Walkabout the Galaxy

An irreverent and informative tour of the latest, greatest, and most interesting discoveries in astronomy.

The Low Down on Big G and the Young Moon of Dinkinesh 05/08/2024

The Low Down on Big G and the Young Moon of Dinkinesh NASA's Lucy mission discovered a surprising moon of the small asteroid Dinkinesh on its way to the orbit of Jupiter. New studies of that moon, a contact binary, suggest it may have a surprisingly young age. Meanwhile, cosmologists continue to wrestle with various seemingly contradictory measurements. One model suggests a modification to that old Physics 1 standby, the gravitational constant (or is it?) G. Join us for all the astronomical news near and far, including space news updates and trivia. /episode/index/show/walkaboutthegalaxy/id/31188697

Dark Matter Wins Again 05/01/2024

Dark Matter Wins Again A clever test of dark matter and an alternative theory of gravity to explain the motions of stars around galaxies results in another check in the win column for dark matter. Simulations with the modified model of gravity failed to explain the motions in the inner regions of galaxies. Meanwhile the search for a hypothesized large object in the distant reaches of our solar system has so far come up empty suggesting that it may be larger and more distant than previously thought. Join us for all the intriguing and exciting space news in the universe! /episode/index/show/walkaboutthegalaxy/id/31076463

Surprises from Bennu and the Milky Way 04/03/2024

Surprises from Bennu and the Milky Way Analysis of the samples returned from the asteroid Bennu have revealed surprising assemblages of minerals that put new constraints on the origin of the solar system. And once Top Quark Jim Cooney stops giggling, he tells us about the discovery of an itsy-bitsy galaxy, if you can call it that, orbiting the Milky way. It has only dozens of stars, plus, probably some dark matter. Join us for these surprising discoveries, space news updates, variable star trivia, and a generally good time. /episode/index/show/walkaboutthegalaxy/id/30651513

The Dark Ages of the Universe 03/27/2024

The Dark Ages of the Universe We peer back in time both to the murky history of our own solar system and to the dark ages of the universe. The JWST has confirmed that dwarf galaxies were the first to illuminate the universe, putting an end to the dark ages that followed the cooling after the big bang. In our own corner of the universe, new research highlights how nearby stars can lead to dramatic changes in our planet’s climate by affecting the Earth’s orbit. Join us for all this, nerd news, space news, and eclipse trivia. /episode/index/show/walkaboutthegalaxy/id/30563378

A Nova Visible this Year? 03/20/2024

A Nova Visible this Year? One of only a handful of recurrent novas, white dwarf stars that undergo a periodic explosive brightening as they accrete material from a neighboring star, is showing signs that it may be ready to blow sometime in 2024! Visible in the northern hemisphere, T CrB may become visible to the naked eye for a few days this year, repeating a cycle that occurs roughly every 80 years. Closer to home, new analysis of structures and composition on Mars' Tharsis bulge reveal what may be a previously unknown and now-extinct volcano. Join us for explanations, space news, spaceflight trivia and more. /episode/index/show/walkaboutthegalaxy/id/30461753

Psyche Revisited and Two Giant Black Holes 03/06/2024

Psyche Revisited and Two Giant Black Holes The presumed metallic asteroid Psyche gets a new look before the spacecraft of the same name gets there in 2029, and it reveals different spectral characteristics than were observed in previous studies. We discuss the mystery of metallic asteroids and what we might see at Psyche. Top quark educates us about the largest binary black hole system, with two supermassive black holes orbiting each other from an ancient galactic collision. Join us for all this, space news, and tiny rocket trivia. /episode/index/show/walkaboutthegalaxy/id/30255153

The Tiniest Ocean World and the Brightest Quasar 02/28/2024

The Tiniest Ocean World and the Brightest Quasar Saturn's so-called Death Star moon Mimas may harbor a global subsurface ocean based on analysis of Cassini data of the tiny moon's orbit and rotation. And in the distant universe, what was previously thought to be a run-of-the-mill star in our own galaxy turns out to be a quasar thousands of times brighter than our entire galaxy itself. Join us on our 350th episode for breakthroughs in astronomy near and far, space news, sci-fi trivia, and more. /episode/index/show/walkaboutthegalaxy/id/30110638

Space Oddities in the Solar System 02/21/2024

Space Oddities in the Solar System Water molecules have been observed on the surface of an asteroid for the first time, and new studies help explain some of the odd behavior of planetary ring systems, including why they even exist around small objects in the outer solar system. Join us for a clear and fun explanation, the latest from Mars, upcoming missions, space trivia and more. /episode/index/show/walkaboutthegalaxy/id/30050253

When Will We Walk on Mars? 02/07/2024

When Will We Walk on Mars? In this special episode recorded live at MegaCon Orlando 2024, we are joined by NPR space reporter Brendan Byrne to take a close look at where we are in the mission to get people to the red planet. We take a look at the next steps in the Artemis program, and the history and future of robotic exploration of Mars. Find out when we will walk on Mars, where the best places to walk are, and we answer a listener question on the three body problem. /episode/index/show/walkaboutthegalaxy/id/29841088

Large Cosmological Structures and JWST Spies a Binary TNO 01/31/2024

Large Cosmological Structures and JWST Spies a Binary TNO There's another claim for a violation of the cosmological principle - that all parts of the universe are basically the same on large scales - but Top quark Jim Cooney explains all is not lost for the standard model of the universe, and more observations are needed. The JWST is providing amazing observations near and far, and has now separately measured the composition of two orbiting trans-Neptunian objects (TNOs), confirming that they are made of the same stuff. We explain the implications of this together with the latest space news, a time loop stumper, and walkabout trivia. /episode/index/show/walkaboutthegalaxy/id/29681353

Trojan Mysteries and Titan Snowbergs 01/24/2024

Trojan Mysteries and Titan Snowbergs Strange disappearing islands in the hydrocarbon lakes of Saturn's giant moon Titan may be fluffy icebergs of hydrocarbon snow. If you're on Titan, definitely don't eat the snow, yellow or not. As the Lucy mission heads towards the Trojan asteroids, questions remain about how this strange population of objects formed. We catch up with all the space news, a time travel stumper, and lunar exploration trivia. /episode/index/show/walkaboutthegalaxy/id/29582073

Agents of Chaos and Iron Snow 01/10/2024

Agents of Chaos and Iron Snow What role has Jupiter played in the existence of our warm and cosy home planet? Has it been bravely using its gravity to keep the inner solar system calm, or did we luck out and escape getting hurtled out of the solar system or dashed to bits in a giant collision? We’ll discuss new research that explores exoplanetary systems with multiple large planets and whether habitable planets can co-exist with them. And within our own planet we learn about iron snow at the core mantle boundary and its effects on our magnetic field. Join us for all this cool stuff, plus space news and trivia. /episode/index/show/walkaboutthegalaxy/id/29360723

Globular Clusters and Life in Enceladus 12/21/2023

Globular Clusters and Life in Enceladus New analysis of Cassini data suggests more complex hydrocarbons are part of Enceladus's global sub-surface ocean. We discuss the prospects for life on this tiny moon. The JWST continues to deliver scientific bonanzas, now providing direct observations of globular clusters in very distant galaxies, helping us understand these enigmatic and ancient structures. Join us to explore these mysteries and for space news and special down quark holiday-themed space trivia. /episode/index/show/walkaboutthegalaxy/id/29185733

Pluto Cryovolcano and a Cosmological Supervoid 12/13/2023

Pluto Cryovolcano and a Cosmological Supervoid At Pluto’s frigid temperatures, even what we breathe is frozen. This can give rise to unusual cryovolcanism, and new research suggests a super cryovolcano tens of kilometers across on the ninth planet (yes, we went there). Speaking of super things, we also review the argument that we are located in a cosmological supervoid and whether than can explain some of the mysteries surround the Hubble constant. Join us for all that, space news, trivia and more. /episode/index/show/walkaboutthegalaxy/id/29043143

Mysterious Cosmic Ray and Martian Airglow 12/06/2023

Mysterious Cosmic Ray and Martian Airglow The second most energetic cosmic ray (really a particle) ever observed smashed into the Earth a couple of years ago, raising more questions about the origins of these incredibly energetic particles. Solar wind particles meanwhile smash into the planets, and now a green glow from Mars' atmosphere has been observed by one of the many spacecraft exploring the red planet. We also discuss a surprising exoplanet discovery, moon trivia, space news and more. /episode/index/show/walkaboutthegalaxy/id/28944468

Ethical Dilemmas in Space Exploration 11/22/2023

Ethical Dilemmas in Space Exploration The astroquarks are joined by Dr. Erika Nesvold, astrophysicist and author of “Off Earth: Ethical Questions and Quandaries for Living in Outer Space” to explore some of the surprising problems people need to think about when going to space. We’re busy littering already, but that’s just the tip of the asteroid. Join us for a discussion of some of the trickier issues of space exploration, space news, and gravitational wave trivia. The only place you can find that lineup is on Walkabout the Galaxy. /episode/index/show/walkaboutthegalaxy/id/28721773

The Origin of Supermassive Black Holes 11/15/2023

The Origin of Supermassive Black Holes JWST data confirm early formation of supermassive black holes, less than 500 million years after the big bang. This early formation suggests these monsters start off very large and form with the initial formation of the galaxy. We also take a closer look at the exciting results from the Lucy spacecraft's flyby of the asteroid Dinkinesh and its surprising moon. Join us for all this, space news, and top quark trivia. /episode/index/show/walkaboutthegalaxy/id/28652453

Dinky and the S8 Tension 11/08/2023

Dinky and the S8 Tension The Lucy spacecraft had its first asteroid encounter, revealing Dinkinesh to be a binary asteroid. In cosmology, a new simulation with a terrible acronym leaves the "S8 Tension" intact. Models of the expansion of the universe starting with our observations of the cosmic microwave background are in disagreement (tension) with observations of the actual distribution of superclusters of galaxies. Are there errors that haven't been uncovered, or perhaps new physics? Join us for our thoughts on these and other news in space, and some literally mind-blowing trivia. /episode/index/show/walkaboutthegalaxy/id/28543331

The Surprising Interiors of Mars and Venus 11/01/2023

The Surprising Interiors of Mars and Venus New research suggests that Venus, Earth’s twin gone bad, may have started off with tectonic plate activity, like Earth. This will help us understand the evolution of Earth-like planets and why they become hothouses like Venus. Our other planetary next-door neighbor, Mars, may have a deep molten magma ocean, revealed thanks to a fortuitous meteoroid impact on the planet whose shaking was recorded by Mars Insight. Join us for these insights, space news, and more. /episode/index/show/walkaboutthegalaxy/id/28484951

Detecting ETs and Intergalactic Baryons 10/25/2023

Detecting ETs and Intergalactic Baryons Fast Radio Bursts are back, this time providing a crucial measurement of the amount of normal matter in the universe. Top quark Jim Cooney explains how the interaction of light from very distant gamma ray bursts reveals the otherwise invisible matter sprinkled in the intergalactic void. Somewhat closer to home, JWST is providing tantalizing glimpses of the composition of extrasolar planets, a technique that may one day discover alien life. Join us for these and other discoveries, space news, and podcast trivia. /episode/index/show/walkaboutthegalaxy/id/28406930

Neutron Star Quakes and the Streaming Instability 10/18/2023

Neutron Star Quakes and the Streaming Instability Images of the distant Kuiper Belt Object Arrokoth add more weight to the pebble accretion model of planetesimal formation via the streaming instability. If that sounds strange, then you'll really love the story about comparing Fast Radio Burst statistics to earthquakes. This study suggests that these energetic bursts of radiation may be produced by quakes on neutron stars. Join us for these stories, space news, and space history trivia. /episode/index/show/walkaboutthegalaxy/id/28341536

Pangaea Ultima, Antimatter Gravity, and the Evection Resonance 10/04/2023

Pangaea Ultima, Antimatter Gravity, and the Evection Resonance The next supercontinent could spell bad news for mammals. The equivalence principle passes another test, with antimatter atoms falling just like normal matter atoms, and Josh gets excited about the evection resonance and the role it may have played in the formation of Saturn’s rings. Plus, we have top quark trivia and a nerd news rant. Join us! /episode/index/show/walkaboutthegalaxy/id/28190594

Short Take: Asteroid Sample and Dark Matter Hopes 09/27/2023

Short Take: Asteroid Sample and Dark Matter Hopes Strange and Top discuss the return of the sample from the asteroid Bennu and an intriguing measurement from a dark matter detector in Italy in this, our first Short Take episode. Sadly, the measurement has not been reproduced. Yet. A new detector in Australia will try to confirm the Italian result. /episode/index/show/walkaboutthegalaxy/id/28157450

Trouble in the Universe: El Gordo and Dinky 09/20/2023

Trouble in the Universe: El Gordo and Dinky There's more tension in the standard model of the history of the universe. Giant superclusters of galaxies formed early than we thought they could. These collosal structures trace their origins to quantum fluctuations in the early universe. Find out what it all means, plus chthonian planets, asteroid encounters and more on Walkabout the Galaxy. /episode/index/show/walkaboutthegalaxy/id/28056177

Ho'oleilana and Weird Spots on Mercury 09/13/2023

Ho'oleilana and Weird Spots on Mercury This episode is about hollows in space on very different scales and for very different reasons. Ho'oleilana is the largest observed structure in the universe, a bubble of sorts defined by great sheets of galactic superclusters whose size is a reflection of acoustic oscillations in the very early universe. Closer to home, we take a look at mysterious hollows on Mercury indicative of some sort of recent geologic activity. Join us to learn about these strange features, space news, radiation trivia and that unmistakable astroquark spark. /episode/index/show/walkaboutthegalaxy/id/27993807

Water in the Solar System - Dragoncon 2023 09/07/2023

Water in the Solar System - Dragoncon 2023 The astroquarks report from Dragoncon 2023 on the surprisingly diverse distribution of water in the solar system, where it came from, and the prospects for life on other worlds. We are joined by planetary geologist R. Scott Harris for this special episode with a live audience. This episode of Walkabout the Galaxy also features obscure sci-fi trivia, space news, and your hosts in silly costumes. /episode/index/show/walkaboutthegalaxy/id/27973107

Diamonds, Granite, and Hubble Tension 08/30/2023

Diamonds, Granite, and Hubble Tension When we think of all the wonderfully unique things about the Earth as a planet (liquid water on the surface, life, plate tectonics), the existence of lovely granite kitchen countertops doesn’t usually make the list. But it turns out granite is uncommon elsewhere in the solar system. But there’s a big hot blob of it underneath the lunar surface. We’ll explain that, the origin of diamonds on Earth, and take a closer look at the puzzling discrepancy of values of the Hubble constant thanks to JWST. Join us for all that and the first ever Charm Quark trivia. /episode/index/show/walkaboutthegalaxy/id/27873609

The Sun Bounces Gamma Rays and a Muon Surprise 08/16/2023

The Sun Bounces Gamma Rays and a Muon Surprise The Sun is showering us with far more gamma rays than anticipated according to new measurements from a Cerenkov radiation detector in Mexico. The way those gamma rays are produced is very cool. Also cool: data continue to suggest a significant problem with the so-called standard model of particle physics. Muons are misbehaving, and it may suggest a fifth, previously undescribed and unknown, force of nature. Check out all that cool stuff, silly sponsors and trivia, and space news on this episode of Walkabout the Galaxy. /episode/index/show/walkaboutthegalaxy/id/27771540

Rogue Planets Galore and the Age of the Universe 08/09/2023

Rogue Planets Galore and the Age of the Universe We take a look at two extraordinary astronomical news items in this episode. A deep dive into an astronomical survey has discovered an Earth-sized rogue planet and a Neptune-sized rogue planet. Extrapolating from those discoveries, there may be trillions of Earth-sized rogue planets roaming the galaxy. That's more than the number of stars in the Milky Way! We also explore the question of early galaxies and a model that suggests the universe is older than the standard model. As a bonus, we have some wacky Top quark trivia, space news, and more. /episode/index/show/walkaboutthegalaxy/id/27702507

Dark Stars and Water in Hot Places 08/02/2023

Dark Stars and Water in Hot Places The JWST has spotted water vapor in the hot inner region of a protoplanetary disk, the same region where rocky planets like are own are expected to form. This suggests water can be incorporated into terrestrial planets during formation, without relying on comet impacts. Much, much further away, a new interpretation of JWST results is consistent with dark stars. They are actually quite bright, but are powered by the annihilation of dark matter rather than by nuclear fusion. Catch up on these discoveries, planetary trivia, and much more with your friendly neighborhood astroquarks. /episode/index/show/walkaboutthegalaxy/id/27623475

Walkabout the Galaxy

TOPICS