The understanding that the Sun has various sunset points, which change throughout the year, is attributed to ancient civilizations and their observations of celestial phenomena. The specific individual who made the first observation of this nature is difficult to pinpoint due to the antiquity of the knowledge.
Ancient civilizations, such as the Babylonians, Egyptians, and Greeks, had sophisticated astronomical observations and tracking systems. They noticed the changing positions of the sunrise and sunset points throughout the year, leading to the development of calendars and the recognition of seasons.
One notable figure in ancient astronomy is the Greek philosopher and astronomer, Claudius Ptolemy (c. 100–170 AD). Ptolemy's work, including his influential book "Almagest," documented and explained the apparent motion of celestial bodies, including the Sun. He provided detailed mathematical models for predicting the positions of the Sun, Moon, and planets, which contributed to our understanding of their movements and the changing points of sunrise and sunset.
However, it is essential to recognize that the knowledge of the Sun's changing sunset points predates Ptolemy. Ancient cultures worldwide had their own systems for observing and recording celestial events, which contributed to our collective understanding of astronomical phenomena.