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Walkabout the Galaxy

Walkabout the Galaxy

Joshua Colwell, Adrienne Dove, and James Cooney · Joshua Colwell

364 episodesEN

Show overview

Walkabout the Galaxy has been publishing since 2015, and across the 11 years since has built a catalogue of 364 episodes. That works out to roughly 270 hours of audio in total. Releases follow a fortnightly cadence, with the show now in its 7th season.

Episodes typically run thirty-five to sixty minutes — most land between 42 min and 49 min — and the run-time is fairly consistent across the catalogue. It is catalogued as a EN-language Science show.

The show is actively publishing — the most recent episode landed yesterday, with 8 episodes already out so far this year. The busiest year was 2021, with 45 episodes published. Published by Joshua Colwell.

Episodes
364
Running
2015–2026 · 11y
Median length
46 min
Cadence
Fortnightly

From the publisher

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

Latest Episodes

View all 364 episodes

Little Plutino Has An Atmosphere and Making Sense of Saturn

May 13, 202647 min

Superkilonova and Artemis II Recap

Apr 28, 202645 min

Ep 422A Whisper of a Hint of Primordial Black Holes plus Earth BLOBs

Gravitational Wave observatory LIGO has seen a signature that looks like the merger of primordial (pre-stellar, big bang (not big band!) era) black holes. If confirmed with future observations, this would tell us a lot about the early universe and potentially shed light on dark matter. Finally! Plus, closer to home, the BLOBs in the Earth's mantle help us untangle the complicated past of our magnetic field.

Mar 18, 202640 min

Ep 419Supermassive Black Holes Supersoaking Other Galaxies

Supermassive black holes can be terrible neighbors. New research shows that their powerful jets of charged particles can shut down star formation in neighboring galaxies within the galaxy cluster, which is just plain rude. Closer to home, our own Down Quark Audrey Martin is part of a study shedding new light (with the James Webb Space Telescope) on the mysterious L type asteroids, that formed at very high temperatures early in our solar system's history.

Feb 25, 202638 min

Ep 418Snowball Earth was Cold and Scary and the Milky Way Magnetic Field is a Mess

The Earth spent some crazy amounts of time (tens of millions of years) completely frozen over. And not, in the grand scheme of things, all that long ago. New research shows the ocean was salty and super-cold. How did life survive? New techniques using radio observations reveal a complicated and twisty galactic magnetic field. Join us for an icy, winter olympics themed episode to find out all this and more.

Feb 18, 202646 min

Ep 417Planetary Nebulae and Active Asteroids Get a Closer Look

There's always been a fuzzy line between asteroids and comets, and new observations of asteroids in the vicinity of Jupiter provide a hint to the origin of the mysterious active asteroids that look like asteroids but act like comets. Elsewhere in the galaxy, the famous ring nebula gets a new spectral image that shows the presence of band of iron. Could it be the remnants of a planet like Earth or Mercury that was vaporized when the nebular formed? Tune in for our take on this, space news, trivia and much more.

Feb 5, 202641 min

Ep 416A Dark Universe Unveiled

Scientists head to the volcanic fields of Iceland to test instruments for the VERITAS mission to Venus, Artemis II is ready for its historic flight to the Moon, and the Dark Energy Survey reveals the distribution of dark matter on an astounding scale. For mind-blowing astro-stuff, space news, and trivia, join the astroquarks on Walkabout the Galaxy.

Jan 29, 202644 min

Ep 415Crazy Spinners in the Asteroid Belt and S8 Tension

The amazing discoveries from the Vera C. Rubin Observatory have already started, and the astroquarks take a look at some close to home. Asteroids bigger than a city block spinning in fewer than 5 minutes are just the beginning, and will change our understanding of the collisional evolution of the asteroid belt. The astroquarks muse on the biggest questions in astronomy today, and one of those, the so-called "S8 Tension" has a possible solution with the help of dark matter and neutrinos. Join us for all that, space news, trivia, and more.

Jan 14, 202646 min

Ep 414Cosmic Rays from Everywhere and Stringy Ancient Galaxies

The Parker Solar Probe flies through the Sun's corona, MAVEN has gone silent, and new data shed light on the origins of cosmic rays. JWST's observations of ancient galaxies reveal odd shapes that may be connected to dark matter. Join us for a year-end look at the latest discoveries and space news and much more.

Dec 17, 202542 min

Ep 413Interstellar Star Scars and Poop on Mars

We explore the dining and drinking choices for astronauts, complex chemicals discovered in asteroid samples, and untangling the web of scars in the local interstellar cloud to reveal past encounters of the Sun with some hot stellar neighbors. If you wish you had more hot stellar neighbors, you should definitely check out this episode of Walkabout the Galaxy.

Dec 10, 202538 min

Ep 412Gravothermalizing and Baby Black Holes

There's a new funky proposal for small black holes in the early universe, and another potential dark matter candidate. Learn about cannibal stars and much more, together with double trivia and space news with your friendly neighborhood astroquarks.

Dec 4, 202546 min

Ep 411An Ancient Moon of Mars?

The story behind this investigation is almost more cool than the discovery itself. Microlayers of sediments in Mars' Gale Crater, observed by NASA's Curiosity rover, are indicative of tidal sloshing of water in the lake that once filled the crater. Problem is, the age of the rocks and the magnitude of the tides would require a different moon than the ones currently there. Cool! Join us to hear about that, interstellar comet 3I/Atlas, and much more.

Nov 26, 202543 min

Ep 410Why Is There A Universe At All?

Things would be a lot simpler and a lot less interesting if charge parity existed in the universe, but there would be no one to appreciate that simplicity because we would not exist! New results from the Large Hadron Collider provide a hint at explaining why there is matter in the universe and it was not all eliminated in a dramatic annihilation of matter-antimatter collisions. So, that's a relief! And we have space news, meta-trivia, solar system news and more. Join us, won't you?

Nov 20, 202536 min

Ep 409The Amazing and Crazy Story of Gemini and Jumbo Black Holes

The astroquarks are joined by Jeffrey Kluger, editor at large at Time Magazine and author of 13 books including Apollo 13 and the new book on the Gemini program. Tune in to hear about some of the outlandish ideas that were explored on the way to the Moon. Plus, top quark gives us a look at a new class of black holes that we've decided are "Jumbo Black Holes". All that plus twin trivia, a hot take, and more.

Nov 5, 202544 min

Ep 408Rings Around a Comet, Betelbuddy, and Odd Jupiter Moons

These rings aren't around Uranus, they're somewhere even more odd. We discuss the mysterious and changing ring system around the Centaur object Chiron, new clues about the origin of the solar system from the irregular moons of Jupiter, and the puzzling stellar companion to Betelgeuse. Plus, top quark Jim Cooney stumps us with trivia.

Oct 29, 202549 min

Ep 407Adaptive LIGO and a New Look at an Old Crater

Adaptive optics techniques get applied to the mirrors in the LIGO gravitational wave observatory, promising a five-fold or greater improvement in sensitivity to gravitational waves from colliding black holes across the universe. And right here in our backyard, a suspicious sub-surface crater-like feature gets a new look that appears to confirm its extraterrestrial origin. Join us for space news, trivia, and more.

Oct 1, 202539 min

Ep 406Einstein Cross Reveals Dark Matter and a Life-y Mars Rock

We take a look the Cheyava Falls rock on Mars, or rather the Perseverance rover took a look at it, and we discuss what it saw which were some intriguing mineral formations that could have a biological origin. And gravitational lensing has enabled astronomers to map the distribution of dark matter in a small cluster of galaxies, providing a new tool to understand the distribution of this mysterious stuff. Join us for these stories, space news, space trivia, and a fake sponsor!

Sep 24, 202542 min

Ep 405Exo-Pluto Debris in Our Solar System and Axions Galore

An interstellar interloper may have been a chip off the old block, where the old block was a Pluto-like planet around another star, and the chip is solid air (nitrogen that is)! And we revisit the potential role of axions in the great dark matter chase and a new way that JWST may help us answer it. Join us for all that, exoplanets, science fiction trivia and more.

Sep 10, 202546 min

Ep 404Europa Clipper Report from Mars and ATLAS 3I Update from DragonCon 2025

That's no error, this is episode 404, recorded in front of a live audience at DragonCon 2025 with special guest Trina Ray, Deputy Science Manager for the Europa Clipper mission. We get an update from the cool RADAR test the spacecraft conducted at Mars, new information on the history and composition of Interstellar Comet ATLAS 3/I and a super-duper-massive black hole. Join us for all this, 404 trivia, and more.

Sep 3, 202537 min

Ep 403Trappist-1, ESCAPADE, and Axions

There is so much going on in the universe it's hard to keep track. That's why we have not one but two top astroquarks on this episode to cover the latest discoveries and news from the solar system to the deepest recesses of space. A search for a habitable atmosphere comes up empty, while a mission to study the loss of Mars' atmosphere nears launch. And a clever new technique may be able to detect the hypothesized axion, a candidate particle for dark matter. Check it out, with space news, trivia, and more.

Aug 20, 202541 min
Joshua Colwell