cp.2 THE EARTH AND ITS SYSTEM

• Earth is the third planet from the Sun in our solar system
• Earth appears to be a perfect sphere but is an oblate spheroid, or slightly flattened sphere
• Earth is the only planet that can support life
• Hydrosphere


  Liquid water on Earth that stores heat
• Water absorbs heat during warm periods

  Releases it during cold periods
• Atmosphere


  A mixture of gases that helps to keep Earth’s temperature steady
• Gases in Earth's atmosphere

  • Nitrogen
  • Oxygen
  • Carbon dioxide
  • Water vapor
  • Ozone
  • Other noble gases
• Earth's atmosphere is 78 percent nitrogen, 21 percent oxygen, and 1 percent other ingredients
• The atmosphere protects us from incoming meteoroids, most of which break up in our atmosphere
• Earth is an open system
• Energy radiates into the Earth’s system, mainly from the sun
• Closed system


  The rocks and materials on Earth do not leave the planet in large quantities
• Earth's systems

  • Atmosphere
  • Geosphere
  • Hydrosphere
  • Biosphere
• Troposphere


  The lowest layer of Earth's atmosphere and site of all weather
• The troposphere is bounded on the top by the tropopause and on the bottom by the surface of the Earth
• Stratosphere


  Where airplanes fly and temperature increases with altitude due to ozone
• The ozone layer within the stratosphere absorbs harmful ultraviolet rays of sunlight
• Mesosphere


  The highest layer of the atmosphere in which the gases are all mixed up
• Meteors burn up in the mesosphere
• Thermosphere


  Temperature can reach up to 4,500 degrees Fahrenheit
• The thermosphere is home to the International Space Station and low Earth orbit satellites
• Ionosphere


  An extension of the atmosphere that makes radio waves travel long distances
• Exosphere


  The outermost layer of the atmosphere where atoms and molecules escape into space
• The lithosphere includes the brittle upper portion of the mantle and the crust
• Types of lithosphere

  • Oceanic lithosphere
  • Continental lithosphere
• Types of rocks in the lithosphere

  • Igneous
  • Sedimentary
  • Metamorphic
• Geosphere


  The solid part of the Earth, including rocks, minerals, and the Earth's crust and mantle
• Hydrosphere


  The total amount of water on a planet, including surface, underground, and in the air
• Cryosphere


  The frozen part of Earth's hydrosphere, including glaciers, ice caps, and icebergs
• Biosphere


  The parts of Earth where life exists
• The biosphere has existed for about 3.5 billion years
• Prokaryotes


  The earliest life-forms that survived without oxygen
• The biosphere is sometimes thought of as one large ecosystem