Hiparco is a prominent figure in ancient astronomy, known for his significant contributions to the field. He lived during the 2nd century BCE and is often regarded as one of the greatest astronomers of antiquity. His work included the development of a star catalog and the introduction of a system to measure the brightness of stars. One of Hiparco's most notable achievements was the discovery of the precession of the equinoxes, a phenomenon that describes the gradual shift in the orientation of Earth's axis. His methods laid the groundwork for future astronomers, influencing figures such as Ptolemy and shaping the study of celestial bodies for centuries.