Astronomy - Chapter 4 - Galaxies and Cosmology - COSMOLOGY

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  • Astronomy - Chapter 4 - Galaxies and Cosmology - COSMOLOGY
    • Doppler Principle
      • The Doppler Principle can show radial velocity
      • RED SHIFT shows that the star/galaxy is moving away
      • BLUE SHIFT shows us that the star/galaxyis moving towards us
      • An ORANGE band shows us that there is a constant distance/not moving
      • A good example is the Andromeda Galaxy - loads of BLUE SHIFT
    • Radio velocity equation
      • In the extra page
    • Edwin Hubble
      • Hubble discovered that the Universe was expanding
    • CMB Radiation
      • COSMIC MICROWAVE BACKGROUND RADIATION is one of the main arguments that is in favour of the BIG BANG theory
      • Optical telescopes show that space between galaxies at microwave wavelengths there is a faint 'glow' of radiation
      • CMB radiation affects the universe and perfectly matches the radiation emitted by a BLACK BODY with a temperature of 2.7k
    • Dark Matter
      • The term DARK MATTER means matter that is invisible to astronomers
      • Dark Matter does not emit or reflect radiation but has detectable  gravitational
      • It's nature is unknown but could include: black holes, neutrinos and exotic particles known as WIMPs
        • WIMPs = Weakly Interacting Massive Particles
      • Dark matter was first proposed in 1933 by Swiss astrophysicist Fritz Zwicky
      • Most cosmologies agree that dark matter contributes over 90%of the total mass of the Universe
    • Big Bang Theory
      • Working backwards in time, most cosmologists  think that the universe has always been expanding and that it began as an extremely small initial point in an 'event' - the BIG BANG
    • COBE and WMAP
      • In 1989 NASA launched the COsmic Background Explorer (COBE) satellite equipped with very sensitive detectors to study CBM
        • The data confirmed the uniform nature (isotropy) of the CMB on a large scale
        • But it also detected minute fluctuationsor 'ripples' in the radiation
        • This allowed cosmologiststo study how matter (that would eventually develop into galaxies) and energy were distributed in the early universe
      • Wilkinson Microwave Anisotropy Probe (WWAP) was launched in 2001 by NASA
      • (WWAP) in order to study the CMB in more detail and help cosmologiststo refine their models of composition,  evolution and age of the universe
      • It also provided data that enabled cosmologiststo estimate the contributionof DARK MATTER in the universe and confirm the existence of DARK ENERGY
    • The Universe
      • Big Bang Theory
        • Working backwards in time, most cosmologists  think that the universe has always been expanding and that it began as an extremely small initial point in an 'event' - the BIG BANG
      • Cosmologists  now agree that since all the distant galaxies are moving away from us - the universe is expanding
      • More recent observation of some of the most distant known galaxies (quasars) with extremely    high red shifts
    • Dark Energy
      • 10 years ago there was a general consensus among cosmologiststhat the expansion of the Universe was slowing down
      • Two teams of astronomers used observationsof distant supernovae to suggest that the expansion was actually accelerating  under the influence of a mysterious repulsive force of negative gravity
      • There has been further evidence from a wide diversity of experiments to suggest that the expansionof the universe is in fact 'real'
      • It was cosmologist Micheal Turner who coined the term DARK MATTER as this source

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