Stars and planets

• Example of a Galaxy

  The Milky Way
• Our solar system is located in the Milky Way galaxy
• Planets in our solar system

  Eight (plus the dwarf planets)
• What the planets orbit around

  The sun
• Type of body the sun is

  A star
• Force that pulled together the cloud of dust and gas to form the sun

  Gravitational force of attraction
• Cloud of dust and gas

  A nebula
• Reactions that take place at the start of a star's life cycle

  Fusion reactions
• Factor that determines the type of lifecycle a star undergoes

  The size (and therefore mass) of the star
• Phases all stars of the same or greater size than the sun undergo

  • Protostar phase
  • Main sequence phase
• What stars like the sun become at the end of their life-cycle

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

  • Neutron star
  • Black hole
• Phases stars like the sun experience between being a main sequence star and a black dwarf


  • Red giant
  • White dwarf
• Phases stars of greater size than the sun go through between being a main sequence star and a neutron star/black hole


  • Red supergiant
  • Supernova
• What is produced during the fusion processes in a star

  Atoms of all of the naturally occurring elements
• Condition required for fusion reactions to occur in a star

  Very high temperatures and pressures
• Where elements heavier than iron are produced

  In a supernova
• Type of nuclei that fuse together to form heavier elements in a star

  Hydrogen nuclei fuse to form heavier elements
• How elements are 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 that acts as the object's centripetal force. The presence of a centripetal force allows for the object to maintain its circular orbit.
• Type of satellite a planet's moon can be described as

  A natural satellite
• Artificial satellites


  • TV satellites
  • Satellites used for satellite imaging
• Type of planet Pluto is classed as

  A dwarf planet
• Description of a comet

  A high speed ball of ice and rock which as it melts leaves a trail of dust and gas behind it
• Term given to the four outer planets of our solar system

  Gas giants
• What a light year is a unit of


  Distance, used for the distances between the Earth and stars and other galaxies
• Unit of measurement used to measure distances between the sun and planets

  The Astronomical Unit (AU)
• Colour of the hottest stars

  Blue stars are the hottest stars, red stars are the cooler stars
• What a Hertzsprung-Russell diagram shows

  The luminosity of stars against their temperature