The familiar cycle of the seasons on Earth is produced by a tilt of what size?

1. Earth spins on an axis that is not upright with respect to its orbit. 2. That axis leans by 23.5 degrees, and it keeps pointing the same way all year. 3. The lean is what swings sunlight between the hemispheres, so it is the cause of the seasons. _Source: OpenStax Astronomy (CC BY 4.0), Ch 4 "Earth, Moon, and Sky" and Ch 5 "Radiation and Spectra", section 4.2 The Seasons_