Earth

Photo by Apollo 16 astronauts on the way to the Moon.  April 1972.

"Earth is the cradle of man, but man does not live in the cradle forever."

          -- Konstantin Tsiolkovsky


Orbital Elements
Mean distance from Sun149,597,870 km    =    1 astronomical unit
Perihelion distance147,090,000 km=    0.9832 astronomical unit
Aphelion distance152,100,000 km=    1.0167 astronomical units
Eccentricity of orbit0.0167
Period of orbit365.25636 days=    365:06:09:10    =    31,558,150 seconds
Mean orbital speed29.79 km/s
Minimum orbital speed29.29 km/s
Maximum orbital speed30.29 km/s
 
Physical Properties
Mean diameter12,742 km
Polar radius6,356.755 km
Equatorial radius6,378.140 km
Oblateness1/298
Mass5.97223 x 1024 kg
Mean density5.515 g/cm3
Rotational period0.997269 day=    23.9345 hours    =    23:56:04    =    86,164 s
Mean length of day24 hours=    86,400 s
Inclination of axis23.45relative to the axis of its orbit
Gravity at surface9.78 m/s2
Escape speed11.2 km/sfrom surface, at equator
Visual geometric albedo0.37
Mean surface temperature    15C
Atmospheric pressure1 bar
 
Atmosphere   composition by volume
Nitrogen (N2)78%
Oxygen (O2)21%
Argon (Ar)0.93%
Carbon dioxide (CO2)0.03%
Neon (Ne)0.0018%
Helium (He)0.00052%
Methane (CH4)0.0002%
Krypton (Kr)0.00011%
Hydrogen (H2)0.00005%
Xenon (Xe)0.0000087%
Plus highly variable amounts of water.
 
Composition of the Earth as a whole   by mass
Iron (Fe)34.6%
Oxygen (O)29.5%
Silicon (Si)15.2%
Magnesium (Mg)12.7%
Nickel (Ni)2.4%
Sulfur (S)1.9%
Titanium (Ti)0.05%

Moon

One large moon.


HomeTo my Space and Science home page  for more about the Solar System

Jeff Root
September 4, 2003