Chapter 28, sections 1 & 2 The Sun
Elements within the
Scientists use spectroscopic analysis of the sun’s rays to show the
sun →
elements that are in the sun. Scientists have determined that
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Layers of the sun →


75% of the sun’s mass is hydrogen gas and
25% of the sun’s mass is helium gas
The sun is layered. Although each layer has specific characteristics, if
traveling through the sun you could not tell one layer from the next
1) The core:
 Innermost, and hottest layer of the sun (15,000,000 C)
 Gravity is so strong due to the size of the sun that the core is

10x as dense as iron
Due to extreme pressure and heat, electrons strip away from the
nucleus of atoms, allowing nuclear reactions to occur
Nuclear fusion- nuclei of atoms combine to form larger atoms
Hydrogen fusion- nuclei of hydrogen combine to form helium atoms
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Hydrogen fusion is a type of nuclear fusion. In any kind of nuclear fusion
a huge amount of energy is released
2) The inner zones:
 Energy produced in the core moves through the inner zones
 There are two parts of the inner zone;
o the radiative zone- energy moves in the form of radiation
(electromagnetic waves), and the
o convection zone- energy moves in the form of convection
(transfer
(energy
through liquids or gases). In the convection zone cool
gases become less dense and sink back towards the core
3) The atmosphere:
 The outermost layer of the sun, surrounding the convection zone is
the atmosphere
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The atmosphere is divided into three layers;
o Photosphere- the visible portion of the sun. This layer has
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Solar activity →
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areas where gases rise from and sink back into the
convection zone called granulation
o Chromosphere- a reddish layer of the sun only visible in a
solar eclipse
o Corona- the outermost layer of the sun that blends into
space, and prevents the sun’s atomic particles from escaping
Some electrically charged atomic particles from the corona do escape
into space, creating solar winds
The gas layers of the sun are constantly moving. The sun also rotates on
an axis
The combination of the moving gases and its rotation creates a magnetic
field
The magnetic field slows down the gases moving within the convection
zone so they are cooler.
Sunspots- cooler areas that appear darker than the surrounding
photosphere
Sunspots disappear and new ones form at the sun’s equator
Sunspot cycle- the number of sunspots vary in an 11 year cycle
When the number of sunspots is low, the sun is less active, and it is cooler
on earth. When the sunspot number is high, it is hotter on earth
Sunspots create prominences- huge arches on the sun’s surface that lasts
for weeks or months
Solar flares are even larger than prominences which increase solar winds
causing changes in earth’s magnetic field
Auroras are bands of light in the sky which are created from solar winds
strike molecules in earth’s upper atmosphere
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