Ep. 771: Comet Tails
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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...
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Ep. 770: The Ethics of Mars Exploration
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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...
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Ep. 769: Little Red Dots
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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...
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Ep. 768: Comets' Unpredictability
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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....
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Ep. 767: Black Holes in Extreme Circumstances
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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,...
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Ep. 766: How Spacecraft End
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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.
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Ep. 765: Rockets vs The Environment
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Streamed live on Sep 22, 2025. We don’t launch a lot of rockets every year, so their impact on the environment is minimal compared to other forms of transportation. But that number is steadily increasing with rates that we’ll have to take seriously. What’s the current and future impact of rockets on the environment Rocket facilities are often surrounded by wildlife preserves and they always fly through our atmosphere. Let's take a look at how launches do and don't impact the environment around them from the surface of Earth, to the farthest orbits (and landings).
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Ep. 764: Cleared For Launch!
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Streamed live September 17, 2025. This week, we look at the process behind rockets getting licensed to launch, and everyone around the pad getting notified to stay away as T-0 approaches. (Can you say "errant boat"?) We have a saying around here: “One does not simply book a return trip from a rocket launch.” That’s because they are an intensely complex chain of events that need to go right before it’s wise to let that rocket leave the launchpad.
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Ep. 763: Interstellar Comets
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Streamed live Sep 8, 2025. Welcome to the first episode of our 19th season! This week we look at objects coming from other solar systems that come passing on by our Sun. During the summer hiatus the 3rd interstellar object was discovered: Comet 3I/ATLAS! So now we have 3 different interstellar interlopers to compare & contrast. What are we starting to learn about other star systems from this small sample size and how will our detection get even better? [Editor’s note: HiRISE’s telescope is 1/2 meter.]
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Ep. 762: Science in Crisis - NASA’s New Budget
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Streamed live on Jun 30, 2025. Hosted by: Fraser Cain and Dr. Pamela L. Gay Normally we try to end the season on a high note. But there’s unfolding news that we just HAVE to cover before we leave you for the summer. NASA’s new budget is here, and it’s 25% smaller. We’ll cover what the changes are and try to understand the implications. It's a bad decade to be a researcher. We're going to look at why, and what US cuts will mean for the world. [Editor's note] There was an audio problem with Pamela's mic. So there were a few long pauses where she wasn't heard. I put in a coo-coo...
info_outlineStreamed live on Mar 24, 2025.
Hosted by: Fraser Cain and Dr. Pamela L. Gay
The Hubble Tension is a vexing problem, with astronomers measuring the expansion of the Universe at different points in its history and getting different results. Errors have mostly been ruled out, which leaves the potential for new physics. Has the strength of dark energy been changing over time? We thought Dark Energy was constant with time, but new results from DESI say maybe not, and honestly, if it wasn't constant the Hubble Tension would be a whole lot easier to solve.
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