1. Unit 5

2. Lesson 5-1 What is the Sun?

3. I.Stars A.Star – huge sphere/ball of hot gases B.The Sun – star at center of solar system 1.looks like a large ball of light 2.Medium sized star made of hydrogen & helium 3.Source of most energy on Earth 4.Responsible for wind/weather on Earth

4. C.Ways to classify stars: 1.color – blue, white, yellow, orange, red a.blue – hottest b.red – coolest 2.brightness – a.how far from Earth – closest (sun) brightest b.size of star – sun is average D.Sun is larger than anything else in solar system

5. II.Features of the Sun A.Layers of the sun (from inside out) 1.Core – The very center where fusion takes place creating energy. (heat and light) Most of the Sun’s mass is here. 2.Radiation Zone – The largest area. Heat travels outward from the core.

6. 3.Convection Zone – Heat swirls around. It cools off near the surface and falls towards the radiation zone. Then it heats back up and rises to the surface. 4. Photosphere – (circle of light) This is the outer visible surface of the sun. Itcontains many unique features. 5.Corona / Chromosphere – The atmosphere around the sun. Its outer glow which is only visible during an eclipse. http://nexus.polaris.net/services/image- archive/space/sol//eclip91e.jpg

7. B. Features of the Sun’s Surface 1.Granules – bright hot areas 2.Sun Spots – dark cool areas 3.Solar Flares - bursts of energy that stretch from the sun

8. III.How the Sun Produces Energy A.The Sun makes energy by fusion. 1.Hydrogen molecules (H2) smash together to make helium (He) and energy. B.Energy travels to the Earth in Waves. 1.There are many different kinds of waves. 2.Visible light is the set of waves in the middle. (ROY G BIV)

9. C.Energy waves from Low to High: (Less energy to more energy 1)Radio Waves 2)Microwaves 3)Infrared waves 4)Visible light 5)Ultraviolet 6)X-Rays 7)Gamma Rays