Ep. 775: The Hydrogen 21-cm Line

Streamed live on Dec 15, 2025. Atomic hydrogen is the raw material for stars, but there’s a problem. It’s cold & dark, but it can do a very rare trick, releasing a photon in a very specific wavelength, known as the 21 centimeter line. And thanks to this wavelength astronomers have mapped out star forming regions across the Milky Way, the Universe and into the Dark Ages! This forbidden transition of Hydrogen has led to the mapping of galaxy rotation, a cool classroom application of quantum mechanics, and weirdly no Nobel prize. In this episode, Fraser and Pamela take a look at this line's out-of-proportion awesomeness!   This show is supported through people like you on Patreon.com/AstronomyCast   In this episode, we'd like to thank: Andrew Poelstra, BogieNet, Brian Cagle, Burry Gowen, David, David Rossetter, Ed, Gerhard Schwarzer, Jason Kwong, Jeanette Wink, Michael Purcell, Sergey Manouilov, Siggi Kemmler, Sérgio Sancevero

Hosted by: Fraser Cain and Dr. Pamela L. Gay. Streamed live on Nov 8, 2025. [Editor's Note: Fraser says "Episode 773" at the head of the show. Not to worry, he was just confused. They recorded a few episodes out of sequence. I fixed the issue in the regular non-FullRaw episode.] Scientific expertise is under attack on all fronts with concerns coming from politicians and the public. While most of this is unwarranted and politically motivated, there can be germ of truth. Bad science does happen, but how? How is it that papers that very few believe still make it through peer review and to publication? Why do professors at prominent universities get quoted saying things that seem to be fiction? In this episode, we consider the case for letting potentially impossible things make it to publication.    This show is supported through people like you on Patreon.com/AstronomyCast    In this episode, we'd like to thank: Andrew Poelstra, BogieNet, Brian Cagle, Burry Gowen, David, David Rossetter, Ed, Gerhard Schwarzer, Jason Kwong, Jeanette Wink, Michael Purcell, Sergey Manouilov, Siggi Kemmler, Sérgio Sancevero

Hosted by: Fraser Cain and Dr. Pamela L. Gay. Streamed live on Nov 9, 2025. We are powerless fans of space exploration. But what if some fool gave us the authority and funding to make our space dreams a reality? Someone asked us what we’d do with a billion dollars. What missions? Which telescopes? But what if we had more? 100 Billion! A trillion! All the monies! You keep asking, and this week we answer you! Come hear what Fraser and Pamela would do if they were given complete control over $1billion that had to be used for astronomy.    This show is supported through people like you on Patreon.com/AstronomyCast    In this episode, we'd like to thank: Andrew Poelstra, BogieNet, Brian Cagle, Burry Gowen, David, David Rossetter, Ed, Gerhard Schwarzer, Jason Kwong, Jeanette Wink, Michael Purcell, Sergey Manouilov, Siggi Kemmler, Sérgio Sancevero

Hosted by: Fraser Cain and Dr. Pamela L. Gay. Streamed live on Nov 9, 2025. It’s time once again for our annual gift giving guide. We’ve got recommendations for books, movies, TV shows, games and of course astronomy gear to satisfy the space nerds in your family. The Christmas season is almost upon us, and with it comes excuses to inject science into the lives of those you love... or ask for them to give you that book, lens, or art print you already know you'll love. In this episode, Fraser and Pamela share the things they think would make good gifts for nerds like us.    This show is supported through people like you on Patreon.com/AstronomyCast   In this episode, we'd like to thank: Andrew Poelstra, BogieNet, Brian Cagle, Burry Gowen, David, David Rossetter, Ed, Gerhard Schwarzer, Jason Kwong, Jeanette Wink, Michael Purcell, Sergey Manouilov, Siggi Kemmler, Sérgio Sancevero

Streamed live on Nov 8, 2025. With the arrival of the comet 3I/Atlas (Asteroid Terrestrial-impact Last Alert System), the world is getting a crash course in comets, their behavior, and of course their tails. Today we’re going to talk about comets and their tails, why they exist, how they grow, why they can be different colors and how they can be sometimes point AT the Sun.   Comets are one of the most animated and ephemeral targets for astronomy. From night to night they can change in shape and color, and every nuance tells us something. In this episode, we decode blue tails, green cores, forward-facing plumes, and other weird and awesome details observed with these icy visitors.    This show is supported through people like you on Patreon.com/AstronomyCast   In this episode, we'd like to thank: Andrew Poelstra, BogieNet, Brian Cagle, Burry Gowen, David, David Rossetter, Ed, Gerhard Schwarzer, Jason Kwong, Jeanette Wink, Michael Purcell, Sergey Manouilov, Siggi Kemmler, Sérgio Sancevero

Streamed live on Nov 3, 2025. Hosted by: Fraser Cain and Dr. Pamela L. Gay. It is arguable that humanity now has the technological ability to live on Mars. It would be done at enormous expense and sacrifice, and there are some tricky problems that we haven’t solved yet. Although we could live on Mars, should we? There is a famous quote from Jurassic Park: "Your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should." This concept is played out across the sciences, and in planetary exploration, it requires us to ask, all because we can launch humans toward Mars, should we?   This show is supported through people like you on Patreon.com/AstronomyCast In this episode, we'd like to thank: Andrew Poelstra, BogieNet, Brian Cagle, Burry Gowen, David, David Rossetter, Ed, Gerhard Schwarzer, Jason Kwong, Jeanette Wink, Michael Purcell, Sergey Manouilov, Siggi Kemmler, Sérgio Sancevero

Streamed live on Oct 20, 2025. New instruments bring new mysteries, and when James Webb came on line it uncovered a collection of strange, compact, bright objects shifted deeply into the red end of the spectrum. These were dubbed “Little red dots” or LRDs. And the astronomical community continues to puzzle over what they are. When JWST first peered into the distant past, it discovered the early universe had a rash of little red dots. Their existence just 450 million years after the big bang meant either galaxies were forming way faster than anyone predicted, or something unimagined had been found.    This show is supported through people like you on Patreon.com/AstronomyCast  In this episode, we'd like to thank: Andrew Poelstra, BogieNet, Brian Cagle, Burry Gowen, David, David Rossetter, David Truog, Ed, Gerhard Schwarzer, Jason Kwong, Jeanette Wink, Michael Purcell, Olger, Sergio Sancevero, Sergey Manouilov, Siggi Kemmler, Stephen Veit

Streamed live on Oct 13, 2025. So it’s been decades since we’ve seen a bright comet in the sky. And actually there was a pair — Hale-Bopp and Hyakutake. And then, silence! And unmet promises by the Universe to give us a bright comet. Comets are unpredictable, and they arrive precisely when they intend to. Is it time again for a bright comet? If you asked us in January if 2025 was going to have any outstanding comets would fly through the Solar System, we would have (and we did) say "no." And we were wrong. Comets are fickle, unpredictable, and like to do exactly what we didn't predict.   This show is supported through people like you on Patreon.com/AstronomyCast    In this episode, we'd like to thank: Andrew Poelstra, BogieNet, Brian Cagle, Burry Gowen, David, David Rossetter, David Truog, Ed, Gerhard Schwarzer, Jason Kwong, Jeanette Wink, Michael Purcell, Olger, Sergio Sancevero, Sergey Manouilov, Siggi Kemmler, Stephen Veit

Hosted by: Fraser Cain and Dr. Pamela L. Gay Streamed live on Oct 6, 2025. You can only describe a black hole by its mass and its spin. And maybe it’s charge. But allow us to propose a new criteria: the personal experience. Some black holes have seen things… Experienced the laws of physics at their most extreme. And today we’ll tell their stories. The more of the sky we observe, the more bizarre situations we find black holes in. Let's explore!   This show is supported through people like you on Patreon.com/AstronomyCast  In this episode, we'd like to thank: Andrew Poelstra, BogieNet, Brian Cagle, Burry Gowen, David, David Rossetter, David Truog, Ed, Gerhard Schwarzer, Jason Kwong, Jeanette Wink, Michael Purcell, Olger, Sergio Sancevero, Sergey Manouilov, Siggi Kemmler, Stephen Veit

End-of-Life Planning for Your Spacecraft! Streamed live October 1, 2025. Your spacecraft has reached the end of its mission. You’ve done everything you can to keep it operational, but now it’s time to say goodbye. How do space agencies deal with spacecraft to shut them down gracefully, protect future missions and life on other worlds. So, the time has come to see your mission across the Rainbow Bridge. How exactly do you say goodbye? Let's discuss.