Earth

Introduction

 

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.

Image description

10 Need-to-Know Things About Earth:

  • If the sun were as tall as a typical front door, Earth would be the size of a nickel.
  • Earth is the third planet from the sun at a distance of about 150 million km (93 million miles) or one AU.
  • 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.
  • 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.
  • 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.
  • Earth has one moon. Another name for a moon is satellite.
  • Earth has no rings.
  • Many orbiting spacecraft study the Earth from above as a whole system and together aid in understanding our home planet.
  • Earth is the perfect place for life.
  • Earth's atmosphere protects us from incoming meteoroids, most of which break up in our atmosphere before they can strike the surface as meteorites.

Earth's Moon

Our moon makes Earth a more livable planet by moderating our home planet's wobble on its axis, leading to a relatively stable climate, and creating a tidal rhythm that has guided humans for thousands of years. The moon was likely formed after a Mars-sized body collided with Earth and the debris formed into the most prominent feature in our night sky.

Image description

10 Need-to-Know Things About Earth's Moon:

  • If the sun were as tall as a typical front door, Earth would be the size of a nickel and the moon would the size of a green pea.
  • The moon is Earth's satellite and orbits the Earth at a distance of about 384 thousand km (239 thousand miles) or 0.00257 AU.
  • The moon makes a complete orbit around Earth in 27 Earth days and rotates or spins at that same rate, or in that same amount of time. This causes the moon to keep the same side or face towards Earth during the course of its orbit.
  • The moon is a rocky, solid-surface body, with much of its surface cratered and pitted from impacts.
  • The moon has a very thin and tenuous (weak) atmosphere, called an exosphere.
  • The moon has no moons.
  • The moon has no rings.
  • More than 100 spacecraft been launched to explore the moon. It is the only celestial a body beyond Earth that has been visited by human beings (The Apollo Program).
  • The moon's weak atmosphere and its lack of liquid water cannot support life as we know it.
  • Surface features that create the face known as the "Man in the moon" are impact basins on the moon that are filled with dark basalt rocks.