The "orbital period" is the time it takes for an object to complete one full orbit around another object. For example, the Earth has an orbital period of about 365.25 days as it revolves around the Sun. This period can vary significantly depending on the distance between the two objects and their masses. Different celestial bodies have different orbital periods. For instance, Mars takes about 687 Earth days to orbit the Sun, while Mercury completes its orbit in just 88 Earth days. Understanding orbital periods helps scientists study the movements of planets, moons, and other celestial objects in space.