wane. As one of the most respected and admired mathematicians of his time, Kepler had many "firsts " to his credit. He was the first to correctly explain planetary motion. Keenly interested in optics, he was one of the first to investigate the formation of pictures with a pin hole camera and the first to explain the principles of how a telescope works.