Sound Waves from Aurora Borealis.


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Sound Waves from the Northern Lights. Photograph politeness of Bjorn Jorgensen, 18 January 2005, ... Sound would take no less than 6 minutes to head out from the aurora to the ground ...
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Slide 1

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

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

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

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Particles Spiral Down Field Lines Particles 2 Collide with nuclear and sub-atomic oxygen and nitrogen Emit vitality as light

Slide 5

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

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Can we hear the aurorae? Recounted confirmation of auroral sounds murmuring, popping, crackling, swooshing compares with movements of light

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6 minutes Sound would take no less than 6 minutes to make a trip from the aurora to the ground No recordings of perceptible aurorae

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Evidence of Infrasound from Aurorae Humans can hear somewhere around 20 and 20,000 Hertz (Hz) Infrasound is beneath 20 Hz Currently being examined

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The crown of the Sun is more sweltering than the surface! Picture: Universe, 6 th ed., 2002

Slide 10

Sound Waves on the Sun Created by Convection

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Sound Waves Propagate through Sun\'s Atmosphere Sun

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Energy of Sound Waves is Transformed into Magnetic Waves Sun

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

Slide 14

Magnetic Waves Earth

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Transform into Sound Waves Earth

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

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Plasma resemble… β = 1 is critical

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

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

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β = 1 in Earth\'s environment? At the point when Beta = 1

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What have we learned? MHD Waves ? watched CMEs Infrasound watched Aurorae

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Future Plans Gather information from satellite perceptions of resounding acoustic and Alfvén waves in a solitary CME actuated geomagnetic occasion Evaluate how wave speeds, frequencies and wavelengths change as height and β changes Use information of auroral infrasound saw at Earth\'s surface to extrapolate speeds in the ionosphere and contrast with attractive wave speeds

Slide 23

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

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