One of the first applications of the knowledge gained from the advance of physics was in the realm of biology. The physiology of the human body could now be understood in terms of its mechanical properties, and during the seventeenth century many of the mysteries of the human body disappeared. However, the most notable application of the laws of physics was in the field of astronomy. Johannes Kepler proved the orbits of the planets were elliptical. Later, Galileo, who in 1630 published his Dialogue on the Two Chief Systems of the World, in which he supported the Copernican, or heliocentric theory of the universe, and denounced the Aristotelian system, which maintained the geocentric theory. Galileo supported his claims with elaborate evidence derived from the study of physics.