In 1908, on a sunny, clear, quiet morning in Siberia, witnesses recall seeing a blinding light streak across the sky, and then… the earth shook, a forest was flattened, fish were thrown from streams, and roofs were blown off houses. The “Tunguska event,” as it came to be known, was one of the largest extraterrestrial impact events in Earth’s history. But what kind of impact—what exactly struck the earth in the middle of Siberia?—is still up for debate. Producer Annie McEwen dives into one idea that suggests a culprit so mysterious, so powerful, so… tiny, you won’t believe your ears. And stranger still, it may be in you right now. Or, according to Senior Correspondent Molly Webster, it could be You.EPISODE CREDITS Reported by - Annie McEwen and Molly WebsterProduced by - Annie McEwen and Becca Bresslerwith help from - Matt KieltyOriginal music and sound design contributed by - Jeremy Bloom, Annie McEwen, Matt KieltyMixing by - Jeremy Bloomwith dialogue mixing by - Arianne WackFact-checking by - Diane Kellyand edited by  - Alex Neason GUESTS Matt O’Dowd (https://www.mattodowd.space/)Special Thanks:  Special thanks to, Matthew E. Caplan, Brian Greene, Priyamvada Natarajan, Almog Yalinewich EPISODE CITATIONS Videos: Watch “PBS Space Time,” (https://zpr.io/GNhVAWDday49) the groovy show and side-gig of physicist and episode guest Matt O’Dowd Articles: Read more (https://zpr.io/J4cKYG5uTgNf) about the Tunguska impact event! Check out the paper (https://zpr.io/vZxkKtGQczBL), which considers the shape of the crater a primordial black hole would make, should it hit earth: “Crater Morphology of Primordial Black Hole Impacts”Curious to learn more about black holes possibly being dark matter? You can in the paper (https://zpr.io/sPpuSwhGFkDJ), “Exploring the high-redshift PBH- ΛCDM Universe: early black hole seeding, the first stars and cosmic radiation backgrounds”   Books:  Get your glow on – Senior Correspondent Molly Webster has a new kids book, a fictional tale about a lonely Little Black Hole (https://zpr.io/e8EKrM7YF32T) Our newsletter comes out every Wednesday. It includes short essays, recommendations, and details about other ways to interact with the show. Sign up (https://radiolab.org/newsletter)! Radiolab is supported by listeners like you. Support Radiolab by becoming a member of The Lab (https://members.radiolab.org/) today. Follow our show on Instagram, Twitter and Facebook @radiolab, and share your thoughts with us by emailing radiolab@wnyc.org. Leadership support for Radiolab’s science programming is provided by the Gordon and Betty Moore Foundation, Science Sandbox, a Simons Foundation Initiative, and the John Templeton Foundation. Foundational support for Radiolab was provided by the Alfred P. Sloan Foundation.

Extragalactic astrophysicist and host of PBS Space Time, Matt O'Dowd, discusses supermassive black holes, Planck lengths, and the gravitational wave background. Topics include falling into a black hole, exploring supermassive black holes, gravitational lenses, dark energy mysteries, and cosmic expansion. The conversation delves into the limits of measuring space distances and the endless possibilities of human inquiry into the cosmos.

Can we use gravitational lensing to view distant planets? Neil deGrasse Tyson and comedian Chuck Nice explore black holes, quasars, entropy, and more with astrophysicist and host of PBS Space Time, Matt O’Dowd.NOTE: StarTalk+ Patrons can listen to this entire episode commercial-free.Thanks to our Patrons Kelly Madison, Shaun Moats, Vascked, Irene Campbell, Joseph Brown, and Guillermo Leal for supporting us this week.Photo Credit: NOIRLab/NSF/AURA/J. da Silva, CC BY 4.0, via Wikimedia Commons Subscribe to SiriusXM Podcasts+ to listen to new episodes of StarTalk Radio ad-free and a whole week early.Start a free trial now on Apple Podcasts or by visiting siriusxm.com/podcastsplus.