topic 7 - astronomy

• word equation for weight?

  weight = mass x gravitational field strength
• what is the heliocentric model?

  the sun is the centre of the solar system
• what is the geocentric model

  the earth was the centre of the solar system and the sun orbited it
• what is 'retrograde motion'

  • the Earth orbits faster than Mars
  • Earth undertakes some of its moons
  • Evidence that not everything orbited around Earth
• Order of planets from the sun?

  • Mercury, Venus, earth, mars, Jupiter, Saturn, Uranus, Neptune
• why do some planets have rings?

  • gravitational field strength is so strong it attracts debris
• what is the steady state theory?

  • there is a constant density of matter in the universe
  • observable universe is the same at any time of place
• name two pieces of evidence for the big bang theory?

  • Red shift
  • CMBR (cosmic microwave background radiation)
• Why are planets accelerating when orbiting is their speed is constant?

  • they are constantly changing direction
• what is red shift?

  • Wave length appears larger and frequency decreases for galaxies moving away from earth
• what are the 2 star lifecycles?

  • protostar - main sequence star - red giant star - white dwarf- black dwarf
  • prototar - main sequence star- red super giant star - supernova - black hole or neutron star