Awesome Astronomy Podcast

Episode 169: Vanishing Stars and Invisible Galaxies

Date: March 1, 2026
Hosts: Paul & Dr. Jeni

Episode Overview

This episode of Awesome Astronomy takes a deep dive into groundbreaking discoveries about disappearing stars and nearly invisible galaxies composed almost entirely of dark matter. Paul and Dr. Jeni blend cutting-edge astronomical research with their signature humor, bringing listeners up to speed on everything from rare stellar dimming events and elusive dark galaxies to observational highlights for amateur astronomers.

Major Discussion Points & Insights

Catching Up, Housekeeping, and Upcoming Events

0:00–9:52

• Personal Anecdotes: Jeni recounts her chaotic week featuring an accidental adventure into new forms of ‘bioscience’ while fixing a blocked drain—“There must be organisms living in this thing that no one has discovered, no one's seen before.” (A, 02:42)
• AstroCamp Announcement: Tickets officially on sale! Open invitation for listeners worldwide. “We'd love to break the record for the, like, most distant traveler.” (A, 06:26)
• Email Troubles: The team addresses ongoing technical issues with their email inbox and encourages continued listener contact as they work to resolve it, quipping, “Unless it's a dick dick.” (A, 08:20)
• Upcoming Stargazing Trips: Jeni prepares for another cruise to Norway, hopeful for multiple nights under the northern lights. “If I can have three good nights out... I'd be happy.” (A, 09:15)

NEWS: Stellar Mysteries & Discoveries

9:52–33:12

The Vanishing Star in Monoceros

10:29–19:48

• Headline: Sun-like star ASAS-SN 24fw exhibited a dramatic dimming—40x fainter for ~9 months (Sep 2024).
• Irregularity: Such behavior is unheard of for stable main sequence stars. “Regular main sequence stars don't do that sort of thing. No, they just don't.” (A & B, 11:30–11:44)
• History Repeats: Past records revealed similar events in 1937 and 1981, implying a 44-year periodicity. “If they'd thrown those plates away... wouldn't have known about this. You got to keep it all.” (B, 12:56)
• Spectroscopic Findings: Using multiple observatories, researchers found not a typical dusty thin disk but a thick, gas- and metal-rich circumstellar disk. “Rather than a dusky, dusty, thin disc... this is surprising in a couple of ways...” (B, 14:04)
• Possible Cause: Debris from a major planetary collision long after the star’s formation—“Do you know what, that was in my brain! I wonder if it's gonna be some kind of event.” (A, 15:58)
• Further Theories: A massive planet (several Jupiter masses) may shepherd disk material, leading to periodic obscurations—likened to a “diamond ring” with a clump.
• Memorable Quote: “Shows the universe is very far from static... billions of years later, massive collisions... create these kind of debris fields.” (B, 19:25)

Discovery: (Almost) Invisible "Dark" Galaxies

19:49–33:12

• Context: Discussion on ultra-diffuse galaxies—difficult to detect due to low starlight but identified by clusters of globular clusters (“globs”).
• Perseus Cluster Discovery: Using Hubble, astronomers find a candidate galaxy almost entirely composed of dark matter; only the faintest starlight is visible, with ≥16% of its stellar mass in globs.
• “You can see the four dots for the glob... and then you kind of squint and you're like, maybe there's some starlight.” (A, 26:12)
• Key Technique: Looking for globular cluster overdensities to find galaxies that are otherwise optically invisible.
• Galaxy Evolution: Such “dark galaxies” likely lost their normal matter through tidal stripping in cluster interactions, leaving globs behind; opens the possibility of even fainter (truly starless) galaxies.
• Implications for Dark Matter: These discoveries provide indirect support for dark matter’s existence. “These globs are being tied together by something and you can't see that something. So it has to be dark matter.” (A, 29:24)
• Scientific Context: Ongoing debate—dark matter remains a leading hypothesis, but without direct particle detection, the field remains open. “It's not strong enough to be a theory even, because there's so many competing ideas.” (B, 30:21)
• Resource Recommendation: Astronomy Now magazine’s latest issue features an in-depth dark matter article—praised for new editorial quality and QR code enhancements for sourcing papers.

Artemis 2 and Spaceflight Updates

33:12–36:52

• Quick Mention: NASA’s Artemis II mission rolled back due to a helium pressurization issue; launch likely delayed beyond the targeted April window.
• Predictions: Paul bets autumn 2026 for liftoff; Jeni hopes for June to match upcoming travel.
• Memorable Banter: “I'm gonna make a prediction… end of summer into autumn...” (B, 34:38)

ALMA’s Largest Ever Image and Multispectral Galactic Core Research

36:42–37:34

• Science News: ALMA captures its largest image ever, spanning three full moons and revealing the star-forming heart of the Milky Way’s central molecular zone; more findings expected as the data is analyzed.

Observing Guide: What’s Up in the March Sky?

37:34–59:01

Planets & Occultations

• Venus returns to the evening sky, low on the western horizon after sunset, bright and unmistakable. “...the brightest thing in the sky bar the moon and sun is going to be starting rumors of UFOs again...” (B, 38:33)
• Jupiter: Still shining in Gemini, past opposition but full of dynamic moon events (shadow transits, Great Red Spot appearances).
• Special Event: Regulus (brightest star in Leo) occulted by the moon on March 29th, a rare sight. “It's a pretty surprisingly rare event that the moon passes in front of a bright star.” (B, 40:14)

Comet Watch

• Comet C/2024 E1 (Weirzchos?): Approaching northern skies, potentially visible in small telescopes at mag ~10 at month’s end.

Messier Marathon (March Tradition)

• Challenge: Attempt to observe all 110 Messier objects in a single dusk-to-dawn session. Preparation and horizon planning are key. “It is one of the greatest observing challenges that any backyard astronomer can ever attempt...” (A, 45:18)
• Strategy Tips: Go by right ascension, stay awake through “the three hour gap” after Virgo, and don’t nap!
• Book Recommendation: 110 Things to See With a Telescope (John Reed & Sey Vaughan).

Paul’s Deep Sky Tour: Targets in Gemini

• Open Clusters:
  • M35: “One of the finest open clusters in the sky... If you can have one Messier, this is a good one.” (B, 49:17)
  • NGC 2158: More distant companion to M35.
• Planetary Nebulae:
  • NGC 2392 (Clown Face Nebula): High surface brightness, striking face-like appearance.
  • IC 443 (Jellyfish Nebula): Supernova remnant, delicate arcs of gas—best viewed with OIII/UHC filters.
• Double & Notable Stars:
  • Castor: Splits into blue-white pairs; actually a sextuple system.
  • Pollux: Bright orange giant, potential exoplanet host.

Lunar Features (Day 10–12 Update)

• Sinus Iridium (Bay of Rainbows): Semicircular flooded crater.

• Copernicus Crater: Fully illuminated.

• Aristarchus Plateau & Crater: Highly reflective, standout white area.

• Gassendi: Remarkable fractured floor.

• Oceanus Procellarum: Largest lunar mare, “ocean-sized” basalt plain.

• Grimaldi: Dark-floored crater, striking near the lunar limb.

• Shikard: Massive, tie-dye patterned floor.

• Quote: “The Moon is so cool. It's always overlooked... But go back to [it,] it's such a cool object.” (B, 57:55)

Notable Quotes & Moments

On the Vanishing Star:

“Regular main sequence stars don't do that sort of thing. No, they just don't.”
—Jeni, 11:44

On Data Archiving:

“If they'd thrown those plates away... wouldn't have known about this. You got to keep it all.”
—Paul, 12:56

On Dark Matter Galaxies:

“These globs are being tied together by something and you can't see that something. So it has to be dark matter.”
—Jeni, 29:24

Philosophy of Science:

“It's not science to say, yes, it absolutely, definitely exists because we haven't found like a particle.”
—Paul, 29:58

On the Messier Marathon:

“If you can get halfway, then you get a gold star, to be honest, because... you do a bunch at the beginning and then you... got this three hour gap in the middle while you're waiting for stuff to rise. Do not do what I did, which is go in and have a little nap...”
—Jeni, 46:56

Timestamps: Key Segments

• Vanishing Star in Monoceros: 10:29–19:48
• Discovery of Dark Galaxy in Perseus Cluster: 19:49–33:12
• Artemis II Update: 33:12–36:52
• ALMA’s Large Image Release: 36:42–37:34
• What’s Up in March’s Sky: 37:34–59:01

Closing

Paul and Jeni wrap up the show with lunar observing tips and a reminder:

“If you have any comments... send them over to us at the show awesome astronomy.com... So until next time, it's goodbye from Cydonia Base.” (A, 59:01)

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