The tilt angle of Earth's spin axis to the direction perpendicular to the ecliptic (known as the ecliptic pole)
A) is 90° and fixed.
B) varies rapidly through the year from +23.5° to -23.5°.
C) is 23.5° and fixed.
D) is 0° and fixed because this defines the ecliptic plane.

Question

Quizplus · Accepted Answer

The tilt angle of Earth's spin axis relative to the direction perpendicular to the ecliptic plane is approximately 23.5° and remains relatively stable over short time periods, such as a human lifetime, though it does change over long geological timescales due to precession and other factors.

The Tilt Angle of Earth's Spin Axis to the Direction