year 12

• what is the Solar System?

  a star we call the Sun, the 8 planets orbiting it, moons, asteroids and comets
• name the planets in order from the closest to the Sun outward.

  Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
• name the four rocky "inner planets"

  Mercury, Venus, Earth, Mars
• name the four gas "outer planets"

  Jupiter, Saturn, Uranus, Neptune
• What is a satellite?

  an object that is orbiting another object
• what is gravity?

  the force of attraction between any two masses
• what force keeps a planet/comet/asteroid orbiting a star like the sun

  gravity
• what force keeps a satellite orbiting a planet like earth?

  gravity
• give an example of a natural satellite of the earth

  the moon
• give four uses of artificial satellites

  • observing the earth
  • weather monitoring
  • astronomy
  • communication
• How do stars form?

  A cloud of dust and gas (called a nebula) is pulled in by its own gravity
• What process powers a star?

  Nuclear Fusion of Hydrogen to Helium
• What is the 'Hydrogen fusing to Helium' part of a star's life called?

  Main sequence
• What are the stages of the life cycle of a lower mass star like our sun?

  • Protostar
  • Main Sequence
  • Red Giant
  • White Dwarf
  • Black Dwarf
• What are the stages of the life cycle of a higher mass star?

  • Protostar
  • Main Sequence
  • Red Supergiant
  • Supernova
  • Neutron Star or Black Hole
• What is a supernova?

  A massive explosion throwing out outer layers and shining as brightly as 10 billion suns for a short time
• What is a black hole?

  Neutron stars with extreme gravity
• Why are black holes black?

  Nothing can escape their strong gravity
• What is The Big Bang Theory?

  A model explaining the Universe's origin
• What do we mean by the Universe?

  Everything that exists everywhere

  All the matter and all the energy
• Describe the Big Bang sequence up to the formation of Hydrogen.

  Expansion and cooling allows neutrons and protons to form.

  Further cooling allows electrons to combine with nuclei to form simple atoms of hydrogen
• How do we know what elements are present in the sun?

  Dark lines in the spectrum indicate elements
• How did astronomers discover that distant galaxies were moving away?

  Dark lines in their spectrum have longer wavelengths
• What is Red Shift when we look at distant galaxies?

  Spectral lines are shifted towards the red end of the spectrum and the wavelengths have been made longer
• What does the red shift of distant galaxies mean about their motion?

  They are moving away from us
• What does the discovery of red shift mean about the Universe?

  The Universe must be expanding
• What other piece of evidence supports the Big Bang Theory?

  Cosmic Microwave Background Radiation (CMBR)
• What is an Exoplanet?

  A planet outside our solar system
• What happens when a planet is discovered by the transit method?

  The planet dims the star's light temporarily
• What happens when a planet is discovered by the radial velocity method?

  Movement causes variations in the star's light spectrum
• What discovery might indicate the possibility of life on another planet?

  Finding oxygen in the atmosphere
• What is the name of our closest star after the sun, and how far away is it?

  Proxima Centauri, about 4 light years away
• What is a light year?

  The distance light travels in one year
• If light travels at $3 \times 10^8 \text{ m/s}$ and a year is 365 days, how do you calculate the number of metres in a light year?


  $3 \times 10^8 \times 60 \times 60 \times 24 \times 365$
• What prevents us from sending humans to the nearest star outside our solar system?

  It would take thousands of years to reach
• What do all waves carry and how is it transferred?

  All waves carry energy through vibrations
• Define a transverse wave.

  Particle vibration is perpendicular to the direction of travel
• Define a longitudinal wave.

  Particle vibration is parallel to the direction of travel
• Give two examples of transverse waves.

  • Surface water waves
  • Electromagnetic waves (e.g., radio, light)
• Give two examples of longitudinal waves.

  • Sound waves
  • Ultrasound waves