The Sun is An Active Place!

1. The Sun is An Active Place! …Yes it is…

2. The Sun • The sun is a very dynamic (active) place • Nuclear Fusion in the core of the sun produces huge amounts of Energy • This Heat Energy rises to the surface because of convection (think density) • As hot material reaches the surface of the sun gasses boil and erupt on surface

3. Sun Spots • The Sun’s magnetic field slows down the “boiling” on the photosphere (surface) of the sun • This causes areas on the sun to be slightly cooler than the surrounding areas. • These cooler spots are Sunspots • Sunspots = cool dark regions on the sun

4. Sunspots, Galileo Found Them • Before the invention of the telescope, the Sun was thought to be a perfect disk.   However as soon as telescopes became available, astronomers turned them to the Sun.   • They discovered two things…Sunspots and blindness.  • Not Galileo though. He observed only at sunset and sunrise and by projecting the light onto a screen rather than trying to look through the telescope itself.   He drew his results very carefully: • Here’s one of his drawings from 1612. Sunspots

5. Sunspots • Sunspots and their location on the sun move in a cycle of low to high activity.

6. Sunspot Cycles • The Number of sunspots changes from year to year. • How many in Jan 2001? • How many right now? Year

7. The number of sunspots increases and decreases in cycles that last from 6-17 years (averaging 11 years). • Solar flares accompany increases in sunspot activity. • What’s the Max we’ve observed?______ • View d:/The Sun/Sunspots

8. Other Activity on the Sun • Solar Flares = Giant storms on the surface of the sun • Up to 5,000,000°C • They send out streams of charged particles from the sun.

9. Solar Flares • Solar Flares can reap havoc on Earth! • As emissions from the sun encounter Earth, they can ignite geomagnetic storms. • These geomagnetic storms can cause: • electrical power outages • damage to communication satellites • radio communications disturbance

10. Increased solar emissions can also lead to a higher frequency of auroras aka the Northern Lights clip

11. There is evidence that Earth’s climate is effected by the solar activity cycle. • Three dimensional images of the sun by space crafts such as the STEREO, have greatly enhanced our ability to follow solar storms and forecast arrival time to Earth.

12. So where’s all this Heat Energy coming from??

13. “That’s Hot” Nuclear Fusion • “I’m glad you asked, Paris… Nuclear Fusion is why the sun is sizzlin’ hot.” • The Sun is about 70% hydrogen and 28% helium and 2% metals. • This changes slowly over time as the Sun converts hydrogen to helium in its core. Random fact Each second about 700,000,000 tons of hydrogen are converted to about 695,000,000 tons of helium

14. Fusion Nuclear Fusion = The process by which 2 or more nuclei (Hydrogen) join together or fuse. This takes a huge amount of Energy because same charged nuclei repel each other When they do this a larger more massive nucleus is made (Helium). During this process Energy is produced in the form of Light. View d:The Sun/fusion

15. Fusion, FYI • Fusion (the combining of the Nuclei of elements) is how all Elements found in the Universe are created. • If it exists, it’s because of fusion. • Humans can do this somewhat unsuccessfully and for short amounts of time

16. The Solar Wind • In addition to heat and light, the Sun also emits a low density stream of charged particles (mostly electrons and protons) known as the solar wind which propagates throughout the solar system at about 450 km/sec.

17. The Solar Wind • The solar wind moves outward from the sun in a pinwheel shaped spiral pattern in a more or less steady flow.

18. The Solar Wind • Recent data from the spacecraft Ulysses show that during the minimum of the solar cycle the solar wind emanating from the polar regions flows at nearly double the rate, 750 kilometers per second, than it does at lower latitudes. The composition of the solar wind also appears to differ in the polar regions. During the solar maximum, however, the solar wind moves at an intermediate speed. • Further study of the solar wind will be done by the recently launched Wind, ACE and SOHO spacecraft from the dynamically stable vantage point directly between the Earth and the Sun about 1.6 million km from Earth. • The solar wind has large effects on the tails of comets and even has measurable effects on the trajectories of spacecraft.

20. E5.2e Explain how the Hertzsprung-Russell (H-R) diagram can be used to deduce other parameters (distance). • Clarification: Brightness and color can be determined given the location of a star on the H-R diagram • E5.2f Explain how you can infer the temperature, life span, and mass of a star from its color. Use the H-R diagram to explain the life cycles of stars. Clarification: The Hertzsprung-Russell diagram illustrates the relationship between the absolute magnitude and the surface temperature of stars. As stars evolve, their position on the Hertzsprung-Russell diagram moves. The temperature of a star is directly related to the color of a star. • E5.2g Explain how the balance between fusion and gravity controls the evolution of a star (equilibrium • E5.2h Compare the evolution paths of low, moderate and high mass stars using the H-R diagram. • after a solar storm emission.

21. auroras • Hertzsprung-Russell (H-R) diagram • life cycle of stars • nuclear fusion • nuclear reactions • power disturbances • radio and satellite communication • release of energy • solar energy • solar flares • solar wind • source of chemical elements • spontaneous nuclear reaction • star composition • star destruction • star equilibrium • star formation • star system • star temperature • star size • star types • stellar energy • sunspot cycle • stellar evolution

22. iii. Enrichment • CE: E5.2A • Analyze the solar activity from the past 100 years and predict the impact over the next 50 years if the pattern were to proceed at the same rate. Explore the data for patterns in several ways such as segmenting time frames and averaging the number of peaks. • iv. General • CE: E5.2A • Construct a table of sunspot activity and plot the points in order to make predictions about the solar cycle and possibility of disturbances to Earth’s system. Look for patterns in the data to determine how predictable sun spot activity is. • v. Intervention • CE: E5.2A • Using records of sunspot activity calculate the average solar cycle length and use that data to predict future solar maximums. Calculate and graph the number of years between the peaks and valleys.

23. Real World Context: • The origin of elements involves the formation of Hydrogen and Helium in the early universe followed by the formation of heavier elements. • Exclusions • Details of nuclear fusion • Reaction rates in stars • Instruments, Measurement, and Representations • Telescopes and binoculars to see stars, nebulae, and galaxies • Computer simulations of processes in stars • Images taken by large or space based telescopes • Spectra of stars and galaxies • Graphs that depict the relationships of astronomic variables (e.g., brightness versus temperature, distance to galaxies versus redshift) • Diagrams and Models showing a cross-section of the Sun and the evolution of stars • If Time: • Investigate the risk of radiation exposure during air travel