Which Greek thinker developed the astrolabe for celestial observations?

The development of the astrolabe for celestial observations is attributed to Hipparchus, a notable Greek astronomer and mathematician who lived during the 2nd century BCE. Hipparchus is known for his contributions to observational astronomy and is considered one of the greatest astronomers of antiquity. The astrolabe, a sophisticated instrument used for solving problems related to time and the position of the stars and planets, was a crucial tool in both astronomy and navigation.

Hipparchus also made significant advancements in mapping the heavens, including the creation of star catalogs and his introduction of trigonometry into astronomy. His work laid the foundation for subsequent studies in astronomy and the development of more refined instruments for celestial observations.

The other thinkers mentioned contributed to various fields but did not develop the astrolabe. Eratosthenes is famous for calculating the Earth's circumference, Aristarchus is known for his heliocentric theory, and Democritus is associated with atomic theory. Each made important contributions but is not linked to the creation of the astrolabe.