What is a rainbow? An optical illusion? Or a thing out there in the world? For centuries, cultures around the world believed that rainbows were bridges - pathways to gods and to the afterlife. Then in 1665, during a plague, a young Isaac Newton made a discovery that changed everything : sunlight is made of many colors. He counted 7. But artists, poets and curious children weren’t convinced. How could a rainbow only have seven colors? Their skepticism led to a far stranger discovery that would revolutionize how we understand the universe. - In the end, we learn that rainbows are kind of a bridge - between our outer and inner worlds.

Science writer Philip Ball helps us follow the rainbow’s story, plus Songbud and the Youth Pride Chorus of New York City turn it all into a magical musical.

To learn more about the history of color, read Dr. Ball’s book Bright Earth.

Special thanks to Philip Ball, the Youth Pride Chorus of NYC, Nicholas Sienkiewicz and Rashad Chambers.

In more exciting news, we just created the first ever Terrestrials Jigsaw Puzzle! It’s a scene of all the creatures we’ve featured on Terrestrials so far, made by artist Arthur Jones. It can be yours for the simple price of supporting Terrestrials by joining our brand new Explorers Club! You get all types of perks like extra Alan songs, ad-free listening and this puzzle for the month of December! Visit TerrestrialsPodcast.org/donate. Thank you for all your support.

Terrestrials was created by Lulu Miller with WNYC. This episode was produced by Tanya Chawla and Ana González, with technicolor sound design by Mira Burt-Wintonick. Sarah Sandbach is our Executive Producer. Our team also includes Alan Goffinski and Joe Plourde. Factchecking by Diane Kelly.

Support for Terrestrials is provided by the Simons Foundation, the Arthur Vining Davis Foundations, and the John Templeton Foundation.

A reminder that Terrestrials also makes original music! You can find ‘Rainbows! The Bridge EP’ and all other music from the show here.

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The Bridge: How Rainbows Connect Worlds

Radiolab for Kids