© 2010 Pearson Education, Inc. Solar Thermostat Decline in core temperature causes fusion rate to drop, so core contracts and heats up. Rise in core temperature causes fusion rate to rise, so core expands and cools down.

© 2010 Pearson Education, Inc. Clicker Question What would happen inside the Sun if a slight rise in core temperature led to a rapid rise in fusion energy? A. The core would expand and heat up slightly. B. The core would expand and cool. C. The Sun would blow up like a hydrogen bomb.

© 2010 Pearson Education, Inc. Clicker Question What would happen inside the Sun if a slight rise in core temperature led to a rapid rise in fusion energy? A. The core would expand and heat up slightly. B. The core would expand and cool. C. The Sun would blow up like a hydrogen bomb.

© 2010 Pearson Education, Inc. Energy gradually leaks out of radiation zone in form of randomly bouncing photons. How does the energy from fusion get out of the Sun?

© 2010 Pearson Education, Inc. Convection takes energy to surface. Bright blobs on photosphere show where hot gas is reaching the surface.

© 2010 Pearson Education, Inc. © 2014 Pearson Education, Inc. Patterns of vibration on the surface tell us about what is happening inside the Sun. This research is called helioseismology. Large-scale change in color from left to right reflects the sun’s rotation. How we know what is happening inside the Sun?

© 2010 Pearson Education, Inc. What causes solar activity? Sunspots, solar flares, and prominences cause solar activity. They are all related to magnetic fields.

© 2010 Pearson Education, Inc. Sunspots Temperature is 4000 K and they are cooler than other parts of the Sun’s surface. They also have strong magnetic fields.

© 2010 Pearson Education, Inc. Zeeman Effect We can measure magnetic fields in sunspots by observing the splitting of spectral lines.

© 2010 Pearson Education, Inc. Prominences often connect sunspot pairs.

© 2010 Pearson Education, Inc. Magnetic activity causes solar flares that send bursts of X rays and charged particles into space This X-ray photo is from TRACE.

© 2010 Pearson Education, Inc. Magnetic activity also causes solar prominences that erupt high above the Sun’s surface. Height is 20X Earth’s diameter!

© 2010 Pearson Education, Inc. The corona appears bright in X-ray photos, indicating its high temperature.

© 2010 Pearson Education, Inc. Coronal mass ejections send bursts of energetic charged particles out through the solar system.

© 2010 Pearson Education, Inc. The number of sunspots rises and falls in an 11-year cycle. Insert TCP 6e Figure 14.21a unannotated Insert TCP 6e Figure 14.21b unannotated