Energy from our Sun

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Energy from our Sun
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Properties of the Sun

• Largest object in our solar system
• Contains 99 of all the mass of the solar system
• Suns mass controls motion of planets and other
  objects

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Properties continued

• Density in the center is thirteen times the
  density of lead
• Temperature of the interior is 1x107 K
• State of matter is plasma
• Astronomers rely on computer models for an
• explanation of the Suns interior

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Solar Composition

• The Sun is primarily composed of hydrogen (73.4)
  and helium (25) and small amounts of other
  elements.

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Suns atmosphere

• Photosphere layer around the Sun that is visible
• - 400 km thick - temperature 5800 K
• Chromosphere layer above the photosphere
• - 2500 km thick
• - temperature at the top is 30,000 K
• Corona top layer of the Suns atmosphere
• - several million km thick
• - temperature range of 1-2 million K

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• Solar wind wind of charged particles that flow
  out from the corona

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Solar interior

• Fusion (combining of nuclei) takes place within
  the core of the Sun under high pressure and
  temperature
• Hydrogen nuclei fuse to form helium
• The mass lost in the fusion of hydrogen to helium
  is converted to energy, which powers the sun

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Energy from the Sun

• Above Earths atmosphere, 1354 J of energy is
  received in 1 m2 per second (1354 W/m2)
• Thirteen 100-W
• light bulbs could
• be operated by the
• solar energy that
• strikes 1m2

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• Energy of the Sun is produced in the core
• The radiative zone is above the core and extends
  into the photosphere
• Energy is transferred from particle to particle
  by radiation
• The convective zone is above the radiation zone

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Transfer of energy to Earth

• Radiation is the transfer of energy through space
  by visible light, UV radiation, and other forms
  of electromagnetic waves
• 35 of the solar radiation is reflected into
  space by Earths surface, atmosphere, or clouds
• 15 is absorbed by the atmosphere
• 50 is absorbed (in)directly by Earths surface

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