LUNAR IMAGES

The Moon is generally 238,857 miles from the Earth. Its diameter is 2,160 miles. Both the rotation of 
the Moon and its revolution around Earth takes 27 days, 7 hours, and 43 minutes. This 
synchronous rotation is caused by an unsymmetrical distribution of mass in the Moon, which has 
allowed Earth's gravity to keep one lunar hemisphere permanently turned toward Earth. Optical 
librations have been observed telescopically since the mid-17th century. Very small but real 
librations (maximum about 0°.04) are caused by the effect of the Sun's gravity and the eccentricity 
of Earth's orbit, perturbing the Moon's orbit and allowing cyclical preponderances of torque in both east-west and north-south directions