Transcript The Sun

Our Star
The Sun
Sun Statistics
Radius: 700,000 km
109 Earth Radii
Mass: 2 x 10^30 Kg 333,000 Earth Masses
Density: 1.4 g/cm³ (Mostly Gas, increases
greatly with depth to 150 g/cm³)
Surface Temperature: 5780º K (9900º F)
Core Temperature: 15,000,000°K
Composition: 71% Hydrogen, 27% Helium,
2% Other heavier elements.
Power Output: 4 x 10^26 watts
The Sun, an Energy Source
The Sun is the source of nearly all energy on Earth.
(Exceptions?)
The source of this energy lies in the Core.
There Fusion reactions turn hydrogen into helium releasing
energy.
The energy then starts it journey out, and to Earth, etc.
First it passes through the Radiative Zone, where photons are
emitted, absorbed and re-emitted by atoms.
Then it passes through the Convection Zone, there it is carried
by rising currents to the Photosphere.
It is the thin Photosphere that radiates the light that we see and
feel on Earth.
Inner Layers of the Sun
Core: out to .3R
15-8 million °K
Radiative Zone:
.3R --.7R
8-2 million °K
Convection Zone
.7 -- .99 R
2 million °K to
6000 °K
Photosphere
5780 °K
Granulation
Granulation is when Rising Convection Currents make
photosphere look like glowing grains called granules.
The center of the granules are where the currents
rise.
They glow brightly with the heat carried up
The edges are where the currents go back down.
There it is cooler and thus darker.
Layers of the Sun’s Atmosphere
The Chromosphere is
the dim lowest layer of
the Sun’s atmosphere.
It & the Corona are
only visible during an
eclipse.
It is colored red because
it is cooler at 4500ºK
It consists of spiky
Spicules, jets of gas The Corona is the outer layer of the
thousands of kilometers Sun’s atmosphere. It glows bluewhite because its temperature
long.
Temperatures begin to reaches 50,000°K.
rise at 2000 km out. It extends out 100’s thousands of km.
Hydrostatic Equilibrium
The gravity of the mass of the Sun creates great
pressure and thus density.
This pressure, and the heat it creates make the
fusion in the core possible.
But
The fusion creates forces that push back out
against the pressure.
These forces balance making the “Hydrostatic
Equilibrium” that keeps the Sun the size it is.
How do we know all this?
The color of the light tells us the temperature of
the Photosphere, Chromosphere, and Corona
When fusion occurs particles called neutrinos are
released that travel out from the core.
By counting them we can calculate the rate of
Fusion.
Finally Solar Seismology studies “Sunquakes” to
understand the Sun’s interior.