The Babylonians adopted a more scientific approach to astronomy than their Sumerian forebears, though religion and astronomy were still intertwined. For example, the Sun, the Moon and the five known planets were closely identified with the principal gods of the Babylonian pantheon – Jupiter with Marduk, Venus with Ishtar and so on. However, rather than simply watching the motions of the heavenly bodies, Babylonian astronomers sought to understand them, to enable predictions of their positions in the future.
Through painstaking observations, the Babylonians were the first to recognize that astronomical events occur in cycles. This enabled them to develop a calendar, based on both their own findings and an earlier calendar devised by the Sumerians. Knowing the dates of the seasons was of vital importance for agriculture, allowing farmers to plant their crops at optimal times to feed the burgeoning population. Babylonians measured time using sundials and water clocks. Although none of these instruments has survived to the present day, we know of their existence from clay tablets describing the rising and setting of the Sun, Moon and planets.
The Enuma Anu Enlil is a series of around 70 tablets recording celestial motions, the phases of the Moon, lunar and solar eclipses, and weather phenomena spanning centuries. It includes the Venus Tablet of Ammisaduqa, which was compiled during the 17th century BCE and details the times of the first and last risings of the planet Venus over two decades. However, much of the content of these tablets is concerned with divination and omens, aiming to interpret the astronomers’ observations in terms of the fortunes of the king and his empire. Astronomy in Babylonian times was very much a branch of astrology.
In the 12th century BCE, Babylonian astronomers began to compile “star catalogs" – lists of the visible stars, grouped into constellations. Many had Sumerian names, demonstrating the continued influence of Sumerian astronomy in Babylon. Some of the constellations identified by the Babylonians – including Taurus, Leo, Scorpio, Capricorn, Gemini and Cancer – are still recognized by astronomers and astrologers today.