earth and space

• what is red shift?

  when a light source moves away from you, the wavelength of the light that it emits increases and the frequency decreases.
• if the source is moving faster the red shift is?

  bigger
• if the source is moving away from you, the light is?

  blue-shifted
• if the light is blue shifted what happens to the wavelength and frequency?

  wavelength decreases and frequency increases
• the more distance a galaxy is, the ______ it is moving away

  faster
• the big bang model:

  • the movement of galaxies provides evidence for an expanding universe
  • the universe started from something extremely dense and smaller than the size of an atom which is expanded suddenly
• what is the other evidence for the big bang model?

  Cosmic microwave background radiation (CMBR)

  • this is radiation left over from the big bang
  • the very high energy radiation and high frequency has been stretched over time
• what is in the solar system?

  the sun, planets, moons, minor planets, comets
• what are the four inner planets?

  mercury, Venus, earth and mars
• what are the four outer planets?

  jupiter, saturn, uranus and neptune
• what is another word for jupiter and saturn

  gas giants
• what is another worse for uranus and neptune?

  ice giants
• what is the area between mars and jupiter?

  the asteroid belt
• what dwarf planet is in the asteroid belt?

  ceres
• how was the sun formed?

  1. made of huge clouds of dust and hydrogen gas
  2. gravity pulled gas and dust together
  3. the central core got very hot
  4. particles were moving fast enough for nuclear fusion to start
• what state are stars like sun in?

  equilibrium
• what type of star is the sun?

  a main sequence star
• what will be the cycle of our sun?

  it will eventually become a white dwarf - this is because the hydrogen is used up, so fusion slows down and the core cools down.

  the star becomes a red giant - this is because gravity pulls the outer layers inwards and the core heats up
• natural satellites

  the moons around planets in the solar system

  • they are made of the same material as the rest of the objects in the solar system
• how long does a geostationary orbit take for one orbit?

  24 hours
• how long does a low polar orbit take for one orbit?

  approximately 2 hours
• what are the uses of geostationary orbits?

  communications

  satellite television
• what are the uses of low polar orbits?

  military (spying)

  observation of earth

  weather
• where do geostationary orbits orbit?

  in a fixed position above the equator
• where do low polar orbits orbit?

  over the poles
• why are orbits circular?

  the gravitational force that acts on the object in orbit acts toward the centre of the planet. this is at right angles to its velocity. the force changes the direction of motion, so it is accelerating, even though its speed does not change.
• what does the radiation that an object emits depend on?

  temperature