Hubble's Law & the Big Bang Theory Edwin Hubble investigated the light spectra emitted from a large number of galaxies He used redshift data to determine the recession velocities of these galax...
Redshift of EM Radiation Recall the Doppler effect is defined as: The apparent change in wavelength or frequency of the radiation from a source due to its relative motion away from or toward the ob...
Emission Spectra Astronomers are very limited in how they can investigate objects in the space All of the techniques used involve analysing the light emitted from the star, or galaxy One of these t...
Stefan-Boltzmann Law A star’s luminosity depends on two factors: Its surface temperature Its radius The relationship between these is known as the Stefan-Boltzmann Law, which states: The total ener...
Wien's Displacement Law Wien’s displacement law relates the observed wavelength of light from a star to its surface temperature, it states: The black body radiation curve for different temperatures...
Standard Candles A standard candle is defined as: An astronomical object which has a known luminosity due to a characteristic quality possessed by that class of object Examples of standard candles ...
Defining Luminosity Luminosity L is defined as: The total power output of radiation emitted by a star It is measured in units of Watts (W) Radiant flux intensity F is defined as: The observed amoun...
Detecting Gamma-Rays from PET Scanning The patient lays stationary in a tube surrounded by a ring of detectors Images of slices of the body can be taken to show the position of the radioactive trac...
The Process of Annihilation When a positron is emitted from a tracer in the body, it travels less than a millimetre before it collides with an electron The positron and the electron will annihilate...
