Educational presentation on basic solar structure and activity.

1. The Sun:
Our Star
By: Megan Angeli

2. What is the Sun?
• The Sun is a massive star that provides
heat and light for our solar system.
• It is essential for all life on Earth.
• Its gravity keeps all of the planets lined up
in their orbits.

3. How big is the Sun?
• The Sun is 1000 times more massive than
all the planets put together!
• If we built a scale model of our solar
system with the Sun as a grapefruit, the
Earth would be the size of a pinhead
orbiting about 15 meters away!

4. What is the Sun made up of?
• The Sun is made up of burning, churning
hot gas, also known as plasma.
• The different properties of plasma, such as
temperature and density, create various
layers within the Sun’s structure.

5. Solar Structure
The Core, Radiation Zone, and Convection Zone make up the Sun’s
INTERIOR.
The Photosphere, Chromosphere, and Corona make up the Sun’s
ATMOSPHERE.
LET’S EXPLORE THESE LAYERS, STARTING FROM THE INSIDE!

6. The Core
• The core is the source of the Sun’s energy.
• Energy is created through a process called
Nuclear Fusion:
– Atoms can travel so fast that when they collide, they “fuse”
together and release energy
– Hydrogen atoms within the Sun fuse to form Helium and release
energy we receive as heat and light
• Temperature: 15,000,000 K

7. The Radiation Zone
• Here, energy moves up and out from the
core traveling as photons
– Photons are physical “packets” of energy
• The temperature here is cooler than the
core: about 10,000,000 K.

8. The Convection Zone
• Convection is a process in which warmer,
less dense matter rises, and cooler, more
dense matter sinks.
• As a result of convection, the energy in this
layer moves up with warmer plasma and
sinks with cooler plasma.
• Cools down to 5,000,000 K in this layer

9. The Photosphere
• The photosphere is the visible surface of the Sun.
• This surface turns and churns like a pot of rapidly boiling
water.
• This layer has sunspots
– Parts of the Sun’s surface get interrupted by intense magnetic
fields and appear as blackened spots in camera images of the
Sun
• Temperature in this first layer of the Sun’s atmosphere
dramatically decreases to about 6000 K

10. The Chromosphere
• The chromosphere is the “middle layer” of the Sun’s
atmosphere
• The temperature here increases to about 10,000 K
• This layer radiates most of the Sun’s harmful
ultraviolet waves
– Dangerous, cancer-causing energy form
– We are protected from these by the ozone layer in
Earth’s atmosphere

11. The Corona
• This is the outermost layer of the Sun’s
atmosphere
• Extends millions of kilometers above the Sun’s
visible surface
• Creates large outer “envelope” of extremely high-
temperature and low- density gas
• The temperature here dramatically increases to
about 1,000,000 K

12. Other Solar Activity

13. Solar Wind
• A stream of charged particles is constantly being
emitted from the Sun in all directions
• This helps the planets form their magnetic fields, and
also gives comets their tails.
Original Diagram

14. Solar Prominences
• Gases from the corona & chromosphere get
trapped in giant loops of magnetic activity
• These loops extend up to 100,000 km above the
surface for days or even weeks.

15. Solar Flares
• The magnetic lines causing prominence loops can
“snap” and violently release the trapped contents
• The result is a solar flare that shoots deadly X-Rays
into interstellar space

16. Sources
• Information
– Bennett, Jeffrey, Megan Donahue, and Nicholas Schneider. The
Essential Cosmic Perspective. 6th ed. Pearson Addison-Wesley,
2012. 286-303. Print.
• Images
– Slide 1: science.nasa.gov
– Slide 5: library.thinkquest.org
– Slide 14: sciencephoto.com
– Slide 15: mnn.com