The phenomenon of precession of Earth's spin axis is caused by the:
A) variation of Earth's spin rate.
B) tidal ebb and flow of ocean waters on Earth.
C) varying intensity and hence pressure of sunlight on Earth throughout the year.
D) gravitational pull of Moon and Sun on Earth's equatorial bulge.

Question

Quizplus · Accepted Answer

The gravitational pull of the Moon and Sun on Earth's equatorial bulge causes a torque that causes the precession of Earth's spin axis. This is known as the "precession of the equinoxes" and takes approximately 26,000 years to complete one cycle. The other options do not accurately explain the cause of this phenomenon.

The Phenomenon of Precession of Earth's Spin Axis Is Caused