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Earth

Earth is the third planet from the Sun and the only known astronomical object to harbour life. Its liquid water, oxygen-rich atmosphere, and magnetic field create the perfect conditions for life. About 71% of its surface is covered by water - giving it the nickname "the Blue Marble".

Overview

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Atmosphere composition

Nitrogen 78.1%
Oxygen 20.9%
Argon 0.93%
Carbon Dioxide 0.04%
Other 0.03%

Notable features

  • Only known planet with confirmed life
  • Plate tectonics - active geological reshaping
  • Large Moon - stabilises Earth's axial tilt
  • Magnetosphere - shields surface from solar wind
  • Liquid water oceans covering 71% of the surface
  • Ozone layer protecting life from UV radiation

Space missions

Mission Year Notes
Sputnik 1 1957 First artificial satellite to orbit Earth
Apollo 8 1968 First crewed mission to leave Earth orbit
Landsat 1 1972-present Continuous Earth observation from orbit
ISS 1998-present Permanent human presence in low Earth orbit
Sentinel 2014-present ESA Copernicus Earth observation constellation

NASA images

Images courtesy of NASA Image & Video Library.