Why is Indigo in the Rainbow?

Indigo may be a very vague and unnecessary color, but it has an interesting history that involves some plants, turmoil, and Isaac Newton s interest in the number seven. Hosted by: Hank Green ---------- Support SciShow by becoming a patron on Patreon: https://www.patreon.com/scishow ---------- Dooblydoo thanks go to the following Patreon supporters -- we couldn t make SciShow without them! Shout out to Justin Ove, Accalia Elementia, Kathy & Tim Philip, Kevin Bealer, Justin Lentz, Fatima Iqbal, Thomas J., Chris Peters, Tim Curwick, Lucy McGlasson, Andreas Heydeck, Will and Sonja Marple, Mark Terrio-Cameron, Charles George, Christopher Collins, and Patrick D. Ashmore. ---------- Like SciShow? Want to help support us, and also get things to put on your walls, cover your torso and hold your liquids? Check out our awesome products over at DFTBA Records: http://dftba.com/scishow ---------- Looking for SciShow elsewhere on the internet? Facebook: http://www.facebook.com/scishow Twitter: http://www.twitter.com/scishow Tumblr: http://scishow.tumblr.com Instagram: http://instagram.com/thescishow ---------- Sources: http://www.npr.org/2011/11/07/142094103/indigo-the-indelible-color-that-ruled-the-world http://www.theatlantic.com/video/index/283432/why-roygbiv-is-arbitrary/ http://www.popsci.com/blog-network/techtiles/problem-indigo http://www1.umn.edu/ships/updates/newton1.htm http://www.npr.org/books/titles/142094203/indigo-in-search-of-the-color-that-seduced-the-world#excerpt http://www.nytimes.com/2015/11/06/fashion/mens-style/levis-denim-lab-san-francisco.html http://www.nytimes.com/2014/08/07/garden/reviving-a-dyeing-technique.html http://www.wildcolours.co.uk/html/indigo_history.html http://news.nationalpost.com/news/why-the-colour-indigo-is-disappearing-from-sir-isaac-newtons-occult-rainbow http://health.howstuffworks.com/mental-health/human-nature/perception/eye3.htm http://science.howstuffworks.com/colors-in-visible-light-spectrum.htm https://books.google.com/books?id=PbsoAXWbnr4C&pg=PA193&dq=Newton+color+Indigo&hl=en&ei=kw3QTemzJsea8QOC_anbDQ&sa=X&oi=book_result&ct=result&resnum=7&ved=0CH0Q6AEwBg#v=onepage&q=Newton%20color%20Indigo&f=false Image Sources: https://commons.wikimedia.org/wiki/File:Indigofera_tinctoria1.jpg https://commons.wikimedia.org/wiki/File:COLLECTIE_TROPENMUSEUM_Indigo_wordt_aangemaakt_in_kuilen_in_uitgehakte_puimsteentufgrond_Karolanden_TMnr_10014190.jpg https://commons.wikimedia.org/wiki/File:Indigo_cake.jpg https://commons.wikimedia.org/wiki/File:Indigo_plant_extract_sample.jpg https://commons.wikimedia.org/wiki/File:Indo-Roman_trade.jpg https://commons.wikimedia.org/wiki/File:Indigoproduktion_BASF_1890.JPG https://commons.wikimedia.org/wiki/File:GodfreyKneller-IsaacNewton-1689.jpg https://commons.wikimedia.org/wiki/File:NewtonDualPrismExperiment.jpg https://commons.wikimedia.org/wiki/File:Newton%27s_colour_circle.png https://en.wikipedia.org/wiki/File:S_Club_7_-_Bournemouth_2015.jpg