A monitoring system developed to listen for secret nuclear tests mostly hears other events happening all around Earth.

Thanks to CTBTO for sponsoring this video: www.ctbto.org

Thanks also to our supporters on https://www.patreon.com/MinuteEarth

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FYI: We try to leave jargon out of our videos, but if you want to learn more about this topic, here are some keywords to get your googling started:

• Infrasound: sound waves too low in frequency for humans to hear. The CTBTO stations detect frequencies of 0.02 to 4Hz
• Hydroacoustic: having to do with underwater sounds. The CTBTO stations detect frequencies of 1-100 Hz
• Seismic: oscillation waves in the earth, often caused by earthquakes or other tectonic activity. The CTBTO stations detect frequencies of 0.02-16 Hz

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Credits (and Twitter handles):

Script Writer: Alex Reich

Script Editor: Kate Yoshida (@KateYoshida)

Video Illustrator: Jesse Agar

Video Director: Kate Yoshida (@KateYoshida)

Video Narrator: Kate Yoshida (@KateYoshida)

With Contributions From: Henry Reich, Ever Salazar, Emily Elert, Peter Reich, David Goldenberg

Music by: Nathaniel Schroeder: http://www.soundcloud.com/drschroeder

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If you liked this week’s video, we think you might also like:

Animals can detect infrasound: http://www.slate.com/articles/news_and_politics/explainer/2004/12/surviving_the_tsunami.html

A Time-Lapse Map of Every Nuclear Explosion Since 1945: https://www.youtube.com/watch?v=LLCF7vPanrY

Sound travels 1000s of miles in the ocean’s SOFAR channel: https://en.wikipedia.org/wiki/SOFAR_channel

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References:

Sounds in the video that were recorded by CTBTO stations:

0:32    Kasatoshi volcano eruption in August 2008, detected 2100km away at infrasound station on mainland Alaska. Sped up 500x https://en.wikipedia.org/wiki/Kasatochi_Island

0:35    Explosion of Antares rocket in October 2014, detected 1100km away at Bermuda infrasound station. Sped up 150x https://en.wikipedia.org/wiki/Cygnus_CRS_Orb-3 and video: https://en.wikipedia.org/wiki/File:Antares_Fails_to_Reach_Orbit_with_Cygnus_CRS-3_after_Rocket_Explodes.webm

0:37    Ship engine detected June 1 2017 by hydroacoustic station. Sped up 16x

0:40    Waves hitting an iceberg and causing it to vibrate like a cymbal in July 2010. Detected by hydroacoustic station off of Western Australia. Sped up 16x

1:01    Whale call Feb 18 2017, detected by hydroacoustic station. Sped up 16x

1:08    Chelyabinsk meteor airburst February 15 2013, detected by infrasound station 650km away in Kazakhstan. Sped up 135x

1:39    Earthquake Jan 2 2017, detected by infrasound station. Sped up 16x

2:00    Sound with unknown cause, detected by hydroacoustic station. March 25 2017. Sped up 16x



References

Brown, P. G., et al. 2013. A 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors. Nature, 503(7475), 238-241. http://dx.doi.org/10.1038/nature12741

Graham, G. May 2017, Personal communication

Harabalus, G. May 2017, personal communication

LeBras, R. May 2017, personal communication

Mialle P., May 2017, personal communication

Miksis-Old, J. May 2017, personal communication

Nielsen, P., May 2017, personal communication

Le Pichon, A., et al. 2013. The 2013 Russian fireball largest ever detected by CTBTO infrasound sensors. Geophysical Research Letters, 40(14), 3732-3737. http://onlinelibrary.wiley.com/doi/10.1002/grl.50619/full

Check out our new website! https://www.minuteearth.com/
Thanks to Squarespace for sponsoring this video. http://www.squarespace.com/minuteearth

Thanks also to our supporters on https://www.patreon.com/MinuteEarth

Astringent plant chemicals called tannins bind proteins on mucous membrane and skin, generating a prickly, puckery mouthfeel from foods and letting us “tan” skins into leather.
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If you want to learn more about this topic, start your googling here:
Tannin: a yellow or brownish chemical present in some plant tissues, used in leather production and ink manufacture, and a contributor to the sensation of astringency Astringency: the sensation caused by the contraction of body tissues due to tannins, often called “mouthfeel” Polyphenol: a chemical compound containing more than one phenolic hydroxyl group, of which tannins are a major group Phenolic: a chemical compound with a hydroxyl group (oxygen & hydrogen) linked directly to a benzene ring
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Credits (and Twitter handles):
Script Writer: Alex Reich (@alexhreich)
Script Editor: Kate Yoshida (@KateYoshida)
Video Illustrator: Ever Salazar (@eversalazar)
Video Director: Henry Reich (@MinutePhysics)
Video Narrator: Emily Elert (@eelert)
With Contributions From: Peter Reich, David Goldenberg
Music by: Nathaniel Schroeder: http://www.soundcloud.com/drschroeder

_________________________________________

Like our videos?
Subscribe to MinuteEarth on YouTube: http://goo.gl/EpIDGd
Support us on Patreon: https://goo.gl/ZVgLQZ

And visit our new website! https://www.minuteearth.com/

Also, say hello on:
Facebook: http://goo.gl/FpAvo6
Twitter: http://goo.gl/Y1aWVC

And find us on itunes: https://goo.gl/sfwS6n

___________________________________________

References:

Bajec, M. R., & Pickering, G. J. 2008. Astringency: mechanisms and perception. Critical reviews in food science and nutrition, 48(9), 858-875. https://goo.gl/XLR0JY

Barbehenn, R. V., & Constabel, C. P. 2011. Tannins in plant–herbivore interactions. Phytochemistry, 72(13), 1551-1565. http://www.sciencedirect.com/science/article/pii/S0031942211000690

Covington, A. D. 1997. Modern tanning chemistry. Chemical Society Reviews, 26(2), 111-126. http://pubs.rsc.org/en/content/articlehtml/1997/cs/cs9972600111

Covington, A. D. 2009. Tanning chemistry: the science of leather. Royal Society of Chemistry.

Covington, A., Mar 2017, personal communication.

Gawel, R. 1998. Red wine astringency: a review. Australian Journal of Grape and Wine Research, 4(2), 74-95. http://onlinelibrary.wiley.com/doi/10.1111/j.1755-0238.1998.tb00137.x/full

Lesschaeve, I. & A.C. Noble. 2005. Polyphenols: factors influencing their sensory properties and their effects on food and beverage preferences. The American journal of clinical nutrition 81, no. 1: 330S-335S. http://ajcn.nutrition.org/content/81/1/330S.full

Siebert, K., Mar 2017, personal communication.