Welcome to the StarCast for the week of October 12th, 2025. I'm your host, **Jay Shaffer**, and with me is my co-host, Mike Lewinski. Good morning, Mike.

Hi, Jay, how are you doing?

Good\! I'm podcasting today from the **Space Coast in Florida**. And I'm hoping to get to watch a launch this evening of the KF-03 mission on a **Falcon 9** rocket. And it's kind of ironic that the payload is Kuiper satellites, and Kuiper is **Amazon's** communication satellite constellation. That's a direct competitor to SpaceX, and so, I thought that was kind of ironic. And then the last time I saw a launch here was when I was here during the last shuttle mission, **STS-135**, back in 2011, and so I actually watched the very, very last space shuttle go into space. And so, hopefully, the weather will cooperate this evening. And so, speaking of weather, let's take a look at space weather from SpaceWeather.com. Mike, what's up with the sun over the next couple days?

So, Jay, there is a **solar wind**, which is currently buffeting the Earth's magnetosphere, flowing from an equatorial hole in the sun's atmosphere. So, for the next day or so, as our planet moves deeper into the stream of solar wind, we have a chance of **G1-class geomagnetic storms**. And it looks like my forecast is clearing tonight, so I may have an opportunity to capture that. We're currently sitting at a K-index of around 3.6, which is still in the quiet range. However, our chances of active conditions are 40-45% here in mid-latitudes over the next 48 hours. And with a 25% chance that we'll see a minor geomagnetic storm. If you're up at higher latitudes, you can see 65% chance of severe storm in the next 24 hours, 60% over the next 48 hours. So, we definitely have a chance of **Aurora**. And I am crossing my fingers I get a little bit of Northern Lights to capture in my time lapse.

Yeah, great, and yeah, since it's a waning gibbous moon, you might be able to catch it, especially if it's early in the evening. And so, the last... What's that?

Yes. So what's happening in the night sky? What else is happening in the night sky this week?

Well, we've got the **last quarter moon** is gonna fall at exactly 1:13 PM Central Daylight Time on Tuesday, October 14th, 2025. And so, in this last quarter, the moon will rise just after midnight on your local time, and set around noon. So, look for it high in the sky before dawn. Early in the week, the moon will lie between the bright stars **Betelgeuse**, **Capella**, and **Aldebaran**. So, you can it'll be right in the middle of those three bright stars. And Betelgeuse, of course, is the giant red star that you see. Capella is kind of interesting in that it kind of shifts colors between warm colors, reddish and bluish, and so it twinkles more than most other stars. And then Aldebaran is also another white, bright star, and it is basically the **eye of the bull in Taurus**. And then, later in the week, the third quarter moon will lie near bright **Jupiter**, and the twin stars of Gemini, **Castor and Pollux**. Also, the **comet Lemon** (or I don't know if it's Lemon or Le Mans) is brightening in our northern sky near the Big Dipper. Right now, it's visible with a small telescope or a telephoto lens, and I was able to image it last week. But it might be visible to the naked eye in the next week, and it's promising to be the brightest comet of the year, so keep an eye out for that. So now, let's take a look at some space news. Mike, what do you got?

So, Jay, there is a new study reported about a decade of data collected by a radio telescope in **Australia** that is revealing how the early universe is warmer than expected during the **epoch of re-ionization**. This was a critical stage in the Cosmos' evolution, when neutral hydrogen atoms began to pick up extra electrons and become ionized. And this caused the universe to transition from a stage of opacity to transparency, when light could actually begin to travel through the universe instead of immediately being absorbed in the plasma that was present during previous epochs. So, with this study, astronomers from the **Murchison Widefield Array Radio Telescope** learned that the fog of hydrogen gas between galaxies that was expected to be extremely cold, some 800 million years after the Big Bang, must have been previously heated. This discovery rules out models which predict an extremely cold universe at the time. And it is believed that the warmth is due to sources of **X-rays**, such as nascent black holes or remnants of dead stars that would have provided the necessary energy to heat this intergalactic gas. The authors are clear that they did not detect heat. They simply determined that the hydrogen line is not demonstrating the presence of or the absence of heat during that time. So the models that we create from that radio telescope array are showing that a cold universe could not have created what we see at this time. Research is published in two papers in the **Astrophysical Journal** and relied on a painstaking analysis and cleaning of 10 years of radio data. The team, including researchers from the **Curtin Institute of Radio Astronomy**, had to use innovative methods to strip away all of the foreground signals, such as emissions from nearby galaxies, from the Earth's atmosphere and from the telescope itself, in order to isolate the faint signal from the epoch of reionization. Having successfully processed the data and determined that the universe was warmer than anticipated, the team plans to apply their advanced data analysis techniques to the upcoming and more powerful **Square Kilometer Array** telescopes to further refine their understanding of this pivotal era. So, Jay, how does this news story relate to our topic today?

Well, did you know that you can you may have a radio telescope in your living room? If you have an old-fashioned TV, or modern TV that has an antenna input, some of the static that you see on those unused channels when the snow is on the TV, is actually what we call **cosmic microwave background radiation**. Some folks even call it the sound of the Big Bang. In essence, when you saw that speckled static on an analog TV, you were literally seeing a bit of the light release from the beginning of the universe, about 13.8 billion years ago, so just about the time that we're talking about in this news story. And so, that basically, we can look at that noise from about that exact same time as we talked about in the news story. So, Mike, can you tell us a little bit more about Cosmic Microwave Radiation, and answer the question: can it make popcorn?

Well, I'm afraid it's not strong enough to make popcorn today, Jay. Although, if we could go back in time, there would be so much light from the Cosmic microwave background, that the sky the night sky would shine as brightly as the sun. This was when before the universe had expanded to its current size. So, there is a tremendous amount of energy there. In fact, Cosmic microwave background radiation contains the vast majority of the photons in the universe by 400 to 1 factor. The number density of photons in the **CMB** is about 1 billion times the number density of matter in the universe. And so, total energy density of CMB exceeds all of the photons emitted by all of the stars in the history of the universe. It is truly a tremendous amount of energy. But before we go any further, I'd like to play a sound for you, Jay. You mentioned the sound of the Big Bang heard in the hiss of static on a television, and I want to just point out that so we see about 1% of the pixels and snow on a television are estimated to come from the Cosmic microwave background, and that would also be true from the sound that you're hearing. But this is, of course, the receiver picking up some of those electrons and then converting them into the light pixels of snow on TV, or the hiss of static in the radio signal. So it's it's really an amplification of or simulation of what that is. I'm gonna play a different simulation. Now this is about 20 seconds of audio, and this is basically a representation of the first 760,000 years of the evolution of the universe in audio format. So here we go. (Audio plays) All right. So, Jay, what you just heard...

So that's sort of like...

And you may, you may need to embed the we'll include in our show notes a link to **John G. Kramer**, who is the physicist who compiled this sound. He works at the University of Washington in Seattle. And if you can listen to it after our episode and decide if what was recorded here on our call was true fidelity. But that sound is it's it's a representation, but I want to make clear that the Cosmic Microwave background radiation is both **light and sound**. So when the Universe hit the period of what we call a **recombination**, which is something of a misnomer. There was no previous combination, but we're talking about the time when the first protons and electrons in the universe were combining together and creating **hydrogen atoms**. And as a result of that, there was **photon decoupling**, where the combination of electrons and protons releases photons. And the motion of those photons is also creating a compression of the plasma, the soup of protons, leptons, electrons, in the early universe in its opaque phase. And those waves are compressing the matter of the universe in almost exactly the same way that a sound wave is a compression of air that our eardrums detect and translate into sound. So, Cosmic microwave background radiation is both light and sound. The sound is not just a metaphor. Although I will say that it would not have been audible if there was a human ear in the first 760,000 years of the universe. The sound would have been too quiet to actually hear it. So this was a simulation that is amplified. But nonetheless, that is how the first 760,000 years would have progressed in audio. So, the cosmic microwave background radiation is the **oldest thing that we can detect**. It is the **fossil imprint** from the birth of the universe. And yes, when we turn that analog television into an empty channel, we're picking up some of that. CMB tells us a story about simplicity of that early plasma evolving into the complexity of the giant structures of galaxies, stars, planets, and everything else that we know about in the universe. Including you and me. This is an echo of creation that is still ringing across the universe today. And we gain important information about the history of the universe, the structure of the universe, by measuring cosmic microwave background. We are able to determine the overall curvature of the universe from the first peak of the power spectrum when we map the microwave background radiation. The second peak and third peak tell us about the density of **normal matter** and so-called **dark matter**, respectively. So to get the really fine details of what is there in this fossil is challenging because of changes that have happened, and emission by the foreground features, such as galaxies and stars. It is important to remember that as the universe is expanding, so is the cosmic microwave background radiation itself. So we said that during the period of recombination, photons and electrons combine and emit photons. Those photons have been **stretched out** until they are now in the **microwave spectrum**.

Yeah, that that's yeah, that's exactly what I was going to ask you is about the **Redshift** and the fact that when those when those photons originated, they were probably in the visible light spectrum, if not maybe even further up the spectrum into ultraviolet or something like that. And so, basically, over time, they've red-shifted into the microwave. Is that an accurate description of...

It is. And we talk about the **CMBR is isotropic**, meaning that it is remarkably uniform across the sky. However, there is anisotropic, or variations in, as we measure in direction. And so you will probably see maps, and we can include a link to one of the CMBR as viewed from our radio telescopes. And there are brighter and darker areas that are basically the structure of the universe itself. And with that, we get the ability to make projections of what the structure of the early universe must have looked like. So, for example, with this Curtin observatory studies that have been published, we're now gaining evidence that there were probably some black holes or stars that had existed prior to the re-ionization phase. Because the evidence of the structure is that the universe could not have been as cold as some of the models say it was, and if it was not that cold, then it must have been due to the fact that there were sources of heat, such as the black holes or stars. Black holes emitting X-rays that would have heated the primordial universe, and we're definitely going to get more information about this as time goes on. So, one of the one of the important aspects of studying Cosmic microwave background radiation, is that we get the ability to determine how **fast the universe is expanding**, and how **dense the universe is**. And from those, we can make projections of: Is the universe going to expand forever, or will it reach a point where it starts to collapse back in on itself and ends in a **big crunch**? And it looks currently like expanding forever is the most likely scenario. Now, I will say, we're talking about cosmic microwave background radiation this week. And we're going to continue to set the stage in upcoming episodes so that we can eventually discuss what's called the **Hubble tension**. So, probably next week, we'll be talking about **Cepheid variables** and revisiting the **cosmic distance ladder**, which we talked about in a previous episode. And then we'll need to have at least one episode about dark matter and **dark energy** before I think we've set enough of the stage to really even have a conversation about Hubble tension. And I will say that I've spent the last day reading about cosmic microwave background, and I feel like I get maybe 2% of the importance and details. I find myself just proliferating with new, new pages to, oh, now I need to learn about the Thompson scattering. Oh, now I need now I need to learn about the period of epoch of reionization, and it's just one rabbit hole takes me down another, and so this is all very tricky to get a handle on, and I feel like I'm only about 5% of my way with the Cosmic Microwave background. But just to kind of give you a quick preview, the Hubble tension is what happens when our measurements of CMB, which are extremely precise and have a very small margin of error, conflict with other local measurements of the motion of galaxies. And basically, the Cosmic microwave background says that the universe is moving expanding at one rate, and the other measurements, including with Cepheid variables and the cosmic Distance Ladder, says that the universe's expansion is at a different rate. And when we first started to do this science, the margin of error for both sets of measurements was within the range of the other. And so people said, okay, well, we're in the right neighborhood. But now, we have made such advances with our instrumentation and with the math, which so much of this comes down to the math of filtering out the noise and the signals and making ever greater advances with how we calculate motion, that we're no longer in the discrepancy between the two types of measurements is no longer within the margin of error of each other. And so, is our understanding of CMB in error? is our understanding of the cosmic distance ladder in error? And we seem to only be getting more precise measurements out of both systems, and they don't agree with each other. So something has to give. And I think that's going to be a fun episode when we get to it.

Yeah, and so, yeah, I wouldn't throw a couple things at it. So this is there's various areas of people that study astronomy, and there's people that study black holes, and there's people that study exoplanets, like some astronomers we talk to in earlier episodes. And so this is in the kind of the science of **cosmology**, and cosmology has nothing to do with makeup. And so the cosmology is the study of the universe, or the early universe, or the universe as a whole. And this is what it's being currently called the **crisis in cosmology**. And it's kind of funny that I've talked to several other scientists and astronomers, and it's kind of like they're in their own little niche of study, but they're, like, looking over the fence at the cosmologist and going, man, I don't envy your position right now, because basically, they're throwing out years and years of science here that people are going to have to reconstruct. And also, I was trying to make a more simple analogy for cosmic background radiation. And I've always come, I always kind of think of our universe as a **bubble**, and so it's kind of like if we were on the surface, inside surface of a bubble, looking at the other surface of the bubble is kind of how we see cosmic background radiation. Do you think that that's a kind of a roughly accurate analogy, Mike?

Yeah, I think that we can we can use that as a as a starting point for how we envision it. It's important to understand, too, that, and this has to do with Hubble's contribution, that the further away things are from us, the **faster they are moving away from us**. And so, that other side of the bubble is being the furthest part away from us is moving the fastest.

Yeah, and it's also the **furthest back in time**, and so and that goes to maybe things were accelerating faster earlier in time, and as time goes on, the acceleration decreases. And I just wanted I think I had some rough numbers. Previously, the Hubble constant was that the university was expanding about 62 million kilometers per second. And some of the new models are in the 73 million kilometers per second.

Per second, per second, per megaparsec, right. And so it's a, at something like 1 megaparsec galaxy is moving at 70 million kilometers per second, I think. That's how that sort of gets quantified.

Yeah, so we're talking a difference of somewhere in the area of **5%** is the discrepancy, right?

Yes, exactly.

Okay. And anything else you want to add to the understanding cosmic background radiation for today's episode?

I think it's important to make the point that when we talk about the background radiation, we're talking about what they call the **Black Body Temperature**. And so temperature is the motion of matter. Atoms and molecules, the faster the atoms are moving, the warmer something is, whether we're talking about the temperature of the air, of the water or of space itself. And so, when we measure microwave radiation, we're measuring in units of **Kelvin**. And the wavelengths of the CMB is approximately 1.9 millimeters. And that corresponds to a temperature of **2.725 Kelvin**. So that's just above **absolute zero**, and absolute zero is the temperature at which there is zero motion of atoms, zero motion of molecules. No, nothing moves at absolute zero. And of course, it was much, much, much more energetic in the early universe, when the universe was smaller and denser. And you can imagine that if we're talking about temperature being a function of the motion of atoms together, that as the universe is expanding, the universe is becoming less dense, and the implication there is that it must cool. Atoms can't bump into each other as often as the space between them increases. And it's not just that they are moving apart from each other, it's that the space that they are in is growing, and so the distance between them is growing without any other motion taken into account. So, that temperature of 2.725 degrees Kelvin is a very important measurement. And it is one of science's great successes, that the theory of the **Big Bang** is tested by and demonstrated by our measurements of the Cosmic microwave background, and that temperature. And the formula that we have to prove that this is what we get from the expected phases of the universe that cosmology has discovered. It seems to be holding up extremely well. And so, how we ultimately resolve that tension is I'm not smart enough to even begin to hazard a guess, because I believe that the measurement of the CMB is accurate, and I believe that the measurement of the local motions are accurate. And getting more accurate over time, and so something has to give. And maybe we're gonna come out with some fantastic new physics that resolves this discrepancy. Something to do with dark energy, perhaps. I do not know, but I'm eagerly awaiting progress.

Yeah. Yeah, and so this is also when you talk about absolute zero and getting down to where matter does not move. This also then that gets us into the area of **quantum mechanics** as well, and so going from the very largest thing, the universe, to the very smallest thing that we know, which is in the quantum realm. So, there's a connection there. And then also the one last thing I wanted to note, if we were talking about the infinitely expanding universe, and like you said, also infinitely cooling, is that when we get to the at some point in the future, we're going to get to a state where stars cannot, or galaxies can no longer see each other, is that they're expanding so far apart, and they're moving apart further than the light can reach them. And so, in a far future galaxy, they may not be able to see any other galaxies, and so they may not actually have that window into the past that we have. And maybe the only thing that they would be able to see would be that cosmic background radiation. Think about that.

Yeah. Jay, we should talk about **Olbert's Paradox** on a future episode.

Okay. All right, well, we're gonna run out of time today, so that was fascinating, Mike. Thank you so much, and we want to thank all of our listeners for checking out this podcast, and be sure to comment, like and subscribe, and let us know what you'd like to hear more about. And you can also check out our individual websites. **Wildernesspagabonds.com** is Mike's, and you can check out my site at **skylapser.com**. And if you'd like to help us out, we're kind of short on coffee, so you can buy us a coffee at [buymeacoffee.com/Skylapser](https://www.google.com/search?q=https://buymeacoffee.com/Skylapser). Our intro music is Fanfare for Space by Kevin McLeod from the YouTube Audio Library. From the Deep Sage 9 Observatory, or the Space Coast of Florida. This is Jay Shaffer, and Mike Lewinski wishing you all clear skies.