Space

• name of the galaxy we are in

  Milky Way
• how many planets in our solar system?

  8
• name for a cloud of dust and gas

  nebula
• how does a star form?

  - dust and gas is drawn together by gravity to form a protostar

  - temperature rises as the star gets denser and more particles collide

  - when the temperature is high enough hydrogen nuclei undergo nuclear fusion to form helium nuclei.

  - this gives out energy which keeps the core hot, producing a star
• how does a star reach equilibrium?

  outward energy from fusion balances the inwards force of gravity
• what is the name of a star in equilibrium?

  main sequence star
• describe the lifecycle of stars about the same size as the sun after the main sequence stage

  red giant

  white dwarf

  black dwarf
• describe the lifecycle of stars much bigger than the sun after the main sequence stage

  red super giant

  supernova

  neutron star or black hole
• how are elements heavier than iron produced and spread across the universe?

  in a supernova
• how does fusion lead to new elements?

  in nuclear fusion, two lighter nuclei combine to form a new heavier element
• how does the force of gravity lead to changing velocity but unchanged speed in a circular orbit ?

  the orbiting object is travelling in a circle therfore constantly changing direction meaning that it is always accelerating and changing velocity but not speed.
• why must the radius change if the speed changes in a stable orbit?

  - the closer you get to a planet, the stronger the gravitational force

  - the stronger the force the faster the orbiting object needs to travel to remain in orbit
• do faster moving objects move into orbit with a smaller or larger radius?

  smaller
• do slower moving objects move into orbit with a smaller or larger radius?

  larger
• what keeps a satellite orbiting a planet?

  due to gravity the object keeps accelerating towards the planet, however the instantaneous velocity keeps it travelling in a circle
• what is instantaneous velocity


  velocity of an orbiting object at a right angle to its acceleration
• define red-shift


  - an observed increase in the wavelength of light from most distant galaxies.

  - the further away a galaxy is the faster they are moving and the bigger the observed increase in wavelength
• what does red-shift provide evidence towards

  that the universe is expanding which supports the big bang theory
• what does the big bang theory suggest?

  the universe began from a very small region that was extremely hot and dense
• how is the change of each galaxy's speed with distance is evidence of an expanding universe?

  - the greater the distance from earth, the greater the speed of recession (moving away from earth) .

  - earth has no special place in the universe thus the distant galaxies must be moving away from each other, thus the universe is expanding
• how does red-shift provide evidence for the Big Bang model?

  as the universe expands radiation stretches from high energy to lower energy. scientists have discovered cosmic microwave background radiation which is coming from every direction in space, this can only be explained by the Big Bang theory
• how are scientists are able to use observations to arrive at theories

  such as the Big Bang theory?


  the big bang produced high energy electromagnetic radiation and as the universe expands

  it stretches from high energy to lower energy. scientists have discovered cosmic microwave background radiation which comes from every direction in space. It is low energy thus proving the big bang theory
• what is dark energy ?

  force which causes the accelerating motion of the universe's expansion
• what is dark mass/matter?

  non-luminous material which makes up approximately 80% of the universe's mass