1. Sound Waves from the Northern Lights Photo courtesy of Bjorn Jorgensen, 18 January 2005, near Tromsø, Norway http://www.spaceweather.com/aurora/images2005/17jan05/Jorgensen1.jpg Jada Maxwell

2. Coronal Mass Ejection (CME) Illustration by Steele Hill, courtesy of NASA http://sohowww.nascom.nasa.gov/localinfo/steele.html

3. Particles Spiral Down Field Lines Image: Fundamentals of Physics, 2005

4. Particles 2 Collide with atomic and molecular oxygen and nitrogen Emit energy as light Particles Spiral Down Field Lines

5. This Creates the Aurorae Image courtesy of Shawn Malone http://www.lakesuperiorphoto.com Northern Lights = Aurora Borealis Southern Lights = Aurora Australis

6. Can we hear the aurorae?  Anecdotal evidence of auroral sounds hissing, popping, crackling, swooshing corresponds with motions of light

7. 6 minutes Sound would take at least 6 minutes to travel from the aurora to the ground No recordings of audible aurorae

8. Humans can hear between 20 and 20,000 Hertz (Hz) Infrasound is below 20 Hz Currently being investigated Evidence of Infrasound from Aurorae

9. The corona of the Sun is hotter than the surface! Image: Universe, 6 th ed., 2002

10. Sound Waves on the Sun Created by Convection

11. Sound Waves Propagate through Sun’s Atmosphere Sun

12. Energy of Sound Waves is Transformed into Magnetic Waves Sun

13. Alfvén waves (s-mode) Magnetosonic waves (p-mode) Types of Magnetic Waves S-mode image courtesy of Georgia State University http://hyperphysics.phy-astr.gsu.edu/hbase/sound/tralon.html BBC animations

14. Magnetic Waves Earth

15. Transform into Sound Waves Earth

16. Beta is a Clue Beta = β = Gas Pressure Magnetic Field Pressure

17. Plasma is like… β = 1 is important

18. Mechanism for Transformation y (B 0, k) z (E 1 ) x (v 1, B 1 ) y (B 0 ) x (v 1, B 1, k) z (E 1 ) Alfvén wavesMagnetosonic waves

19. Mechanism for Transformation y (B 0, k) z (E 1 ) x (v 1, B 1 ) y (B 0 ) x (v 1, B 1, k) z (E 1 ) Alfvén waves to Acoustic waves Magnetosonic waves to Acoustic waves v 1 p E 1 p

20. When Beta = 1 β = 1 in Earth’s atmosphere?

21. CMEs Aurorae MHD Waves Infrasound ? observed What have we learned?

22. Future Plans Gather data from satellite observations of resonant acoustic and Alfvén waves in a single CME induced geomagnetic event Evaluate how wave velocities, frequencies and wavelengths change as altitude and β changes Use data of auroral infrasound observed at Earth’s surface to extrapolate speeds in the ionosphere and compare to magnetic wave speeds

23. Image Sources: ▪ NASA http://sohowww.nascom.nasa.gov/localinfo/steele.html ▪ Shawn Malone http://www.lakesuperiorphoto.com ▪ Halliday/Resnick/Walker. Fundamentals of Physics, John Wiley & Sons, 2005, p 746 http://academic.evergreen.edu/m/maxjad02 Website: