Astronomy - Chapter 1 - Earth, Moon and Sun - SUN

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  • Created by: Georgina
  • Created on: 09-04-13 14:16
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  • Astronomy - Chapter 1 - Earth, Moon and Sun - SUN
    • About the Sun
      • Sun's diameter = 1.4 billion km
      • Distance from Earth = 150 million km/1 astronomical  unit
      • The Sun is VERY important: it provides heat, light and energy for the requirements  of life
      • How to safely observe the Sun: using a special high-quality H-alpha or Mylar filter
      • Another safe method is by using a pin hole camera and focus on the image of the Sun reducing the brightness to a safe level
      • The Sun's rotation period is from 25 days at the EQUATOR and 36 days at the poles
    • Atmosphere
      • The Sun's atmosphere has a rotating sphere of gases of hydrogen (75%) and helium (25%)
      • The Sun has a visible 'surface' called PHOTOSPHERE - it's temperature is 5800 k
      • Solar Atmosphere
        • There is also a thing called the Corona. The Corona has a temperature of 2000 k - hot enough to emit X-rays
    • Sunspots
      • Sunspots are small dark patches on the photosphere - they are the size of Earth or even bigger
      • Sunspots are cooler areas of the photosphere and they occur in pairs
      • The structure of a sunspot is:
        • A PENUMBRA - the lighter area (surrounding the darkest bit) - temperature - 200 k cooler than the photosphere = 5,600 k
      • Sunspots move across the Sun. This is because the Sun moves on it's axis and
      • Astronomers take photos everyday at the same time each day
      • The Butterfly Diagram: plotting the sunspot latitude against time on a chart - it's general pattern gives a butterfly affect
      • Sunspots are made on the Sun's surface and are over an 11 year cycle and are caused by a very high magnetic  field
        • At the beginning of an 11 year cycle the sunspots appear at very high
    • Sun's Energy
      • The Sun's source of energy is Nuclear Fusion
      • These fuse by thermonuclear fusion to produce helium nuclei and vast amounts of energy.Heat energy from the CORE maintains the chain reactions of nuclear fusion
      • Temperature rises to 15 million K, which is hot enough for hydrogen atoms to be stripped of their electrons, leaving just the hydrogen nuclei (bare protons)
      • At the Sun’s CORE, the gas pressure is high and collisions of particles of gas are frequent
    • Solar Winds
      • A solar wind is plasma flowing away from the Sun
      • At millions of degrees the electrons are stripped of the hydrogen and helium atoms. This leaves charged nuclei and protons in a plasma
      • There is huge energy involved so their kentic energy becomes overcomes by the gravitational pull
      • Then they fly out from the Sun towards Earth reaching a speed of 400  km/s
      • Aurorae
        • Auroraes are formed when solar winds send out charged particles which then interact with the magnetic field and shoot towards the poles
        • They then excite/ionise nitrogen or oxygen particles which then emit photons of light
        • When oxygen and nitrogen get excited they emit red, blue and green light
        • The photons emitted is called the aurorae
    • Sun's different wavelength
      • Observing the Sun a t different wavelengths gives a clear image of the Sun
      • We use X-ray wavelength you can study the life cycle of solar magnetic field events in amazing detail and an better understanding of the corona
      • We use visible to telescopes to do detail in Sunspots, solar winds and the Corona
      • Using H-alpha wavelength - it blocks out all other wavelength and is used to show detail on the surface of the Sun and Sunspot activity
  • At the Sun’s CORE, the gas pressure is high and collisions of particles of gas are frequent



Very Helpful! :D

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