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Comparison of Mercury and Earth

Mercury, the innermost planet in the solar system, is much smaller than Earth, but the material it is made of is much more dense on average. The table below gives a comparison of characteristics of Mercury relative to Earth values.

Characteristic Relative to Earth
(Earth = 1)
Absolute Value
Mass 0.0553 3.303 x 10**26 g
Radius 0.382 2,439 km
Mean Density ----- 5.43 g/cm**3
Rotation Period 58.65 Earth days -----
Mean Orbital
0.3871 AU 57.91 x 10**6 km
Orbital Period 87.9 Earth days -----
Mean Orbital
1.6 47.89 km/s
(112,000 mi/hr)
Orbital eccentricity ----- 0.2056
Inclination to
ecliptic (degrees)
----- 7.004
Temperature range ----- -360F (-183C) to
840F (450C)

Definitions of planetary characteristics

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA