Halley's Comet and Cholera

John Green reviews Halley's Comet, a celestial body visible from Earth once in a lifetime, and cholera, an infection caused by bacteria and people. Thanks to audible for sponsoring today's episode: http://audible.com/anthro Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.See Privacy Policy at https://art19.com/privacy and California Privacy Notice at https://art19.com/privacy#do-not-sell-my-info.