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Solar System Exploration
Earth: Overview
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Color image showing the full disk of Earth.
A true-color NASA satellite mosaic of Earth.

Earth, our home planet, is the only planet in our solar system known to harbor life - life that is incredibly diverse. All the things we need to survive exist under a thin layer of atmosphere that separates us from the cold, airless void of space.

10 Need-to-Know Things About Earth:

  1. If the sun were as tall as a typical front door, Earth would be the size of a nickel.
  2. Earth is the third planet from the sun at a distance of about 150 million km (93 million miles) or one AU.
    Color image of spacecraft orbiting Earth.
    Spacecraft study Earth from above.
  3. One day on Earth takes 24 hours (this is the time it takes the Earth to rotate or spin once). Earth makes a complete orbit around the sun (a year in Earth time) in about 365 days.
  4. Earth is a rocky planet, also known as a terrestrial planet, with a solid and dynamic surface of mountains, valleys, canyons, plains and so much more. What makes Earth different from the other terrestrial planets is that it is also an ocean planet: 70 percent of the Earth's surface is covered in oceans.
  5. The Earth's atmosphere is made up of 78 percent nitrogen (N2), 21 percent oxygen (O2) and 1 percent other ingredients -- the perfect balance for us to breathe and live. Many planets have atmospheres, but only Earth's is breathable.
  6. Earth has one moon. Another name for a moon is satellite.
  7. Earth has no rings.
  8. Many orbiting spacecraft study the Earth from above as a whole system and together aid in understanding our home planet.
  9. Earth is the perfect place for life.
  10. Earth's atmosphere protects us from incoming meteoroids, most of which break up in our atmosphere before they can strike the surface as meteorites.

Read More About Earth Blue arrow

Homework? We can help. Link to Earth homework helper.
Just the Facts
Orbit Size (semi-major axis):  149,598,262 km
Mean Radius:  6,371.00 km
Volume:  1,083,206,916,846 km3
Mass:  5,972,190,000,000,000,000,000,000 kg
23 Sep 2015: 
22 Dec 2015: 
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Last Updated: 28 Apr 2014