66½°
Explanation
The Earth rotates on its axis while revolving around the Sun. The axis of rotation is not perpendicular to the plane of its orbit (the ecliptic plane). This inclination is a fundamental factor affecting the distribution of insolation and the occurrence of seasons.
Analysis:
- The Earth's axis is tilted at an angle of 23½° from the line perpendicular to the orbital plane.
- Consequently, the angle that the Earth's axis makes with the orbital plane itself is calculated by subtracting the tilt from the perpendicular (90°).
- Calculation: 90° - 23½° = 66½°.
Key Takeaway:
It is crucial to distinguish between the angle of inclination from the vertical (23½°) and the angle made with the orbital plane (66½°).