The Moon is 384,403 kilometers (238,857 miles) distant from the Earth. Its diameter is 3,476 kilometers
(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.
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Moon Statistics
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Mass
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7.349e+22 kg
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Mass (Earth = 1)
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1.2298e-02
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Equatorial radius
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1,737.4 km
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Mean density
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3.34 (gm/cm³)
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Mean distance from Earth
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384,400 km
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Rotational period
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27.32166 days
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Orbital period
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27.32166 days
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Average length of lunar day
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29.5305 days
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Mean orbital velocity
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1.03 km/sec
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Orbital eccentricity
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0.0549
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Tilt of axis
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1.5424 degrees
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Orbital inclination
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5.1454 degrees
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Equatorial surface gravity
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1.62 m/sec²
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Equatorial escape velocity
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2.38 km/sec
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Visual geometric albedo
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0.12
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Magnitude
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-12.74 Vo
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Mean surface temperature
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107° C Day
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Mean surface temperature
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-153° C Night
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Maximum surface temperature
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123° C
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Minimum surface temperature
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-233° C
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