Astrophysics

• how brightness of a star at standard distance can be represented using absolute magnitude


  apparent magnitude is simply how bright a star appears in the night sky

  brightness of the star depends on its distance from earth and its luminosity

  absolute magnitude is a measure of how bright stars would appear if they were all the same distance from Earth
• Big Bang Theory


  Scientists believe that about 14 billion years ago all matter in the Universe was in one extremely tiny and dense place

  suddenly exploded, and has been expanding ever since

  expansion is shown by the red-shift of galaxies and energy of the explosion can be seen everywhere in Universe as CMBR
• Big Bang Theory - Evidence

  The further away a galaxy is, the greater its red-shift, so it is moving even faster

  This is evidence that the Universe is expanding and so it supports the Big Bang Theory

  microwave radiation can be detected EVERYWHERE in the Universe

  These are the stretched remains of high energy gamma radiation that would have been produced in the explosion that created the Universe.

  They have stretched because the Universe is expanding
• Doppler Effect


  wavelength of the sound will become shorter as it is moving towards you, increasing the frequency, and stretched as it is moving away, decreasing the frequency.
• Red-shift


  The further away a galaxy is the greater its red-shift and hence the faster it is moving away from us
• Why Red-shift is evidence

  More distant galaxies have greater red-shift and therefore are receding faster because the space between all galaxies is stretching as the universe expands
• Redshift example

  e.g. twice the redshift = twice the speed larger speed = larger distance proof for galaxies moving apart / away form each other