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    Mercury has been identified as separate from the stars since the time of the ancients.  This planet symbolized the Roman god messenger god (whose Greek name is Hermes).  Since Mercury is the closest planet to the sun, it never gets further than 28 away from the sun, and is normally pretty difficult to see with the unaided eye.  Here are some quick facts about the second smallest planet in our solar system:


Mass -- 3.3 x 1023 kg   (0.055 earth masses)


Radius -- 1,516 mi   (2440 km or 0.3825 earth radii)


Distance from sun (average) -- 35,983,095 mi   (57,909,175 km or 0.3871 AU)


Gravity -- 12.1 ft/sq. sec   (3.7 m/sq. sec)

    An adult weighing 140 lbs on the Earth would only weigh 53 lbs on Mercury.


Maximum surface temperature -- 800 F


Minimum surface temperature -- -280 F (below zero)


Orbital velocity -- 107,088 mph   (172,341 km/hr)


Orbital eccentricity -- 0.2056

    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.


Sidereal rotation -- 1,407.5 hr   (58.646 earth days)

    A day on Mercury is nearly 60x what it is on Earth.


Sidereal orbit -- 2,111.28 hr   (87.97 earth days or 0.241 earth years)

    A year on Mercury is less than 1/4 of an Earth year.


Moons -- none



For more information on Mercury, please visit SEDS' website and NASA's website  Both websites are wonderful resources. 


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