The Moon has fascinated mankind throughout the ages. One can discern two major types of terrain: relatively bright highlands and darker plains by simply viewing through the naked eye. By the middle of the 17th century, Galileo and other early astronomers made telescopic observations, noting an almost endless overlapping of craters. It has also been known for more than a century that the Moon is less dense than the Earth. Current knowledge of the Moon is greater than for any other solar system object except Earth. This lends to a greater understanding of geologic processes and further appreciation of the complexity of terrestrial planets. Neil Armstrong(July 20, 1969), became the first man to step onto the surface of the Moon. It was being followed by Edwin Aldrin - both of the Apollo 11 mission. They and other moon walkers experienced the effects of no atmosphere. Radio communications were used because sound waves can only be heard by travelling through the medium of air. The lunar sky is always black because diffraction of light requires an atmosphere. The astronauts also experienced gravitational differences. The moon’s gravity is one-sixth that of the Earth’s; a man who weighs 180 lbf (pound-force) on Earth weighs only 30 lbf on the Moon. (The equivalent metric weight (or force) is the Newton, where 4.45 Newtons equal one pound-force.)

• Moon distant from the earth = 384,403 kilometers (238,857 miles)
• diameter = 3,476 kilometers (2,160 miles)
• Both rotation 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. 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.

Moon Statistics

Mass (kg) =========================================== 7.349e+22
Mass (Earth = 1) ====================================== 1.2298e-02
Equatorial radius (km) ================================== 1,737.4
Equatorial radius (Earth = 1) ============================= 2.7241e-01
Mean density (gm/cm^3) =============================== 3.34
Mean distance from Earth (km) =========================== 384,400
Rotational period (days) ================================ 27.32166
Orbital period (days) =================================== 27.32166
Average length of lunar day (days) ======================== 29.53059
Mean orbital velocity (km/sec) ============================ 1.03
Orbital eccentricity ==================================== 0.0549
Tilt of axis (degrees) =================================== 1.5424
Orbital inclination (degrees) ============================== 5.1454
Equatorial surface gravity (m/sec^2) ======================= 1.62
Equatorial escape velocity (km/sec) ======================== 2.38
Visual geometric albedo ================================= 0.12
Magnitude (Vo) ======================================= -12.74
Mean surface temperature (day) =========================== 107°C
Mean surface temperature (night) ========================= -153°C
Maximum surface temperature ============================ 123°C
Minimum surface temperature ============================= -233°C