Exploring Our Sun: Size, Composition, Energy, and Layers

1. Ch 24.3: The Sun • Be able to describe the size and composition of the sun. • Explain how the sun produces energy. • Identify and define the layers of the sun.

2. How big is our star, the sun? The sun is a medium size star. 1 million earths could fit inside the sun. What is the sun made out of? The sun is about: 75% hydrogen 25% helium Our Sun

3. How old is the sun? It is 4.5 billion years old (middle-aged). Could last 10 billion years. What is the chemical composition of the sun? The sun does not have a solid surface, made of only plasma (beyond gas - PLASMA) Our Sun

4. How much of the solar system makes up the sun? The sun contains 99.8% of the solar systems mass. How does it create energy? Energy from the sun is made by nuclear fusion. Our Sun

5. This is because our Sun actually spins. (Just like our planet Earth, only much more slowly.) It takes about 27 days for the Sun to make one complete rotation. Does our Sun spin like the Earth?

6. The Layers of the Sun: • Because the sun is made of gas, no sharp boundaries exist between its various layers. Keeping this in mind, we can divide the sun into four parts: the solar interior; the visible surface, or photosphere; and two atmospheric layers, the chromosphere and corona.

7. 15 Million °C Nuclear fusion Hydrogen to Helium Core Solar Interior

8. Parts of the Sun Core

9. Radiation zone (14 – 1.5 Million °C) Convective zone (1.5 Million °C) Solar Interior

10. Parts of the Sun Radiation Zone Convective Zone Core

11. Photosphere(5,500 °C) Sphere of light Surface of the Sun What we see here on Earth. It exhibits a grainy texture called granules, produced by convection. The Visible Surface

12. Parts of the Sun Radiation Zone Convective Zone Core Photosphere

13. Chromosphere (8,000 °C) Color sphere Red in color It is a relatively thin, hot layer of incandescent gases a few thousand kilometers thick. The Atmosphere

14. Corona(1 Million °C) Outermost layer Extends for millions of kilometers Solar wind is a stream of protons and electrons ejected at high speed from the solar corona. The Atmosphere

15. Parts of the Sun Radiation Zone Convective Zone Chromosphere & Corona Core Photosphere

16. You can see the chromosphere and the corona during a total solar eclipse

18. Ch 24.3: The Sun • Be able to describe the physical features on the surface of the sun.

19. Sunspots are dark spots on the photosphere They have cooler temperatures (3,000°C) than the photosphere. Sunspots

20. Sun Spots are cooler because of magnetic fields slow down convection, less heat is transferred from the core of the sun to the photosphere Sun Spots

21. Sunspot Cycle • Sunspots vary on a 11-year cycle • At the peak of the cycle there may be more than 100 sunspots. • Also at the peak of the cycle the Sun is at its brightest.

23. Sun Spot Cycle

26. Parts of the Sun Radiation Zone Convective Zone Chromosphere & Corona Core Sunspot Photosphere

27. Sudden outward eruptions of electrically charged atomic particles During the peak in the sunspot cycle, 5 to 10 solar flares may be visible each day Solar Flares

28. Parts of the Sun Radiation Zone Convective Zone Chromosphere & Corona Core Sunspot Photosphere Solar Flare

29. Prominences are huge cloud-like arches that extend from one sunspot to another. Prominences are ionized gases trapped by magnetic fields. Prominence

30. Parts of the Sun Radiation Zone Convective Zone Chromosphere & Corona Prominence Core Sunspot Photosphere Solar Flare

33. Solar Wind • Is a constant stream of protons and electrons ejected at high speed from the sun

34. Auroras • The result of solar flares & solar wind, are bright displays of ever-changing light caused by solar radiation interacting with the atmosphere in the region of the poles.