Topic 8

• What causes objects to orbit other objects?

  Gravity
• How does gravity act in an orbit?

  It acts towards the centre of the orbit
• What happens to the speed of objects in circular orbits?

  They move at the same speed, but velocity changes
• What occurs if the orbital radius decreases?

  Gravitational attraction increases
• What is required for a stable orbit?

  Orbital speed must increase
• Is Pluto considered a planet in the Solar System?

  No, it is not
• Where does the Asteroid Belt lie?

  Between Mars and Jupiter
• What do stars fuse elements up to?

  Iron
• What are the inner planets mostly made of?

  Rock
• What are the outer planets mostly made of?

  Gas
• How many planets are in our solar system?

  Eight
• In which galaxy is our solar system located?

  Milky Way Galaxy
• What does it mean that the Solar System is heliocentric?

  The planets orbit the sun
• Where do dwarf planets orbit?

  In the outer reaches of the Solar System
• What is the mnemonic for remembering the order of planets?

  • My Very Easy Method Just Speeds Up Naming
  • Planets in order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune (Pluto)
• What happens to light from a distant object moving away from Earth?

  It appears more red
• What does a greater red-shift indicate?

  Objects are moving away faster
• How is red-shift related to the Big Bang Theory?

  It provides evidence for the theory
• What is CMBR?

  Cosmic Microwave Background Radiation
• What elements do stars fuse up to?

  Iron
• What does red-shift provide evidence for?

  The expansion of the universe
• How are elements heavier than iron formed?

  In a supernova
• What are the stages in the life cycle of a star?

  1. Nebula (cloud of gas and dust)
  2. Protostar
  3. Main Sequence Star
  4. Red Giant or Red Supergiant
  5. Supernova
  6. White Dwarf or Neutron Star or Black Dwarf

  
• What is a nebula?

  A cloud of gas and dust
• What is a protostar?

  Early stage of a star's formation
• What is a black dwarf?

  Final stage of a white dwarf
• What is a white dwarf?

  Remnant of a small, sun-like star
• What is a red supergiant?

  A large star before a supernova
• What is a neutron star?

  Remnant of a large star after a supernova