Kiwanis Chico Community Observatory







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Lunar Facts


    The ancients were fascinated by the moon.  Cultures all over the world kept track of time with the phases of the moon, and many had ceremonies based on its progression.  Today there are many misconceptions about the moon.  The moon is NOT visible every night.  It is NOT made of cheese.  There is no "dark side of the moon".  Here are some other fun facts about the moon:


Mass -- 7.35 x 1022 kg   (0.012 earth masses)


Radius -- 1079 mi   (1738 km or 0.272 earth radii)

    A radius is the distance from the center of a circle / sphere to the edge.  The moon's diameter (two radii) is slightly smaller than the distance across the continental US.


Distance from Earth (average) -- 238,900 mi   (384,400 km)

    If there were a road to the moon, it would take you about half a year to drive there (at 60 mph).


Gravity -- 5.322 ft/sq. sec   (1.622 m/sq. sec)

    An adult weighing 140 lbs on Earth would only weigh 23 lbs on the moon.


Average daytime temperature -- 225 F


Average nighttime temperature -- -243 F    (below zero)


Orbital velocity -- 2,288 mph   (3,683 km/hr or 0.034 earth speed)


Orbital eccentricity -- 0.055

    This is how off-circular the moon's orbit around the Earth is.  An eccentricity of 0.00 would be a perfect circle.  An eccentricity of nearly 1 would be a very flattened oval.  For a fun project on ellipses and eccentricity, click here.


Tilt of orbit -- 5.15

    Because of this tilt (as compared to the Earth's orbit around the sun), eclipses do not occur at every new and full moon.


Lunar month -- 29.5 days

    This is the time it takes for the moon to complete one phase cycle.  For example, the time the moon takes to go from new moon back to new moon again.


Sidereal revolution period -- 27.3 days

    This is the time it takes for the moon to completely orbit around the Earth.  For example, the time the moon takes to start in the constellation Virgo and come back to Virgo again.


Sidereal rotation period -- 27.3 days

    Because the sidereal revolution period = the sidereal rotation period, we always see the same side of the moon from Earth.  The moon is "tidal locked" in its orbit.



*Information from Discovering the Universe (Comins, Kaufmann) and


Our Sun

Our Moon

Solar System

Deep Sky Objects




Website last updated March 16,  2006.  Hosted by Anthony Watts, KMXI Radio.  Webmasters Tiara Norris and Brendan Diamond.