Space

• Star


  Formed from interstellar clouds of gas and dust that contain hydrogen
• Protostar


  Interstellar cloud collapse

  Increasing in temperature as a result of its internal gravitational attraction
• Stable star

  Inward force of gravitational attraction = outward force

  Because of high temperature in the centre of the star
• All stars eventually run out of hydrogen as fuel for the nuclear reaction
• Star life cycle

  1. Star expands: giant

  2. Big star expands: red supergiant

  3. Red giant: planetary nebula with white dwarf star

  4. Red supergiant explodes: supernova, forming nebula with new heavier elements and leaving behind neutron star or black hole

  5. Nebula from supernova: form new stars with orbiting planets
• Milky Way


  • One of many billions of galaxies making up the Universe
  • Diameter of approximately 100 000 light-years
• Redshift

  Increase in the observed wavelength of electromagnetic radiation emitted from receding stars and galaxies
• Light emitted from distant galaxies appears redshifted in comparison with light emitted on the Earth
• Redshift in the light from distant galaxies is evidence that the Universe is expanding and supports the Big Bang Theory
• Cosmic microwave background radiation (CMBR)


  Microwave radiation of a specific frequency

  Observed at all points in space around us
• CMBR production

  1. Produced shortly after the Universe was formed

  2. Expanded into the microwave region of the electromagnetic spectrum as the Universe expanded
• Galaxy speed v

  Speed at which a galaxy is moving away from the Earth, found from the change in wavelength of the galaxy's starlight due to redshift
• Galaxy distance d

  Distance of a far galaxy, determined using the brightness of a supernova in that galaxy
• Hubble constant H0

  • Ratio of the speed at which the galaxy is moving away from the Earth to its distance from the Earth
• d/v = 1/H0


  An estimate for the age of the Universe

  Evidence that all the matter in the Universe was present at a single point