The Sun

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The Sun

• I Life Cycle of the Sun

A. Stars are born in nebulas.
B. Nebula- A rapidly condensing cloud of gas and
dust.
C. Star Pre-life Steps
1. Gases rapidly condense to star dust.
2. Masses form
3. Masses collide with others to form larger
pieces of star stuff.
4. Gravitational forces increase.
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5. This sets off a snow ball effect or chain
reaction.
6. One very large object collects most of the
star stuff.
7. Density increases.
8. Temperature increases.
9. Fusion begins to take place.
a.) Fusion- The process in which two atoms
fuse together to form another substance.

b.) In the suns case there were two atoms of
Hydrogen, which fused together to form Helium.

10. When fusion out put becomes balanced with
the gravity of the large object, a star is
born.
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• II. Life Cycle Steps

A. Main Sequence- The beginning phase of life
for all stars.
1. Every Star has a main sequence.
2. The star spends most of its life in this
phase.
3. Fusion continues for billions of years.
4. When a stars hydrogen begins to run out, the
star begins to enter its next phase.
B. Red Giant Phase- Beginning stage of death for
small medium size stars.
1. The fusion and gravity of a star becomes
unbalanced do to hydrogen running out.
2. This makes the star collapse in on it self.
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3. Another round of fusion is triggered. This
time helium fusses together.
4. The star swells to several times its original
size
5. Remaining gas floats way as the star cools.

C. White Dwarf- The remaining core of a small
or medium star after the red giant phase is over.

1. The stars weight during the red giant phase
will make the star collapse in on it-self.
2. All that is left of the star now is a
collapsed core.
3. About the size of earth.
D. Black Dwarf- The final stage of death of a
small or medium size star.
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1. After the stars core cools enough that its
luminosity is zero a star enters this phase of
life.
2. All that is left is a tiny ball of lifeless
material

• III. Properties of the Sun

A. Size
1. More than 99 of all matter in our solar
system is in the sun.
2. About 110 times the diameter of the earth

3. The sun could hold more than a million
earths.
4. The mass of the sun is 745 x greater than all
of the planets put together.
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B. Distance
1. Earth is 1 AU away from the sun. (93 million
miles)
2. Light takes about 8 min. and 20 sec. to reach
earth.
C. Temperature
1. Interior temperatures can be as high as 15
million degrees C.
2. Atmosphere temperatures can be as high as
6,000 degrees C.

• IV. Layers of the Sun

A. Core
1. The area where the sun makes its energy.
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2. Nicknamed the suns power plant.
3. Where all of the suns fusion takes place.
B. Photosphere
1. First layer of the suns atmosphere.
2. Often called the suns surface.
3. Layer of the sun in which light is given off.

C. Chromosphere
1. The outer, less dense, layer of the suns
atmosphere.
2. Red in color due to cooler temperatures.
3. Solar Flares take place there.
a.) Solar Flare- gases, near sun spots, that
shoots outward, at high speeds.
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D. Corona
1. Outer most layer of the sun.
2. Can only be seen during a solar eclipse.
3. Will damage your eyes if you look at the
solar eclipse without protective eye ware.
4. Solar wind takes place here.
a.) Solar wind- electrical charged
particles that escape from the suns
corona.
5. Both the solar wind and solar flares are
responsible for Aurora Borealis.
a.) Aurora Borealis- When earths
atmosphere interacts with the particles
from solar flares and solar wind,
beautiful colors of light glow in the
sky.
b.) Sometimes called the Northern Lights.

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• V. Sunspots

A. What are sunspots?
1. Sunspots- areas of the photosphere that
appear to be dark because they are cooler than
the areas around them.
2. We learned that the sun rotates by studying
sunspots.
3. They can appear and disappear at times.
4. A sunspot maximum will take place every 10 to
15 years.
5. Some data suggest that this may have an
effect on earths weather.
6. No data has ever confirmed that this pattern
effects anything on earth.