Astronomy

• There are eight planets in the solar system
• Sun


  A star at the center of the solar system that provides heat and light for the planets
• Planets in order from the Sun

  • Mercury
  • Venus
  • Earth
  • Mars
  • Jupiter
  • Saturn
  • Uranus
  • Neptune
• Satellite


  Something in orbit, can be natural like the Moon or man-made like a camera or telescope
• Asteroids and comets


  Other objects in the solar system
• Geocentric model


  Old model where Earth was at the center and everything orbited around it
• Heliocentric model


  Current model where the Sun is at the center and the planets orbit around it
• Gravity


  A strong force that draws objects towards each other, depends on the size of the objects
• Gravity on Earth is around 10 newtons per kilogram, smaller on the Moon at around 2 newtons per kilogram
• Life cycle of a star

  1. Nebula

  2. Protostar

  3. Main sequence star

  4. Red giant or red supergiant

  5. White dwarf, neutron star or black hole
• Redshift


  Used to show the universe is expanding, as light from objects moving away is shifted to lower frequencies (red)
• Big Bang theory


  Theory that all matter in the universe was once in a small, dense, hot space that then exploded and expanded
• Steady state theory


  Theory that the universe has always existed as it is now, with new matter continuously being created as it expands
• Evidence for the Big Bang theory includes the detection of cosmic microwave background radiation