Astronomy Cast

Astronomy Cast

Take a fact-based journey through the cosmos. Tune in to hear weekly discussions on astronomical topics ranging from planets to cosmology. Hosted by Fraser Cain (Universe Today) and Dr. Pamela L. Gay (Planetary Science Institute), this show brings the questions of an avid astronomy lover direct to an astronomer. Together Fraser and Pamela explore what is known and being discovered about the universe around us. Astronomy Cast is supported thru patreon.com/AstronomyCast.

Episodes

May 4, 2026 40 mins
Astronomy Cast Ep. 792: Star Wars Science By Fraser Cain & Dr. Pamela Gay Streamed live April 29, 2026. May the fourth be with you! Isn't that what people say on the international holiday known as Star Wars Day? Today we're gonna talk about the science in everyone's favorite sci-fi fantasy stories. Which of it is real, and which is essentially magic? Let's find out! Let's look at the science of a galaxy long ago and far away. (Did ...
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Astronomy Cast Ep. 791: Chang'e Sample Return By Fraser Cain & Dr. Pamela Gay Streamed live on Apr 20, 2026. Last week we talked about samples from other worlds delivered to Earth by meteorites. But sometimes you've gotta do the job yourself. Visit the far off place and bring the samples home. And today we're gonna talk about China's Chang'e sample return program. How they've delivered rocks from different parts of the Moon, and ho...
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April 20, 2026 33 mins
Astronomy Cast Ep. 790: Meteorites From Other Worlds By Fraser Cain & Dr. Pamela Gay Streamed live April 17, 2026. Even though humanity has returned samples from a fraction of the worlds in the solar system, the cosmos has delivered many more without us having to lift a finger. Meteorites. We have meteorites from the Moon, Vesta and even Mars! What have we learned about these rocks from other worlds? Space missions to other worlds ...
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Astronomy Cast Ep. 789: What Happens When a Planet's Star Dies By Fraser Cain & Dr. Pamela Gay Streamed live on Mar 30, 2026. A star like the Sun only lasts about 10 billion years and it becomes a red giant and finally a white dwarf. This is catastrophic for some of the planets, consumed by the expanding red giant star. But most survive. What happens next in the long, slow cooling to the background temperature of the Universe? This...
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March 30, 2026 32 mins
Astronomy Cast Ep. 788: Life's Molecules Form in Space By Fraser Cain & Dr. Pamela Gay Streamed live on Mar 23, 2026. The theory of evolution how life takes on its wildly different forms. But how did life get started in the first place? It appears the Universe has been making life's molecules in space for billions of years, setting up the conditions for life… everywhere? One of humanity's fundamental questions is "where does life c...
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Astronomy Cast Ep. 787: Evolved Stars (They're not dead yet!) By Fraser Cain & Dr. Pamela Gay Streamed live on Mar 16, 2026. Main sequence stars spend most of their time being… normal. Fusing hydrogen into helium in their cores. Producing radiation. But as their stockpiles of hydrogen run out they switch to other fuels, starting to climb the ladder of the periodic table of elements. And this is when things get weird. As we get more...
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March 16, 2026 34 mins
Astronomy Cast Ep. 786: Wolf-Rayet Stars By Fraser Cain & Dr. Pamela Gay Streamed live on Mar 9, 2026. You think the Sun is a terrifying ball of fire and fury? Wait until you learn about today's topic: Wolf-Rayet stars! These are massive, dying stars hurling their outer layers out into space before detonating as supernovae. Big stars live brief lives, and Wolf-Rayet stars are the punctuation mark we see before things go supernova. ...
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March 9, 2026 29 mins
Astronomy Cast Ep. 785: Magnetars By Fraser Cain & Dr. Pamela Gay Streamed live March 6, 2026. Magnetars are a special type of neutron star with physics that defy comprehension. Magnetic fields so powerful they could strip you apart at an atomic level. But, where do they come from? So many mysteries to uncover about magnetars. Back in December 2004, a gamma rays washed out cameras and zotted satellites as a star on the other side o...
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March 2, 2026 33 mins
Astronomy Cast Ep. 784: Pulsar-Powered Science By Fraser Cain & Dr. Pamela Gay Streamed live on Feb 16, 2026. Pulsars are dead stars and fascinating in their own right, but astronomers can use their predictable rotation for exploring the cosmos in a series of amazing ways. We can detect gravitational waves, navigate the solar system, test general relativity and find exoplanets. Pulsars are the time keepers of the sky, with their pr...
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February 23, 2026 30 mins
Astronomy Cast Ep. 783: Cataclysmic Variable Stars By Fraser Cain & Dr. Pamela Gay Streamed live on Feb 16, 2026. There are many types of variable stars. Today we're gonna talk about cataclysmic variable stars, which are the result of a white dwarf stealing material from a companion star. And this whole process makes supervillain Pamela happy. Gravity is the weakest force, but on the scales of stars, it is capable of great violence...
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Astronomy Cast Ep. 782: Luminous Fast Blue Optical Transients By Fraser Cain & Dr. Pamela Gay Streamed live on Feb 13, 2026. Modern astronomy has found that the Universe can surprise us. Here's one which astronomers have called Luminous Fast Blue Optical Transients. They're kinda like supernovas, they're kind of like gamma ray bursts, but they're not like them. So what are they? In the distant Universe, are blue light flashes, brig...
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February 9, 2026 31 mins
Astronomy Cast Ep. 781: Awakening Black Holes By Fraser Cain & Dr. Pamela Gay Streamed live on Feb 2, 2026. One long standing mystery in astronomy were the quasars. Incomprehensible energy blasting out of a point-like source, billions of light years away. We now know these are actively feeding supermassive black holes, which can turn off and on in a startlingly short period of time. Today: When black holes awaken! Our Universe is f...
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February 2, 2026 32 mins
Astronomy Cast Ep. 780: When Asteroids & Comets Attack! By Fraser Cain & Dr. Pamela Gay Streamed live on Jan 26, 2026. We live in a cosmic shooting gallery. It's not a matter of "if" but "when"! Dinosaurs, blah, blah, blah. You know the drill. But seriously, folks, it's raining rocks & ice out there! How seriously should we take it? What happens when a variety of different objects hit the Earth? Different kinds of objects affect Ea...
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January 19, 2026 30 mins
Astronomy Cast Ep. 779: Milankovitch Cycles By Fraser Cain & Dr. Pamela Gay Streamed live on Jan 12, 2026. Humans live short lives, and from our perspective the seasons are something that come and go with perfect regularity. But astronomers know the terrible truth! And that there are cycles that slowly shift over tens of thousands of years, shifting the cycles and the Earth's climate. Today we'll talk about the Milankovich Cycles! ...
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January 12, 2026 36 mins
Astronomy Cast Ep. 778: Dyson Swarms By Fraser Cain & Dr. Pamela Gay Streamed live on Jan 5, 2026. Freeman Dyson asked a fascinating question. What would it look like if a civilization was using all the energy coming from their star? And what form would this take? This introduced the concept of a Dyson Sphere, or more realistically, a Dyson Swarm surrounding a star. But if you're skeptical about the concept, you're in good company....
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January 5, 2026 35 mins
Astronomy Cast Ep. 777: The Eddington Limit By Fraser Cain & Dr. Pamela Gay Streamed live on Dec 29, 2025. How big can a star get? This is a calculation made by one of the original pioneers of modern astronomy, Sir Arthur Eddington. And it's named after him, the Eddington Limit. Now, astronomers are finding examples of giant black holes early in the Universe, calling into question some of Eddington's assumptions. Let's explore this...
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December 29, 2025 30 mins
Astronomy Cast Ep. 776: The Matter - Antimatter Dichotomy By Fraser Cain & Dr. Pamela Gay Streamed live on Dec 22, 2025. Shortly after the big bang there were almost exactly the same amounts of matter and antimatter in the Universe, but there was just enough of a difference that we live in a matter-dominated Universe. But it didn't have to be that way! Explaining this mystery has been one of the great mysteries in astronomy, and to...
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December 22, 2025 34 mins
Astronomy Cast Ep. 775: The Hydrogen 21-cm Line By Fraser Cain & Dr. Pamela Gay 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 in...
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December 8, 2025 37 mins
Astronomy Cast Ep. 774: How Does Bad Science Happen? By Fraser Cain & Dr. Pamela Gay Streamed live on Nov 8, 2025. 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 publica...
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Astronomy Cast Ep. 773: What Would You Do With $1 Billion For Astronomy? By Fraser Cain & Dr. Pamela 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 as...
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