Space

• What is the astronomical unit

  The astronomical unit is the mean distance between the Earth and the Sun

  1AU = 1.5x10^11
• What is a light year

  The distance through space that a light photon travels in the space of a year

  1ly = 9.46x10^15
• What can parallax be used for

  Parallax can be used to calculate distances in space using observations and triganometry
• What is a parsec

  A parsec is an astronomical unit of distance. A star is one parsec away from the Earth if the parallax angle is 1 arcsecond
• What is a Hertzsprung-Russel diagram

  A Hertzsprung-Russell diagram is a plot of a stars stellar luminosity against its surface temperature
• What is the doppler effect

  The doppler effect is the apparent change of wavelength as a result of relative movement between a receiver and source
• What is red shift

  Red shift is the apparent shift of the wavelength of light emitted by a star towards the red end of the light spectrum as a result of its receding
• What is the difference between a positive and negative z value

  A positive z value represents red shift where as a negative value represents blue shift
• What are the two main conclusions that can be drawn from observations of red shift from distant galaxies

  1. All galaxies show red shift and so all galaxies are moving away
  2. The more distant a galaxy is the greater its red shift and so the faster it is receding
• What does the red-shift of distant galaxies provide evidence for

  Red-shift of distant galaxies suggests that they are moving away from us. This supports the concept that the universe is expanding which supports the Big Bang theory
• What is cosmic microwave background radiation

  Radiation in the microwave region of the EM spectrum that is present in very small quantities all around us
• How does the existence of the CMBR support the Big Bang theory

  In the big bang, lots of high energy radiation was produced. As the universe has expanded over time the wavelength of this radiation has been stretched so that it is now in the microwave region. Other theories of the universe cant account for the existence of the CMBR
• What is the Big Bang theory

  The big bang theory is a theory for the formation of the universe, it proposes that the universe began from a very small, hot and dense region and expanded from this point
• Hubbles law

  The speed at which a galaxy is moving away is directly proportional to the distance it is at
• Standard candle

  A stellar object with a known luminosity
• What are the two types of standard candles?

  • Cepheid variables
  • Type 1a supernovae
• Intensity

  Power per unit area