Space

• Comets


  Large objects made of dust and ice that orbit the sun

  They have elliptical orbits
• Asteroids


  Large objects made of rock and metal that orbit the sun
• Galaxy


  Collections of billions of stars that all orbit the same point
• Satellite


  An object that orbits a planet
• Planets have elliptical orbits
• Solar system


  Consists of the sun and the objects that orbit it
• Nebula


  Large cloud of dust and gas
• How does a nebula change into a protostar

  Gravity pulls particles of dust and gas together to form a protostar
• Protostar to main sequence star

  Gravity becomes stronger pulling particles together increasing the temperature and pressure

  Nuclear fusion will start fusing hydrogen nuclei together
• Which two forces are in balance in a main sequence star

  Energy released from nuclear fusion creates an outward force that balances against the inward force from gravity
• Which elements undergo nuclear fusion in a main sequence star

  Hydrogen nuclei fuse to make helium nuclei
• How long does a main sequence star last

  Until all the hydrogen is used up
• After a main sequence star

  Red giant (small star)

  Red super giant (large star)
• After red giant 


  White dwarf then a black dwarf as it cools
• What elements can be formed in the red giant phase

  Elements heavier than helium, up to iron
• After red super giant

  Explode in a supernova
• Which elements can be formed in a supernova

  Elements heavier than iron
• After a supernova


  Neutron star (large)

  Black hole (very large)
• Neutron star


  An extremely dense mass of neutrons
• Black hole


  Region where gravity is so strong nothing can escape

  This means no particles, or even electromagnetic radiation such as light, can escape
• Orbit


  The curved path of one celestial object or spacecraft
• Does a planet in orbit around a star have constant velocity?

  It has a constant speed but not a constant velocity since the direction is constantly changes
• What must happen to an orbiting object speed if the radius of its orbit decreases

  Orbital speed must increase
• Are objects in orbit accelerating?

  Yes, objects in orbit are accelerating

  Any change in velocity is considered acceleration
• Red shift


  Wavelengths of light from distant galaxies are higher that expected
• Red shift and the big-bang theory

  Shows the universe is expanding which supports the big-bang theory
• Big bang theory


  Universe expanded from a single tiny point of high density and pressure
• Cosmic microwave background radiation

  Electromagnetic radiation from the Big Bang, now observed in all directions as the universe has expanded and cooled
• Red shift in galaxies

  Suggests galaxies are moving away from us indicating that the universe is expanding
• What does Δλ represent in the equation?

  Change in wavelength (m)
• What does λο represent in the equation?

  Original reference wavelength (m)
• What does v represent in the equation?

  Recessional velocity of the galaxy (m/s)
• What does c represent in the equation?

  Speed of light in a vacuum (300,000,000 m/s)
• What is the speed of light in a vacuum?

  300,000,000 m/s
• What is the equation relating change in wavelength to recessional velocity and speed of light?

  • Δλ/λο=(v / c)
  • Where:
  • Δλ = change in wavelength (m)
  • λο = original reference wavelength (m)
  • v = recessional velocity of the galaxy (m/s)
  • c = speed of light in a vacuum (300,000,000 m/s)
• Steady state theory 


  Suggested that the universe has always existed much as we see it today with a constant density over time
• Steady state theory’s explanation of expansion

  Theory proposed that new galaxies from in the spaces where older ones moved apart keeping the universes density constant