Which is because the earths axial tilt is that angle: Earth's mean obliquity is currently 23°26′12.2″ (or 23.43672°) and decreasing. https://en.wikipedia.org/

Which is because the earths axial tilt is that angle: Earth's mean obliquity is currently 23°26′12.2″ (or 23.43672°) and decreasing. https://en.wikipedia.org/wiki/Axial_tilt https://en.wikipedia.org/wiki/Axial_tilt