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: ---------- 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., Ch