Astronomy - Chapter 1 - Earth, Moon and Sun - SUN
- 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
- About the Sun
- At the Sun’s CORE, the gas pressure is high and collisions of particles of gas are frequent
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