Download THE SUN: OUR STAR

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.
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.
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.
•
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 star’s 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.
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 away 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.
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.
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.
2. Nicknamed the sun’s power plant.
3. Where all of the sun’s fusion takes place.
B. Photosphere:
1. First layer of the sun’s atmosphere.
2. Often called the “sun’s surface”.
3. Layer of the sun in which light is given off.
C. Chromosphere:
1. The outer, less dense, layer of the sun’s
atmosphere.
2. Red in color due to cooler temperatures.
3. Solar Flares take place there.
a.) Solar Flare- gases, near hot spots, that shoots
outward, at high speeds.
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 sun’s corona.
5. Both the solar wind and solar flares are
responsible for Aurora Borealis.
a.) Aurora Borealis- When earth’s 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.
A. What are sunspots?
V. 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 earth’s
weather.
6. No data has ever confirmed that this pattern effects anything
on earth.
• SOLAR PROMINENCE-
huge arching columns
of gas projected from
the chromosphere into
the corona
-various shapes
and forms
-associated with
the magnetic fields of
sunspots
•
Point A is where the Sun starts Hydrogen fusion
Point B is where about half of the supply of the
hydrogen in the core has been used up. This is
where the Sun is in its lifetime right now.
Point C is reached when there is no more hydrogen
in the core and the fusion of hydrogen starts in the
shell around the core. The radius of the Sun will
swell to 40% larger than its present size and twice
its present luminosity.
At point D, approximately one and a half billion
years later, the surface of the Sun will be 3.3 times
the size it is now and have a temperature of about
4300 degrees. The temperature on Earth will
increase by 100 degrees, causing all the seas to
evaporate and destroying life on Earth as we know
it. Within another 250 million years, the Sun will
grow 100 times larger than it is now and 500 times
more luminous.
At point E the core temperature of the Sun will rise
so high that in one bang, all the rest of the helium
will fuse into carbon, causing one third of the solar
envelope to be thrown out into space.