Comet 2I/Borisov will reach its closest approach to the sun on December 8, 2019. We talk to planetary astronomer Michele Bannister about where the heck this comet came from, and what it tells us about our galaxy. Follow Maddie on Twitter — she's @maddie_sofia). And email the show at [email protected]).Learn more about sponsor message choices: podcastchoices.com/adchoices)NPR Privacy Policy)
