Transcript Our Sun - LWC Earth Science

Ch 24.3: The Sun
 Be able to describe the
size and composition of
the sun.
 Explain how the sun
produces energy.
 Identify and define the
layers of the sun.
Our Sun
 How big is our star, the
sun?
 The sun is a medium
size star.
– 1 million earths could fit
inside the sun.
 What is the sun made out
of?
 The sun is about:
– 75% hydrogen
– 25% helium
Our Sun
 How old is the sun?
– It is 4.5 billion years old (middle-aged).
– Could last 10 billion years.
 What is the chemical composition of the sun?
– The sun does not have a solid surface, made of only
plasma (beyond gas - PLASMA)
Our Sun
 How much of the solar system makes up the
sun?
– The sun contains 99.8% of the solar systems mass.
 How does it create energy?
– Energy from the sun is made by nuclear fusion.
Does our Sun spin like the Earth?
 This is because our Sun actually spins. (Just like our
planet Earth, only much more slowly.) It takes about
27 days for the Sun to make one complete
rotation.
The Layers of the Sun:
Because the sun is made of gas, no
sharp boundaries exist between its
various layers. Keeping this in mind,
we can divide the sun into four parts:
the solar interior; the visible surface,
or photosphere; and two atmospheric
layers, the chromosphere and
corona.
Solar Interior
Core
 15 Million °C
 Nuclear fusion
– Hydrogen to Helium
Parts of the Sun
Core
Solar Interior

 Radiation zone (14 – 1.5 Million °C)
 Convective zone (1.5 Million °C)
Parts of the Sun
Convective Zone
Radiation Zone
Core
The Visible Surface
 Photosphere
(5,500 °C)
– Sphere of light
– Surface of the Sun
– What we see here on
Earth.
– It exhibits a grainy texture
called granules, produced
by convection.
Parts of the Sun
Convective Zone
Radiation Zone
Core
Photosphere
The Atmosphere
 Chromosphere
(8,000 °C)
– Color sphere
– Red in color
– It is a relatively thin, hot
layer of incandescent gases
a few thousand kilometers
thick.
The Atmosphere
 Corona (1 Million °C)
– Outermost layer
– Extends for millions
of kilometers
– Solar wind is a stream
of protons and electrons
ejected at high speed
from the solar corona.
Parts of the Sun
Convective Zone
Radiation Zone
Chromosphere
& Corona
Core
Photosphere
 You can see the
chromosphere and
the corona during a
total solar eclipse
Ch 24.3: The Sun
 Be able to describe the
physical features on
the surface of the sun.
Sunspots
 Sunspots are dark
spots on the
photosphere
 They have cooler
temperatures
(3,000°C) than the
photosphere.
Sun Spots
 Sun Spots are cooler
because of magnetic
fields slow down
convection, less heat
is transferred from the
core of the sun to the
photosphere
Sunspot Cycle
Sunspots vary on a
11-year cycle
At the peak of the
cycle there may be
more than 100
sunspots.
Also at the peak of
the cycle the Sun is at
its brightest.
Sun Spot Cycle
Parts of the Sun
Convective Zone
Radiation Zone
Chromosphere
& Corona
Core
Sunspot
Photosphere
Solar Flares
 Sudden outward
eruptions of
electrically charged
atomic particles
 During the peak in the
sunspot cycle, 5 to 10
solar flares may be
visible each day

Parts of the Sun
Convective Zone
Radiation Zone
Chromosphere
& Corona
Core
Sunspot
Photosphere
Solar Flare
Prominence
Prominences are huge cloudlike arches that extend
from one sunspot to
another.
Prominences are ionized
gases trapped by
magnetic fields.
Parts of the Sun
Convective Zone
Radiation Zone
Chromosphere
& Corona
Prominence
Core
Sunspot
Photosphere
Solar Flare
Solar Wind
Is a constant stream of protons and
electrons ejected at high speed from
the sun
Auroras
The result of solar flares & solar wind,
are bright displays of ever-changing
light caused by solar radiation
interacting with the atmosphere in the
region of the poles.