The term for the tilt of the Earth's axis is known as axial tilt or obliquity. This tilt, approximately 23.5 degrees, is responsible for the changing seasons as the Earth orbits the sun. Variations in axial tilt can affect climate patterns over long periods, influencing factors such as temperature and day length. Understanding axial tilt is crucial in the fields of astronomy and climatology, as it plays a significant role in Earth's climate systems and seasonal changes.