Astronomy - Chapter 4 - Galaxies and Cosmology - COSMOLOGY
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- Created on: 11-04-13 16:46
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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
- In 1989 NASA launched the COsmic Background Explorer (COBE) satellite equipped with very sensitive detectors to study CBM
- 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
- Big Bang Theory
- 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
- Doppler Principle
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