Solar system

• Mercury (terrestrial/inner planet)

  • Smallest planet
  • Closest to the sun
  • No moon
  • No atmosphere
• Venus (terrestrial/inner planet)

  • Hottest planet with molten iron core
  • Closest planet to earth
  • No moon
  • Atmosphere: CO2 and H2SO
• Earth (terrestrial/inner)

  • Only planet with life
  • Has one moon
  • Has atmosphere
• Mars (terrestrial/inner)

  • Called the "Red planet" due to iron-rich dust
  • Has two moons
  • Thin atmosphere: CO2
• Terrestrial/inner planet

  • Solid rocky surface
  • Few or no moons
  • Thin atmosphere
• Outer planet

  • Made up of gas/liquid
  • Many moons and/or rings
  • Colder and bigger than inner planets
• Asteroid belt


  Composed of asteroids that separates inner and outer planets
• Asteroids


  Rocks smaller than planets that are made up of nickel and iron
• Jupiter (Outer)

  • Biggest planet
  • Gas giant
  • 50+ moons
  • Atmosphere: hydrogen and helium
• Saturn (outer)

  • Has prominent rings (rocks and ice)
  • Gas giant
  • First observed by Galileo Galilei
• Uranus (Outer)

  • Sideways
  • Has smaller rings than saturn
  • Ice giant
• Neptune (Outer)

  • windiest planet (2000km/hr)
  • Cold (-214°C)
• Milky way


  Galaxy containing our solar system
• Comets


  Dirty snowballs with tails of dusts and gases; tail always points away from the sun

  • Oort cloud; Haley's comet
• Meteor


  Called Meteoroid as it burns up in the atmosphere; shooting star
• Meteorite 


  Incompletely burned meteoroid
• Moon


  Earth's natural satellite
• Black holes


  Collapsed stars due to huge gravitational forces (not even light can escape)
• Quasars

  • Massive and remote celestial object
  • Released very large amount of energy
• Actual motion: how it is
• Apparent motions: how it seems (in the past, people believed that venus moved backwards)
• Force of gravity is directly proportional to mass
• Force of gravity is inversely proportional to distance