Astronomy’s purpose in early times was mainly perceiving the length of the year, to predict the seasons and the factors that influence how crops will be planted and harvested. Before any tools for astronomical observation were invented, this science referred only to the observation and predictions visible with the naked eye.
The field of science now called astrometry, referred to the scientific observations linked to the mapping and positioning of planets and stars, led by some of the notable civilisations that took part in the development of this science, such as Mesopotamian, Greek, Indian, Chinese, Egyptian and Mayan. These observations led to the first ideas about motion of the Sun, the Moon and the stars that rotate around it. The Ptolemaic system is one of the first geocentric models of the universe.
The Babylonians were the first to observe the recurrent cycle behind the lunar eclipses. They named it saros. The Greek followed with logical explanations for these phenomena visible on the sky. Aristarcus of Samos was the first to estimate the distance between the Moon and the Sun, their sizes and the heliocentric model of our solar system, in the 3rd century. The astrolabe, a device that calculated the size of the moon was the invention of Hipparchus in the 2nd century. He also observed and created a catalog of 1020 stars. In the 9th century, a Persian astronomer called Azophi was the first to discover and describe the Andromeda Galaxy. Also, the brightest stellar event, a supernova called SN1006 was first observed by the Chinese astronomers and Ali ibn Ridwan, an Egyptian Arabic astronomer, in 1006.
Significant inventions were not made until the 14th century, when Europe started to build the first astronomical clocks. During the Enlightenment period, the Roman Catholic Church gave financial and social support to astronomy research, with the intention to find the Easter date.