Here is the cleaned-up transcript:

## Starcast: November 23, 2025

**Jay Shaffer:** Welcome to the Starcast for the week of November 23rd, 2025. I'm your host, Jay Shaffer. And joining me from beautiful Crestone, Colorado, is Mike Lewinski. Howdy, Mike.

**Mike Lewinski:** Good morning, Jay.

**Jay Shaffer:** So, Mike, what's going on in space weather?

**Mike Lewinski:** Well, Jay, the far side of the sun has been quite active this week, with 3 sunspot groups that are producing flares and CMEs. One of those is sunspot 4274, which we've discussed before, and which gave us those magnificent aurora displays on Veterans Day. The sun is going to rotate that sunspot 4274 back into our view after Thanksgiving, so perhaps we'll have another shot at Northern Lights. Until then, the forecast is quite subdued. According to NOAA, we have just a 15% chance of an M-class flare over the next 48 hours. And the probability of a geomagnetic storm of any measure is just 15% at mid-latitudes. At higher latitudes, that bumps up to 20%. And what's happening in the night sky this week, Jay?

**Jay Shaffer:** Well, we got the first quarter moon coming up. The moment of the first quarter moon will fall on 659 Universal Time on November 28th, 2025, that's about 1259 Eastern Standard Time. And as November draws to a close, the celestial dust settles on the annual Leonid meteor shower, which peaked overnight between November 16th and 17th. Although the peak rates of 10 to 15 swift meteors per hour were moderate compared to the historic meteor storms of the past, viewing conditions for the 2025 Leonids were exceptionally favorable. And this was due to the coincidence of the shower's peak with a nearly new moon, which was only about 9% illuminated, providing the dark skies necessary to see the fainter dust particles in the shed of the parent comet 55P Temple-Tuttle. While the Leonids are known for their high speed and potential for bright fireballs, their activity is rapidly dwindling, leaving us stargazers to look forward to the next major event of the winter. And you won't have to wait long for the next major light show, as the Geminid meteor shower, widely considered one of the best and the most reliable of the year, is set to peak in mid-December. The Geminids are expected to reach maximum activity on the night of December 13th and 14th, 2025, with predicted peak rates reaching an impressive 150 meteors per hour under ideal dark sky conditions. Unlike most meteor showers that originate from comets, the Geminids are unique, as their parent object is the asteroid 3200 Phaethon. Or Phaethon, P-H-A-E-T-H-O-N. I'll have to get the pronunciation on that. This year's viewing should be excellent, with the waning crescent moon rising several hours after midnight, allowing for several hours of optimal moon-free viewing in the evening and early night when the shower's radiant point in the constellation Gemini is high in the sky.

And now, for our first story in space news, SpaceX's Starship development program faced a significant setback on November 21st, when the next generation Super Heavy booster, Booster 18, was severely damaged during initial ground testing. The incident adds further uncertainty to the ambitious vehicle's development schedule, which is aiming for crucial milestones like orbital refueling and crewed lunar missions. The Super Heavy booster, which is the first of the upgraded version 3 Starship first stages, was at the company's test site near Starbase, Texas, when an anomaly occurred early in the morning. Independent video footage captured the lower section of the 70-meter-tall booster violently crumpling and partially rupturing around the liquid oxygen tank area. Remarkably, the colossal rocket remained standing, but subsequent images showed extensive structural damage, leading analysts to conclude that Booster 18 is likely a total loss. SpaceX later issued a statement, confirming the incident, quote: "Booster 18 suffered an anomaly during a gas system pressure testing that we were conducting in advance of structural proof testing. No propellant was on the vehicle, the engines were not yet installed. The teams need time to investigate before we are confident of the cause. No one was injured, as we maintain a safe distance for personnel during this type of testing. The site remains clear, and we are working on plans to safely re-enter the site," unquote. Early analysis suggests that the failure may have occurred with a rupture in the high-pressure gas storage tanks, composite overwrap pressure vessels, or COPVs, located in the booster's chime, which then caused the main LOX tank, or liquid oxygen tank, to rupture. The loss of Booster 18, which was intended to support the upcoming Flight 12 and validate the new version 3 architecture, is expected to cause a delay in the testing pipeline as SpaceX pivots to the next vehicle in line, Booster 19.

So, is there another in other space news, Mike?

**Mike Lewinski:** Jay, there's a fascinating new study from researchers at Bielefeld University in Germany, which finds our solar system is moving about 3 times faster than previously believed. This startling result challenges our established standard model of cosmology. Astronomers previously estimated the solar system's speed around the center of the Milky Way at approximately 515,000 miles per hour, or 828,000 kilometers per hour. This new finding, published in a peer-reviewed journal, *Physical Review Letters*, on November 10, 2025, suggests that if our solar system is moving this quickly, it has significant implications for the rotational speed of our galaxy, and by extension, other galaxies across the universe. The lead author, Lucas Bohm, said that the result, quote: "clearly contradicts expectations based on standard cosmology and forces us to reconsider our previous assumptions." To measure this incredible speed, the team looked outside our galaxy at the distribution of distant radio galaxies using instruments like the Low-Frequency Array radio telescope network. Their method relies on detecting a subtle headwind created by the solar system's motion that causes an unequal distribution of radio galaxies to appear in the direction of our travel. Researchers found that this bias was 3.7 times stronger than what the standard model of cosmology predicts, a deviation that is statistically significant. This conflict means scientists must now either, quote, "question fundamental assumptions about the large-scale structure of the universe," which the standard model assumes is relatively uniform, or acknowledge, quote, "the distribution of radial galaxies itself may be less uniform than we have believed."

And this news story leads directly to our discussion this week about cosmology and the Hubble tension. Jay, do you have some thoughts before I get into the details?

**Jay Shaffer:** Yeah, Mike, I find it really fascinating that there's so much activity in cosmological research right now, and I wanted to point out that some of this is directly due to improvements in our instrumentation and also our computing power, whether it's AI or quantum computing, or new satellites or telescopes. So the whole science of cosmology is in a massive state of flux right now, as witnessed by the two studies in the last two weeks that challenge years of previous research. And so, Mike, can you summarize where we stand with cosmology and Hubble tension in particular?

**Mike Lewinski:** Yes. Jay, the simplest explanation of what the universe is doing is that matter is trying to pull everything together, and dark energy is trying to push everything apart. The balance of this pulling and pushing is the rate of cosmic expansion, or the Hubble constant. Now, our early universe was much denser than it is today, so we believe that the attraction of matter must have been stronger, and that as time goes on and matter disperses, the rate of expansion increases. There are a number of ways that we can measure the Hubble constant. The most important of these are Type 1A supernova in galaxies that have Cepheid variable stars, the Cosmic Microwave Background radiation, and a pattern in clustering galaxies known as the Baryon Acoustic Oscillation, or BAO. And we've done previous episodes on all of these except for the BAO. But we'll just say that BAO is sort of the ancient echo of the Big Bang. Now, Supernova observations give us an expansion rate of the universe at between 71 to 75 kilometers per second per megaparsec. Now, the scale of fluctuations in the Cosmic Microwave Background radiation estimate a rate of between 67 to 68 kilometers per second per megaparsec. And the BAO measure estimates a range between 66 to 69 kilometers per second per megaparsec. And this is the Hubble tension. These results should agree, and they don't. And the fate of the universe is quite literally at stake. Will it expand forever and end in the heat death of the universe? Or will it contract back into a big crunch? Now, cosmologists believed that better data should resolve this tension, but it hasn't. Things are actually getting worse. Other methods, such as gravitational lensing and astronomical masers, also contradict each other. The gravitational lens estimate is between 63 to 70 kilometers per second per megaparsec. And the maser estimate is 72 to 77 kilometers per second per megaparsec. And I'll just briefly describe what these other methods are, because I think that they're pretty fascinating. With a gravitational lens, we are looking for a quasar, and one that is... The light of the quasar is... I'm sorry, we're looking for a supernova that has... Let me back up. Yes. That we see through a galaxy, and the galaxy distorts and shifts the light of the supernova. Now, in 2014, we observed a supernova nicknamed Refsdal, which was named after the Norwegian astronomer Sjur Refsdal, who first proposed the idea of time-delayed supernova in 1964. So what happens is, we see a supernova, and because it is being gravitationally lensed by a galaxy, we actually get to observe the supernova multiple times. And so, in 2014, we observed Supernova Refsdal. And the... it was observed that this was located in a gravitationally lensed galaxy. So, astronomers use computer models to predict when the supernova would appear again. Because the lensing causes a time shift, and we actually get to watch the same event more than once, which I think is so incredibly cool. They estimate that we see this supernova again sometime between 2015 and 2017. And in 2015, it appeared again. This allowed astronomers to predict additional appearances, and by 2018, astronomers had confirmed a half-dozen appearances of Supernova Refsdal. And this gave us a whole new way to calculate cosmic expansion. By using multiple observations of the same supernova event, we could calculate the actual distance of the lensed light. By comparing this to the apparent angular separation between appearances, the team could determine the true distance of the lensing galaxy, and comparing this to its redshift lets us calculate the Hubble parameter. This approach doesn't rely on either the distance ladder or the Cosmic Background Radiation, so it is a completely independent way to measure cosmic expansion. But we've got a sample size of 1. Now, masers are a little bit different. A maser is a laser, which is sourced with microwave radiation instead of visible light. And using the... Basically, water, which is orbiting a black hole as part of the accretion disk, can be measured, and as the disk is orbiting toward us, and one side is orbiting away from us, so there is the overall redshift of the galaxy with the black hole. And there's also a relative blue shift and redshift on either side of the black hole. Measuring the width between either side gives us the apparent size of the accretion disk. And the orbital speed gives us the actual size. Comparing these two gives us the distance to the black hole, and thus to the galaxy. So, the maser method gives us the same measurements as the supernova method, but it is completely independent. The maser result is between 72 to 77 kilometers per second per megaparsec. So, this result does overlap with the supernova method, but is even further from the Cosmic Microwave Background method. So, now I want to talk about the study we mentioned a few weeks ago, published in the *Monthly Notices of Royal Astronomical Society*, which claims that our estimates of the brightness of Type 1A supernova are wrong. The new data suggests that the younger the host galaxy, the dimmer that the Type Ia supernova will be. And this has huge implications. It suggests that the current Standard Model of Cosmology, the Lambda CDM model, is wrong. And their certainty of their findings are at Nine Sigma. So, according to this new research, the cosmic expansion isn't accelerating. In fact, it's been slowing down for about a billion years now. To be clear, the universe is still expanding, it's just not accelerating the rate of expansion over time. So, this means that cosmic expansion can't be entirely due to the structure of space and time. In general relativity, the Hubble parameter is an absolute universal constant. It can't vary in time and space, and it can't cause expansion to decelerate. So there's a lot more work to be done to verify these new findings and a whole bunch of new questions that get raised. I do believe that the Vera C. Rubin Observatory is going to play a major role in answering those questions and helping us to better understand the fate of the universe in the years to come, as we measure thousands more Type 1A supernova and calculate their host galaxy ages. So, that's the gist of where we are today, Jay. The Hubble tension may be actually resolved, but in a way that raises more questions, I think, than it answers.

**Jay Shaffer:** Yeah, it kind of seems to me it's kind of like in carpentry, we talk about sometimes you have an elastic measuring tape. Is that... this is kind of a... it seems that our actual ruler that we're using varies under these different circumstances and things that we're measuring. And so again, it has everything in flux, and it makes for lots of busy work for cosmologists in particular.

**Mike Lewinski:** Yeah, and I just I find it all very exciting. I'm looking forward to what we continue to learn. The difficulty, Einstein called the cosmological constant his greatest blunder and went and took it out, but then we had to put it back in. And it seems like when he called it his greatest blunder, he might have been onto something. And there's a whole side discussion about how tightly he clung to the cosmological constant in the face of contrary evidence. It wasn't just that he was wrong, it's that he was very, very sure in his wrongness.

**Jay Shaffer:** Yeah, and that's, yeah, just the kind of bigger picture of things, we always kind of I've known a person that was doing cosmological research and they said, in the end, we don't really have to worry about our results for a very, very, very long time. And so, we've got a little bit of time on our hands to resolve this Hubble tension.

**Mike Lewinski:** Indeed, we do. This has been a great series. I've really enjoyed everything I've learned. About attention.

**Jay Shaffer:** Well, yeah, and I've learned a ton, and I hope our listeners have as well, and so we'll have to find another equally fascinating series of topics to talk about in the up-and-coming episodes. So, let's go ahead and thank all of our listeners for checking out this podcast. Please be sure to comment, like, and subscribe, and let us know what you'd like to hear more about. You can also check out our individual websites. Mike's is at wildernessvagabonds.com, with some really great footage from the recent Aurora. And my site is skylapser.com. And if you'd like to help us out so that we can continue to do this podcast, you can buy us a coffee at [buymeacoffee.com/skylapser](https://buymeacoffee.com/skylapser). The intro music is Fanfare for Space by Kevin MacLeod from the YouTube Audio Library. From the Deep Sage Nine Observatory, this is Jay Shaffer, and wishing you all clear skies.

**Mike Lewinski:** Mike Lewinski. Jay, can I insert one last sentence, just to make sense of the maser story? Because I left out something really critical. And that is that an astronomical maser is created by the emission of microwave light, and we see this. The astronomical masers are produced by water that is orbiting a supermassive black hole at the center of a galaxy. And that gives you the redshift of the galaxy. So, I apologize for not having bungled that segment just a little bit. I jumped into the accretion disk without explaining that the maser is created by the water orbiting that black hole.

**Jay Shaffer:** Yeah, and do another sentence just to say a maser is like a laser, except that it uses microwave radiation. Okay.

**Mike Lewinski:** A maser is like a laser, except that microwave is the source of the radiation, and not visible light.