1. The Sun
The SUN
Chapter 29
Chapter 29

2. H-R Diagram
sun

3. Composition of the Sun
A spectrograph splits light into its different visible wavelengths. Each element produces a unique pattern of spectral lines.
Used to determine what gaseous elements are present in the sun.
Mostly Hydrogen and Helium.

5. Nuclear Fusion Hydrogen + Hydrogen fuse to form a Helium.
Neutrinos are released.
Some mass is lost and is released as energy (heat).
* This is where the sun’s energy comes from.

6. Einstein’s Theory of Relativity
“a small amount of matter
yields a large amount of
energy”
E = mc2
E = Energy produced
m = Mass changed
c = speed of light
Einstein’s equation allowed scientists to explain the huge amounts of energy produced by the sun.

7. The Sun’s Interior Core Radiative Zone Convective Zone Gas
15,000,000 oC
25% total mass
Extreme pressure
Fusion reactions occur here
Radiative Zone
2,000,000 to 7,000,000 oC
Energy moves by electromagnetic waves or radiation.
Convective Zone
2,000,000 oC
Energy moves by convection cells heated by the radiative zone.

8. The Sun’s Atmosphere Photosphere Chromosphere Corona Innermost layer
“Sun’s Surface”
“Sphere of Light”
Gases that have come
from the convective zone
6,000 oC
Visible surface
(visible light emitted)
Sunspots are found here
Chromosphere
“Color Sphere”
Glows red
4,000 to 50,000 oC
Gas jets shoot out
Visible during solar eclipse
Corona
Outermost layer
Can get to 1,000,000 oC
Visible during eclipse

9. Solar Activity Internal and external gases are in constant motion.
Due to
Energy produced in the sun ( fusion )
Force of gravity (sinking and cooling) = convection
Rotation of the sun on its axis
Gases at equator move faster – 25.3 earth days
Gases at poles move slower – 33 earth days

10. Solar Wind A stream of charged particles (mostly electrons
and protons) released from
the upper atmosphere of
the Sun
The source of the solar wind is the Sun's hot corona.
The temperature of the corona is so high that the Sun's gravity cannot hold it.
The solar wind streams off of the Sun in all directions at speeds of about 400 km/s (about 1 million miles per hour).
It interacts with Earth’s magnetosphere in the upper atmosphere (thermosphere – ionosphere):
geomagnetic storms can knock out power grids on Earth
the auroras (northern and southern lights)
the plasma tails of comets that always point away from the Sun

11. Sunspots – cool, dark areas of the gas of the photosphere.
Magnetic field causes some gases to move (during convection) more slowly than other gases.
Less energy is being transferred.
Cooler areas
appear darker.
Link

12. Sunspot Cycle
Sunspot cycles Last 11 years: increases – peaks – decreases
Caused by changes in the sun’s magnetic field
Shows that the sun rotates
Peaks coincide with increased solar ejections:
prominences, solar flares, and coronal mass ejections.

13. Prominences Solar Flares
Great clouds of glowing gases
Form huge arches
Associated with the chromosphere
Most violent solar disturbances
A sudden outward eruption of electrically charged particles (electrons and protons)
May reach 20,000,000 oC
Link
Link

14. Coronal Mass Ejections
Parts of the corona thrown into space
As these particles become part of the solar wind, they eventually strike Earth’s magnetosphere.
Create geomagnetic storms that affect Earth
Link