Why was Johannes Kepler important to modern astronomy?
German astronomer Johannes Kepler (1571–1630) devised three mathematical statements that accurately describe the rules for planetary revolutions around the Sun. (An astronomer is a scientist who specializes in the study of matter in outer space.) The first and most important rule states that the shape of any planet’s orbit (path) is an ellipse (oval). This contradicted the theory of Polish astronomer Nicholas Copernicus (1473–1543; also known as Mikolaj Kopernik), who believed that planetary orbits were circular. The second rule describes the speed at which a planet makes its orbit, based on its distance from the Sun. This implies that if an imaginary line were to be drawn between the Sun and the planet, the line formed would sweep out in areas of space like pie slices and that the area swept out in equal periods of time is the same at all…
