space physics

• Which galaxy is our solar system part of?

  The Milky Way galaxy.
• How many planets make up our solar system?

  Eight (plus the dwarf planets).
• What do the planets in our solar system orbit around?

  The planets orbit around the sun.
• What type of body is the sun?

  The sun is a star.
• What type of force pulled together the cloud of dust and gas to form the Sun?

  Gravitational force of attraction.
• What word is used to describe a cloud of dust and gas?

  A nebula.
• What type of reactions take place at the start of a star’s life cycle?

  Fusion reactions.
• What factor determines the type of lifecycle a star undergoes?

  The size of the star.
• Which two phases do all stars of the same or greater size than the sun undergo?

  Protostar phase and Main sequence phase.
• What do stars of a similar magnitude to the sun become at the end of their life-cycle?

  A black dwarf.
• What two things can stars much bigger than the sun become at the end of their lifecycle?

  Neutron star and Black hole.
• What two phases do stars of similar size to the sun go through between being a main sequence star and a black dwarf?

  Red giant and White dwarf.
• What two phases do stars of greater size than the sun go through between being a main sequence star and a neutron star/black hole?

  Red super giant and Supernova.
• What are produced during the fusion processes in a star?

  All of the naturally occurring elements.
• What condition is required for fusion reactions to occur in a star?

  Very high temperatures.
• How are elements heavier than iron produced?

  In a supernova.
• What type of nuclei fuse together to form heavier elements in a star?

  Hydrogen nuclei fuse to form heavier elements.
• How are elements distributed throughout the universe?

  Through the explosion of a massive star (supernova).
• What allows planets and satellites to maintain circular orbits?

  Gravity provides the gravitational force.
• What type of satellite can a planet’s moon be described as?

  A natural satellite.
• Why must the radius of orbit change if the speed changes for a stable orbit?

  • At higher speeds, greater centripetal force is needed.
  • Increased centripetal force requires a stronger gravitational force.
  • This is achieved by reducing the radius of the orbit.
• How does the force of gravity acting on a satellite affect its speed and velocity?

  • The force alters its velocity due to changing direction.
  • It does not change speed as there's no force component in the direction of motion.
• What is red-shift?

  An observed increase in wavelength of light
• What can be said about the motion and wavelength of emitted light from a galaxy, the further away it is?

  • The further away a galaxy is, the faster it is moving
  • The further away a galaxy is, the greater the observed increase in wavelength
• What does red-shift provide evidence for?

  Evidence that the universe is expanding
• What does the Big Bang theory suggest?

  The universe started from a small, hot region
• 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
• What did scientists observe to provide evidence that the universe is expanding at an ever faster rate?

  They observed supernovae suggesting faster movement
• Prior to observations of supernovae, what was believed about the rate of expansion of the universe?

  • The rate of expansion was expected to occur at an ever slower rate
  • It was thought that gravitational forces would cause this slowing down
• What two ideas could explain the universe’s ever increasing rate of expansion?

  • Existence of dark matter and dark energy
  • These ideas are still being developed and not fully understood