Transcript Unit 8 Chapter 29

Unit 8 Chapter 29
The Sun
We used to think that our sun was a ball of fire in the sky. Looking
at our sun unaided will cause blindness.
The Sun’s Energy
Because the sun is so brilliant, scientists need special instruments and filters to
view the sun and it’s properties.
Composition of the Sun
Scientists can use a spectrograph to look at the wavelengths that are emitted
by the sun. They have discovered that about 75% of the sun’s mass is
hydrogen and a combination of hydrogen and helium make up about 99% of the
mass.
Solar telescopes-allow scientists to look at the sun safely (Helios is a satellite
orbiting and observing the sun).
Nuclear Fusion
Fusion is the combining of the nuclei of lighter elements to form heavier ones.
It is the source of all stars light energy.
The Final Product
The energy released during the three steps of nuclear fusion causes the sun to
shine and gives the sun its high temperature.
Mass Changing into Energy
E=mc2 Energy = mass x the speed of light squared
Because the star is a place of intense heat and pressure, the atoms are torn
apart into their component nuclei and electrons.
By using Einstein's equation, astronomers were able to explain the huge
quantities of energy produced by the sun. The sun changes about 4 million tons
of mass into energy every second. Yet this amount of mass is small compared
with the total mass of the sun.
Some Scientists feel that plasma is created here. Plasma is the state that
helium and hydrogen exist inside a star. It is the fourth state of matter consisting
of charged particles. Because of the speed that they move, they hit each other
and fuse together.
The Sun’s Interior
The Core
The Temperature is about 15,600,000oC
It makes up about 25% of the diameter
The Radiative Zone
The temperatures from about 2,000,000oC to 7,000,000oC
The Convective Zone
The temperature is about 200,000oC
In this layer, the cooler gases sink and the warmer ones rise
The Sun’s Atmosphere
Surrounding the convective zone is the sun's atmosphere. Although the sun is
made of gases, the term atmosphere refers to the uppermost region of solar
gases. This region has three layers—the photosphere, the chromosphere, and
the corona.
The Photosphere
This is the visible layer of the sun because most energy given off is in the form
of visible light.
The temperature is about 6000oC
It contains dark spots that are areas with a cooler temp. 3800oC
The Chromosphere
Temperatures range from 6,000oC to 50,000oC
It has plumes that jet out about 16,000 km from the surface
It causes hydrogen to emit reddish light
The Sun’s Outer Parts
It is the outer atmosphere. It is very hot, about 1,000,000oC to 3,000,000oC.
Section 2 Solar Activity
Sun Facts:
• The sun’s diameter is approximately
1,380,000km (~100 earth’s). It is 94,000,000
miles from the earth. It takes 8 minutes 20
seconds for sunlight to reach the earth. It would
take 195 years at 55 mph to drive to the sun.
The sun’s rotation period at the equator is
approximately 25.3 earth days and 33 earth
days at poles. This gives it an average rotation
period of 27 earth days.
Sun Spots
The Chinese were the first to discover sun spots. Galileo
discovered that the spots move in a regular pattern (he went blind
looking at the sun)
Sun Spots are dark spots on the sun (slightly cooler than
photosphere). They occur in pairs, one in north, one in south and
can last for a short time like hours, days or a longer time like
weeks and months. They have magnetic properties
Sun Spot Cycle
The cyclic period is approximately 11 years. The period starts
when the spots are at peak they have about 100 and continue
until they are at a low.
Solar Eruptions
They are bursts of energy that leave the sun. They can be caused by
solar flares (a flame leaving the sun. They can disrupt electric signals
and radio transmissions due to magnetic storms they can produce.
Prominences
They are great clouds of glowing gases. Some may last several
weeks, some only for a few hours.
Solar Flares
They are the most violent disturbances. They are sudden
outward eruptions of electrically charged particles that can
disrupt electrical signals.
Coronal Mass Ejection
They are gases thrown into space.
Auroras
Auroras are usually seen close to Earth's magnetic poles because electrically
charged particles are guided toward Earth's magnetic poles by Earth's
magnetosphere. The electrically charged particles strike the atoms and gas
molecules in the upper atmosphere and produce colorful sheets of light.
Depending on which pole they are near, auroras are called northern lights—or
aurora borealis or southern lights—or aurora australis.
It has been seen as far south as 35 degrees North