Sound Waves
From the
Northern
Lights
Jada Maxwell
Photo courtesy of Bjorn Jorgensen, 18 January 2005, near Tromsø, Norway
http://www.spaceweather.com/aurora/images2005/17jan05/Jorgensen1.jpg
“Synergy means behavior of
whole systems unpredicted by the
behavior of their parts taken
separately.”
- Buckminster Fuller
Can magnetic waves in the aurorae
transform into sound waves?
 What creates the aurora?
 Sound waves from the aurora
 Wave transformation on the Sun
 Beginning to answer my question
What creates the aurora?
The aurora is created by a chain of events,
beginning
with energy
from the sun.
Chain
of Events
Image courtesy of Tom Michalik
http://faculty.rmwc.edu/tmichalik/solarwind.htm
The Magnetosphere
Image courtesy of Minnesota Technolog
http://technolog.it.umn.edu/technolog/novdec97/cover.htm
Coronal Mass Ejection (CME)
Illustration by Steele Hill, courtesy of NASA
http://sohowww.nascom.nasa.gov/localinfo/steele.html
South-North Magnetic Orientation
of CME
North-South Magnetic Orientation
of CME
Magnetic Reconnection
on Dayside of Earth
Magnetic Field Lines are Drawn
Back to Magnetotail
Magnetotail is Compressed
Magnetic Reconnection in
Magnetotail
Particles Spiral Down Field Lines
Image: Fundamentals of Physics, 2005
Particles Spiral Down Field Lines
Particles 2
 Collide with atomic and molecular
oxygen and nitrogen
 Emit energy as light
This Creates
the Aurorae
 Northern Lights =
Aurora Borealis
 Southern Lights =
Aurora Australis
Image courtesy of Shawn Malone
http://www.lakesuperiorphoto.com
Nearly Mirror Images
Aurora Borealis
Images courtesy of NOAA
http://sec.noaa.gov/pmap/
Aurora Australis
Can we hear the aurorae?
 Anecdotal evidence of auroral sounds
• hissing, popping, crackling,
swooshing
• corresponds with motions of
light
6 minutes

Sound would take at least 6
minutes to travel from the
aurora to the ground

No recordings of audible
aurorae
Explanations of Audible Sounds
 Psychological
 Freezing Breath
 “Brush discharge”
Evidence of Infrasound from
Aurorae
 Humans can hear between 20
and 20,000 Hertz (Hz)
 Infrasound is below 20 Hz
 Currently being investigated
 Gas expansion
The Sun Creates Sound Waves
Sound Waves on the Sun
Created by Convection
Sound Waves Propagate through
Sun’s Atmosphere
Sun
Energy of Sound Waves is
Transformed into Magnetic Waves
Sun
Types of Magnetic Waves
 Alfvén waves (s-mode)
 Magnetosonic waves (p-mode)
BBC animations
Images courtesy of Georgia State University
http://hyperphysics.phy-astr.gsu.edu/hbase/sound/tralon.html
My Question
Can magnetic waves in
the aurorae transform
into sound waves?
Magnetic Waves
Earth
Transform into Sound Waves
Earth
Finding Beta
Beta = β =
Gas (atmospheric) Pressure
Magnetic Field Pressure
β=1?
Resonance
 All material has a frequency that it
vibrates at
 Matching the frequency allows the
material to absorb energy
 Singing wine glass
Resonance in the Aurora
When β = 1,
 Energy from magnetic
waves can be transferred to
the atmosphere
 Found the right frequency
When Beta = 1
β=1?
 At 120 km
 Near bottom of aurorae
More Questions to Investigate
 How does
β vary?
 Compare gas expansion theory to
wave transformation
 How much might Alfvén and
magnetosonic waves each
contribute to this effect?
 Which is more likely to transform?
Thanks to:
 Dr. E.J. Zita for her guidance
and helpful discussions
 Beth Stinson for instruction
in PowerPoint
Image Sources:
▪ NOAA (National Oceanic & Atmospheric Administration)
http://sec.noaa.gov/pmap/
▪ NASA
http://sohowww.nascom.nasa.gov/localinfo/steele.html
▪ SpaceWeather.com
http://www.spaceweather.com/aurora/images2005.htm
▪ Shawn Malone
http://www.lakesuperiorphoto.com
▪ Tom Michalik
http://faculty.rmwc.edu/tmichalik/solarwind.htm
▪ Minnesota Technolog
http://technolog.it.umn.edu/technolog/novdec97/cover.htm
▪ Fundamentals of Physics, Halliday/Resnick/Walker, John Wiley
& Sons, 2005, p 746