1. The Sun
Chapter 28

2. 28.1 – Structure of the Sun
Throughout most of history people thought the sun’s energy came from fire
Not until the last 100 years did scientist discover the source
There are three layers to the sun: the core, the inner zones, and the atmosphere

3. 28.1 – The Core
The core is at the center of the sun and makes up about 10 percent of the sun
The temperature at the core is about 15,000,000 oC
No liquid or solid can exist at that temperature

4. 28.1 – The Core
75 % of the sun is made of Hydrogen and the rest is mostly helium
Hydrogen fusion is the process by which the sun gets its energy
Two hydrogen atoms collide and combine to form a helium atom
When this happens energy is given off

5. 28.1 – The Inner Zones
The energy produced in the core moves through two inner zones before reaching the surface
The first zone around the core is the radiative zone.
The temperature here is about 2,500,000 oC

6. 28.1 – The Inner Zones The second zone is the convection zone.
It has a temperature about 1,000,000oC
Hot gases carry energy to the surface and cooler gases fall to gather more energy
Heat gets to the surface by gases rising and falling

7. 28.1 – The Sun’s Atmosphere
Surrounding the convection zone is the atmosphere.
Although the sun is all gas the atmosphere is the upper most region of the sun
The atmosphere has 3 layers

8. 28.1 – The Sun’s Atmosphere The first layer is the photosphere
The temperature here is about 6,000 oC
Most energy given off here is from visible light

9. 28.1 – The Sun’s Atmosphere
The second layer of the atmosphere is the chromosphere, or color sphere
Its temperature is between 4,000 and 50,000 oC

10. 28.1 – The Sun’s Atmosphere
The outer most layer is the corona or crown
This layer is a huge cloud of gas heated to a temperature about 2,000,000 oC
Some electrically charged particles escape from the corona, they are called the solar wind

11. 28.1 – The Sun’s Atmosphere
The chromosphere and corona are not usually seen from earth during the day
If we have a solar eclipse we can see them around the outline of the moon