In general Babylonian astronomy focused on the behavior and trajectory of the moon, rather than the planets. Unlike the later Greek astronomers, who were concerned with geometrically describing the paths of the planets (Neugebauer pg. 279), the Babylonians concentrated on recording periodic phenomena the planets observed such as period of motion, times of first visibility, times when the planet changed directions relative to the earth, and times of opposition with the sun (idem). In this sense the procedures for measuring planetary phenomena and the format in which the data concerning them were written down resembled those for the moon.

Because the planets all approximately lie on the ecliptic plane, latitude was generally not important in measurements. However because they orbit around the sun, rather than earth, at varying speeds, their motion is much more complicated than the moon's. Most notable are the turning points at which the planets change their direction for a period of time (called the regression period) from eastward to westward, after which they resume their eastward movement.

The Babylonians observed that the motion of the planets was periodic, and hence so were the planetary phenomena they wished to record. They therefore were interested in determining the length of these periods, which could be used to predict future occurrences.