Space- physics

• The Milky Way galaxy
• Eight (plus the dwarf planets)
• Planets in our solar system orbit around

  • The sun
• Gravitational force of attraction
• Phases stars undergo

  • Protostar phase
  • Main sequence phase
• The sun is a star
• Phases stars of similar size to the sun go through between being a main sequence star and a black dwarf


  • Red giant
  • White dwarf
• During fusion processes in a star, all of the naturally occurring elements are produced
• Stars of a similar magnitude to the sun become a black dwarf at the end of their life-cycle
• Elements heavier than iron are produced in a supernova
• Star life-cycle

  1. Protostar phase

  2. Main sequence phase
• What stars much bigger than the sun can become at the end of their life-cycle

  • Neutron star
  • Black hole
• Hydrogen nuclei fuse to form heavier elements in a star
• Phases stars of greater size than the sun go through between being a main sequence star and a neutron star/black hole


  • Red super giant
  • Supernova
• Very high temperatures are required for fusion reactions to occur in a star
• Artificial satellites


  • TV satellites
  • Satellites used for satellite imaging
• For a stable orbit, the radius of orbit must change if the speed changes

  • At higher speeds, the object requires a greater centripetal force
  • For a greater centripetal force, the gravitational force must increase
  • This is achieved by the radius of the orbit being reduced
• How the force of gravity acting on a satellite affects its speed and velocity

  • The force can alter its velocity since the direction is continually changing
  • It can’t cause a change of speed since there is no force component in the direction of motion
• Planets and satellites maintain circular orbits because gravity provides the gravitational force that acts as the object’s centripetal force and allows for the object to maintain its circular orbit
• Type of nuclei

  • Hydrogen nuclei
• Elements are distributed throughout the universe through the explosion of a massive star (supernova)
• Type of satellite

  • A natural satellite
• Red-shift

  An observed increase in the wavelength of light from distant galaxies
• Red-shift supports the Big Bang theory
• Compare the observed red-shift of two galaxies, one further away than the other

  • The galaxy that is further away is travelling faster
  • The observed red-shift is greater the further away it is
• The further away a galaxy is, the greater the observed increase in wavelength
• Red-shift provides evidence that the universe is expanding
• The further away a galaxy is, the faster it is moving
• The Big Bang theory suggests the entire universe started from a very small, hot and dense region in space
• Scientists observed supernovae to provide evidence that the universe is expanding at an ever faster rate
• It was thought that gravitational forces would cause this slowing down
• Prior to observations of supernovae, the rate of expansion was expected to occur at an ever slower rate
• Ideas explaining the universe’s ever increasing rate of expansion

  • The existence of energy and mass that we can’t detect, known as dark matter and dark energy
  • These ideas are still being developed by scientists and are not yet fully understood
• Comparison of observed red-shift of two galaxies

  • The galaxy that is further away is travelling faster
  • The observed red-shift is greater the further away it is