Earth (planet)


The Earth is the third planet from the Sun in the Solar System.  As a planet, it took a while before it was even realised it was even a planet or it's relationship to the solar system. For the humans on it it took quite some clever thinking to realise where it was.


View of the Earth from the International Space Station. Hurricane Ike. image: NASA

Orbit basics:

  • Distance from sun: between 147,098,291 and 152,098,233  km (the average is called 1 AU (astronomical unit)
  • Orbital period (it's year):  365.26 Earth days
  • Moons (natural satellite):

Planet basics:

  • Type of planet: The original rocky/terrestrial
  • Length of day: 23.934 hours
  • Average radius: 6,371.00 km
  • Mass: 5.9722 x 1024 kg
  • Surface gravity: 1 g or 9.80665 m/s2
  • Escape velocity: 11.186 km/s (40,270 km/h)
  • Mean density: 5.515 g/cm3
  • Surface temperature: min of−89.2 °C average of 14 °C maximum of 57.8 °C
  • Atmosphere: Substantial enough
  • Pressure: 1 bar or 101.325 kPa (Mean Sea Level)
  • Atmospheric composition: 
    • 78.08% nitrogen (N2) (dry air)
    • 20.95% oxygen (O2)
    • 0.93% argon
    • 0.038% carbon dioxide
    • About 1% water vapor (varies with climate)
    • wide range other chemical traces, such as NOx(nitrous oxides), SO (sulphur oxides), O3 ozone (safer and essential in the ozone layer, but a health hazard at lower altitudes)