Topic 10 - Solar Astronomy

• what is the solar wind?

  a constant flow of charged particles flowing outward from the sun
• should u look at the sun directly with ur eyes?

  never
• how to observe the sun safely?

  telescope projection method
• how does the telescope projection method work?

  his involves pointing the telescope at the Sun and using the eyepiece (NOT LOOKING INTO IT) to project the image of the Sun onto card or a smooth surface
• what do hydrogen alpha filters do?

  they only let through light at this wavelength, reducing the light intensity
• what are the 4 internal divisions of the sun?

  core

  radiation zone

  convective zone

  photosphere
• what is the temperature at the core?

  over 15,000,000°K
• what two external layers make up the suns atmosphere?

  chromosphere and corona
• which layer of te sun can be observed during a solar eclipse?

  corona
• which external layer stretches out for millions of kilometres from the chromosphere?

  corona
• what temperature does the corona reach?

  2,000,000°K
• what takes place in the core of the sun due to high internal pressure?

  nuclear fusion
• what is fused together and produced in the core?

  hydrogen nuclei fuse to form helium nuclei
• The corona also emits X-rays
•  Some particles are pulled back towards the Sun while others are so energised that they flow outwards from the corona at high speeds to form the Solar Wind.
• what is the photosphere?

  the surface layer of the sun
• what moves through the radiation and convective zones?

  light and heat
• why do high energy gamma rays take soo long to pass through the radiative zone?

  the density is so high they only travel a short distnace before hitting a proton and being absorbed them re-emitted in a random direction.
• what occurs in the convective zone?

  suns energy moves outwards towards its surface
• what occurs in the radiation zone?

  energy transfer by gamma ray photons generated by nuclear fusion
• what can be used to view the chromosphere?

  h-alpah filter
• what is the nuclear fusion process in the sun called?

  proton proton chain
• how does proton proton fusion occur?

  kinetic energy is high enough to overcome electrostatic repulsion
• the difference in mass between the reactants and the products is converted into energy (E=mc^2)
• what are sunspots?


  Dark spots on the surface of the Sun.
• why do sunspots appear dark?

  they are cooler than the surrounding area
• how do sunspots form?

  local concentrations of the suns magnetic field inhibit convection
• what are the two regions of a sunspot?

  Umbra, Penumbra
• what are features of the umbra?

  darker region

  4000K
• features of penumbra?


  lighter region

  5600K
• how can sunspots be viewed?

  telescope projection method
• what can sunspots be used to measure?

  rotation period by measuring the longitude difference in a set time
• how long is a sunspot cycle?

  11 years
• what does the sun consist of?

  a shpere of hot plasma (ionised gas)
• where does the sun rotate faster?

  equator
• what is the rotational period at the equator of the sun?

  25 days
• what is the rotational period of the sun at the poles?

  36 days
• what are coronal mass ejections (CMEs)?


  large scale ejections of plasma from the suns corona
• hoe does the earth protect itself form the solar wind?

  Magnetosphere
• what are the two zones around the earth where energetic charged particles from the sun are trapped?

  Van Allen Belts