mirrored file at http://SaturnianCosmology.Org/ For complete access to all the files of this collection see http://SaturnianCosmology.org/search.php ========================================================== _________________________________________________________________ Mercury Fact Sheet _________________________________________________________________ [1][Global view of Mercury] _________________________________________________________________ Mercury/Earth Comparison _________________________________________________________________ Bulk parameters Mercury Earth Ratio (Mercury/Ear th) Mass (10^24 kg) 0.3302 5.9736 0.0553 Volume (10^10 km^3) 6.083 108.321 0.0562 Equatorial radius (km) 2439.7 6378.1 0.383 Polar radius (km) 2439.7 6356.8 0.384 Volumetric mean radius (km) 2439.7 6371.0 0.383 Ellipticity (Flattening) 0.0000 0.00335 0.000 Mean density (kg/m^3) 5427 5515 0.984 Surface gravity (eq.) (m/s^2) 3.70 9.80 0.378 Surface acceleration (eq.) (m/s^2) 3.70 9.78 0.378 Escape velocity (km/s) 4.3 11.2 0.384 GM (x 10^6 km^3/s^2) 0.02203 0.3986 0.0553 Bond albedo 0.119 0.306 0.389 Visual geometric albedo 0.106 0.367 0.289 Visual magnitude V(1,0) -0.42 -3.86 - Solar irradiance (W/m^2) 9126.6 1367.6 6.673 Black-body temperature (K) 442.5 254.3 1.740 Moment of inertia (I/MR^2) 0.33 0.3308 0.998 J[2] (x 10^-6) 60. 1082.63 0.055 Number of natural satellites 0 1 Planetary ring system No No _________________________________________________________________ Orbital parameters Mercury Earth Ratio (Mercury/Ear th) Semimajor axis (10^6 km) 57.91 149.60 0.387 Sidereal orbit period (days) 87.969 365.256 0.241 Tropical orbit period (days) 87.968 365.242 0.241 Perihelion (10^6 km) 46.00 147.09 0.313 Aphelion (10^6 km) 69.82 152.10 0.459 Synodic period (days) 115.88 - - Mean orbital velocity (km/s) 47.87 29.78 1.607 Max. orbital velocity (km/s) 58.98 30.29 1.947 Min. orbital velocity (km/s) 38.86 29.29 1.327 Orbit inclination (deg) 7.00 0.00 - Orbit eccentricity 0.2056 0.0167 12.311 Sidereal rotation period (hrs) 1407.6 23.9345 58.785 Length of day (hrs) 4222.6 24.0000 175.942 Obliquity to orbit (deg) 0.01 23.45 0.0004 _________________________________________________________________ Mercury Observational Parameters Discoverer: Unknown Discovery Date: Prehistoric Distance from Earth Minimum (10^6 km) 77.3 Maximum (10^6 km) 221.9 Apparent diameter from Earth Maximum (seconds of arc) 13. Minimum (seconds of arc) 4.5 Maximum visual magnitude -1.9 Mean values at inferior conjunction with Earth Distance from Earth (10^6 km) 91.70 Apparent diameter (seconds of arc) 11.0 Mercury Mean Orbital Elements (J2000) Semimajor axis (AU) 0.38709893 Orbital eccentricity 0.20563069 Orbital inclination (deg) 7.00487 Longitude of ascending node (deg) 48.33167 Longitude of perihelion (deg) 77.45645 Mean Longitude (deg) 252.25084 _________________________________________________________________ North Pole of Rotation Right Ascension: 281.01 - 0.003T Declination : 61.45 - 0.005T Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0) T = Julian centuries from reference date _________________________________________________________________ Mercurian Magnetosphere Dipole field strength: 0.0033 gauss-Rh^3 Dipole tilt to rotational axis: 169 degrees Longitude of tilt: 285 degrees (from Mercury I flyby) 115 degrees (from Mercury III flyby) Note: Rh denotes Mercurian radii, 2,439 km _________________________________________________________________ Mercury Atmosphere Surface pressure: ~10^-15 bar (0.001 picobar) Average temperature: 440 K (167 C) (590-725 K, sunward side) Total mass of atmosphere: <~1000 kg Atmospheric composition: 42% Oxygen (O[2]), 29% Sodium (Na), 22% Hydrogen (H[2]), 6% Helium (He), 0.5% Potassium (K), possible trace amounts of Argon (Ar), Carbon Dioxide (CO[2]), Water (H[2]O), Nitrogen (N[2]), Xenon (Xe), Krypton (Kr), Neon (Ne) (The atmosphere of Mercury is essentially a vacuum. Compositional values are not well constrained, values from "Mercury", Vilas, Chapman, and Matthews, eds., University of Arizona Press, 1988) _________________________________________________________________ If no sub- or superscripts appear on this page - for example, if the "Mass" is given in units of "(1024 kg)" - you may want to check the [2]notes on the sub- and superscripts. [3]bullet Notes on the factsheets - definitions of parameters, units, notes on sub- and superscripts, etc. [4]bullet Planetary Fact Table - metric units [5]bullet Planetary Fact Table - U.S. units [6]bullet Planetary Fact Table - Earth ratio _________________________________________________________________ [7]bullet Mercury Home Page [8]bullet Directory to other Planetary Fact Sheets [9]bullet NSSDC Planetary Home Page _________________________________________________________________ [NASA Logo] Author/Curator: Dr. David R. Williams, [10]dwilliam at nssdc.gsfc.nasa.gov NSSDC, Mail Code 633 NASA Goddard Space Flight Center Greenbelt, MD 20771 +1-301-286-1258 _________________________________________________________________ NASA Official: Ed Grayzeck, edwin.j.grayzeck at nasa.gov Last Updated: 27 October 2003, DRW References 1. http://nssdc.gsfc.nasa.gov/planetary/image/mercuryfact_bg.gif 2. http://nssdc.gsfc.nasa.gov/planetary/factsheet/fact_notes.html 3. http://nssdc.gsfc.nasa.gov/planetary/factsheet/fact_notes.html 4. http://nssdc.gsfc.nasa.gov/planetary/factsheet/index.html 5. http://nssdc.gsfc.nasa.gov/planetary/factsheet/planet_table_british.html 6. http://nssdc.gsfc.nasa.gov/planetary/factsheet/planet_table_ratio.html 7. http://nssdc.gsfc.nasa.gov/planetary/planets/mercurypage.html 8. http://nssdc.gsfc.nasa.gov/planetary/planetfact.html 9. http://nssdc.gsfc.nasa.gov/planetary/planetary_home.html 10. mailto:dwilliam at nssdc.gsfc.nasa.gov