Speaker 1: Welcome to Bedtime Astronomy. Explore the wonders of the cosmos
Speaker 1: with our soothing Bedtime Astronomie podcast. Each episode offers a
Speaker 1: gentle journey through the stars, planets, and beyond, perfect for
Speaker 1: unwinding after a long day. Let's travel through the mysteries
Speaker 1: of the universe as you drift off into a peaceful
Speaker 1: slumber under the night sky.
Speaker 2: If you want to find the next Earth, like a
Speaker 2: literal second home for humanity out there in the galaxy, yeah,
Speaker 2: the absolute worst place you could look is right around
Speaker 2: a star that looks exactly like our son.
Speaker 3: I mean, which sounds completely backward, right, because for decades
Speaker 3: that was the whole strategy, right.
Speaker 2: You assume you wanted a carbon copy of our solar system. Yeah,
Speaker 2: a nice, stable yellow Sun and a rocky little planet
Speaker 2: just sitting at the exact right distance exactly.
Speaker 3: But the data has completely forced us to basically tear
Speaker 3: up that playbook. Finding a twin of Earth around a
Speaker 3: twin of the Sun is just well, with our current
Speaker 3: tach it's practically.
Speaker 2: Impossible, which is so frustrating. But that's why today we're
Speaker 2: talking about venturing into I guess you could call it
Speaker 2: the cosmic graveyard.
Speaker 3: Yeah, that's a good way to put it.
Speaker 2: We're looking at these things called failed stars, and we're
Speaker 2: getting into all this because of a Canadian space mission
Speaker 2: called POOAA, which is launching in twenty twenty nine.
Speaker 3: Right, and POUAIT is totally abandoning the blinding light of
Speaker 3: those bright yellow suns. It is a highly optimized, really
Speaker 3: aggressive strategy to search in the shadows basically.
Speaker 2: Okay, so let's lay out the scoreboard first, because the
Speaker 2: numbers here they really tell a super frustrating story for astronomers. Oh, absolutely, right, Now,
Speaker 2: humanity has confirmed nearly six thousand, three hundred exoplanets.
Speaker 3: Which is just a staggering number to even think about.
Speaker 2: It's massive. Just pause and think about that. Over six
Speaker 2: thousand alien worlds orbiting other stars that we know exists
Speaker 2: for sure. But out of that huge catalog, only two
Speaker 2: hundred and twenty three are actually designated as terrestrial.
Speaker 3: Right, meaning they're rocky planets with a solid surface like
Speaker 3: Earth or Mars.
Speaker 2: Yeah, it's two hundred and twenty three. So you look
Speaker 2: at a ratio like that and it's like, what roughly
Speaker 2: three percent roughly.
Speaker 3: Yeah, it's so.
Speaker 2: Easy to jump to the conclusion that rocky planets are
Speaker 2: just as super rare anomaly in the universe.
Speaker 3: But that is a total trap. You really can't look
Speaker 3: at it that way.
Speaker 2: Really, why not, Because.
Speaker 3: The vast majority of those six thousand worlds are gas
Speaker 3: giants or ice giants. There are these massive, bloated planets
Speaker 3: that don't even have a solid surface, right, So.
Speaker 2: We're talking about places like Jupiter or Neptune.
Speaker 3: Exactly, environments where the atmospheric pressure is so intense it
Speaker 3: would you know, it would literally crush anything long before
Speaker 3: it ever reached some hypothetical core.
Speaker 2: So the fact that we have thousands of gas giants
Speaker 2: and barely any rocky ones.
Speaker 3: It tells us practically nothing about what's actually out there
Speaker 3: in the universe, But it tells us absolutely everything about
Speaker 3: the limitations of our own telescopes.
Speaker 2: Okay, so it's classic selection bias. It's like, uh, if
Speaker 2: you drag a huge fishing net through the ocean, but
Speaker 2: the net has these massive holes in it right right,
Speaker 2: you pull it up, You're like, wow, the ocean only
Speaker 2: contains giant tuna, but really all the small fish just
Speaker 2: slipped right through the gaps.
Speaker 3: That's a perfect analogy. The tools we rely on are
Speaker 3: heavily biased toward finding the loudest, biggest things in the room.
Speaker 2: Okay, so unpack that for us. Why are our tools
Speaker 2: so biased?
Speaker 3: Well, it comes down to the physics of exoplanet detection.
Speaker 3: Planets don't emit their own light, right, at least not
Speaker 3: in the visible spectrum. They only reflect the light of
Speaker 3: their host star.
Speaker 2: Right, there's just bouncing light back at us.
Speaker 3: Yeah, So direct imaging, like actually pointing a telescope and
Speaker 3: taking a photograph of a planet, is unbelievably difficult. It's
Speaker 3: like trying to photograph a firefly buzzing right next to.
Speaker 2: A lighthouse from like fifty miles away.
Speaker 3: Exactly, the glare from the lighthouse the star just completely
Speaker 3: washes out the tiny speck of light from the planet.
Speaker 2: So if we can't just take a picture of them,
Speaker 2: how are we finding thousands of them?
Speaker 3: We have to rely on indirect methods we observe the
Speaker 3: effect that the planet has on its star. Historically, we
Speaker 3: leaned really heavily on something called the radial velocity method.
Speaker 2: A radio velocity Okay, what is that? In plain English?
Speaker 3: It's basically measuring a microscopic wobble as a planet orbits
Speaker 3: a star. It's gravity actually tugs on the star a
Speaker 3: little bit and makes the star wobble back and forth
Speaker 3: in space.
Speaker 2: Oh wow, so the star is actually moving.
Speaker 3: Just a tiny bit. Yeah. And obviously a massive bulky
Speaker 3: gas giant like Jupiter is going to yank on that
Speaker 3: star a lot harder than a tiny speck of rock
Speaker 3: like Earthwood.
Speaker 2: So the wabble is bigger.
Speaker 3: The wabble is much bigger. The Doppler shift in the
Speaker 3: starlight is way more pronounced, and our telescopes can catch
Speaker 3: that signal pretty easily.
Speaker 2: Okay, that makes total sense. Big planet equals big wobble
Speaker 2: equals easy to spot. But what about the other method,
Speaker 2: the one that really blew the doors open.
Speaker 3: You're talking about the transit method.
Speaker 2: Yeah, the transmit because that's what the Kepler mission used.
Speaker 3: Right exactly. Kepler changed everything. And the transit method is
Speaker 3: conceptually super simple. It's just an eclipse.
Speaker 2: So a planet just passes in front of the star.
Speaker 3: Right, It passes directly between our telescope and the host star,
Speaker 3: and it blocks a tiny, tiny fraction of the starlight.
Speaker 2: Okay, but let's run the numbers on that, because I
Speaker 2: feel like people underestimate how hard this is if we
Speaker 2: take an Earth sun analog.
Speaker 3: Okay, let's do it.
Speaker 2: Let's say there's an alien astronomer hundreds of light years
Speaker 2: away staring at our Sun and hoping to catch the
Speaker 2: Earth transitting. Right, how much light does the Earth actually block?
Speaker 3: About zero point zero percent.
Speaker 2: One hundredth of one percent.
Speaker 3: Exactly one hundredth of one percent of the Sun's total light.
Speaker 3: And here's the kicker. That dip only happens once a year.
Speaker 2: Because our orbit takes a year, right.
Speaker 3: And the transit itself only lasts for a few hours.
Speaker 2: That is insane. It's literally like trying to detect a
Speaker 2: single moth flying in front of a stadium spotlight from
Speaker 2: miles of miles away. Yes, and you're doing it purely
Speaker 2: by measuring the drop in the spotlights overall glare.
Speaker 3: Which is incredibly hard. And to make it worse, you
Speaker 3: can't just spot it once to actually confirm an orbit.
Speaker 3: You need to see multiple transits.
Speaker 2: You're waiting years and years just to verify a.
Speaker 3: Signal, years, and you're looking for a signal that is
Speaker 3: barely distinguishable from background static.
Speaker 2: The static. Let's talk about the static, because the stars
Speaker 2: themselves are not making this easy for us.
Speaker 3: Not at all. Stars are not uniform perfectly static light bulbs.
Speaker 3: They are violently churning spheres of plasma. Right, They have
Speaker 3: massive sunspots that rotate into view, and those sunspots are dark,
Speaker 3: so they block light and actually mimic a planetary transit.
Speaker 2: Oh so a sunspot can look like a fake planet exactly.
Speaker 3: Plus they have solar flares and internal pulsations that cause
Speaker 3: their brightness to wildly fluctuate all the time.
Speaker 2: So you're trying to find a zero point zero one
Speaker 2: percent dip caused by an Earth sized planet amidst all
Speaker 2: this chaotic, boiling stellar noise.
Speaker 3: It's an immense challenge. But conversely, if you're a looking
Speaker 3: at a Jupiter sized planet around a sun like star,
Speaker 3: it blocks about one whole percent of.
Speaker 2: The light, which is huge by comparison.
Speaker 3: Right, that is a massive, unmistakable signal compared to the
Speaker 3: noise floor.
Speaker 2: Okay, so knowing all of this, the need for a
Speaker 2: specialized tool becomes super obvious. If the fishing net has
Speaker 2: holes that are too big, you don't just keep casting
Speaker 2: it over and over hoping for a miracle.
Speaker 3: No, you build an entirely different net.
Speaker 2: Which brings us to the entire driving philosophy behind the
Speaker 2: POET mission. Yes, poet T it stands for Photometric Observations
Speaker 2: of Exoplanet Transits. Like we said, it's a Canadian microsatellite
Speaker 2: launching in twenty twenty nine and its sole purpose is
Speaker 2: to find Earth size and super Earth exoplanets.
Speaker 3: But the brilliant thing is they aren't trying to achieve
Speaker 3: this by building some monstrously huge mirror.
Speaker 2: Right, because building a bigger camera to stare at the
Speaker 2: same stadium spotlight doesn't actually solve the fundamental contrast problem,
Speaker 2: right exactly.
Speaker 3: The genius of po is that it changes the spotlight itself.
Speaker 2: Okay, explain that how do you change the spotlight?
Speaker 3: Instead of looking at G type yellow dorks like our sun,
Speaker 3: the mission is targeting what astronomers classify as ultracool dwarfs.
Speaker 2: Ultracool dwarfs.
Speaker 3: Okay, So, going back to your analogy, if you swap
Speaker 3: out that massive stadium spotlight for a dim, little.
Speaker 2: Desk lamp, oh I see where this is going.
Speaker 3: Right, and that same moth flies in front of the
Speaker 3: desk lamp, the percentage of light that gets blocked absolutely skyrockets.
Speaker 2: Because the background light is so much smaller.
Speaker 3: Exactly, the fractional dip in brightness goes from that imperceptible
Speaker 3: zero point zero one percent to a highly measurable one
Speaker 3: percent or even more.
Speaker 2: That is such a clever hack. So let's really dig
Speaker 2: into what makes a star an ultra cool dwarf, because
Speaker 2: targeting the runts of the stellar litter is just a
Speaker 2: fascinating approach.
Speaker 3: To me, it's the best strategy we have right now.
Speaker 2: So when we look at the stellar classification system, it's
Speaker 2: essentially a temperature scale, right, that also correlates with mass
Speaker 2: and size.
Speaker 3: That's right, Our sun is a G type star. K
Speaker 3: type stars are a little bit smaller, they're cooler, and
Speaker 3: they glow with a slightly orange hue.
Speaker 2: Okay, and M type M.
Speaker 3: Type stars are the red dwarfs. They're even smaller and
Speaker 3: cooler still. But then you get to the bottom of
Speaker 3: the barrel, the brown dwarfs.
Speaker 2: And these are the ones Pew is specifically hunting. The
Speaker 2: literature always refers to brown dwarfs as failed stars. Yes,
Speaker 2: what does that actually mean? What are the physical mechanism
Speaker 2: of a star failing?
Speaker 3: To understand the failure, you really have to look at
Speaker 3: how a star is born. In the first place, A
Speaker 3: star begins as this massive collapsing cloud of hydrogen, gas
Speaker 3: and dust.
Speaker 2: Right, gravity is just pulling everything together.
Speaker 3: Exactly as gravity pulls all that material inward, the pressure
Speaker 3: and the temperature at the very core begin to styrocket,
Speaker 3: and if the collapse in cloud has enough mass, the
Speaker 3: core temperature reaches a critical threshold, which.
Speaker 2: Is what like millions of degrees.
Speaker 3: Around ten million degrees celsius. At that point, the kinetic
Speaker 3: energy of the hydrogen atoms is so ridiculously high that
Speaker 3: they actually overcome their nat electromagnetic repulsion.
Speaker 2: They stop pushing each other away, right.
Speaker 3: They slam together, and they fuse into helium. This is
Speaker 3: nuclear fusion, and it releases a staggering amount of energy.
Speaker 2: Like billions of nuclear bombs going off.
Speaker 3: Constantly, pretty much, and the outward pressure from that continuous
Speaker 3: nuclear explosion perfectly balances the inward crush of gravity. When
Speaker 3: that balance is achieved, a true star ignites.
Speaker 2: But a brown dwarf just doesn't have the gravitational muscle
Speaker 2: to reach that ignition point precisely.
Speaker 3: That is the issue. A brown dwarf gathers a substantial
Speaker 3: amount of mass, far more than a gas giant like Jupiter,
Speaker 3: but it falls agonizingly short of the mass required to
Speaker 3: trigger sustain hydrogen fusion.
Speaker 2: So it gets super hot, but it never quite catches fire.
Speaker 3: Right. The core gets incredibly hot, and it might briefly
Speaker 3: fuse some deterium, which is like a heavier isotope of hydrogen,
Speaker 3: but it can't maintain the main event.
Speaker 2: So if it doesn't have that outward nuclear explosion, why
Speaker 2: doesn't gravity just crush it into a black hole or something.
Speaker 3: What stops the c is actually this bizarre quantum mechanical
Speaker 3: phenomenon called electron degeneracy pressure.
Speaker 2: Electron degeneracy pressure that sounds intense.
Speaker 3: It is basically, the electrons in the core physically refuse
Speaker 3: to be squeezed any tighter. It's a fundamental rule of
Speaker 3: quantum physics.
Speaker 2: So it's just trapped in this weird middle ground.
Speaker 3: Exactly. It's too massive to be a regular planet, but
Speaker 3: it completely lacks the nuclear engine to be a true star.
Speaker 3: It just sits there, glowing faintly from the residual heat
Speaker 3: of its own gravitational collapse, like a dying ember. Yes,
Speaker 3: just slowly cooling off over billions of years.
Speaker 2: And because they lack that internal engine pushing outward. Brown
Speaker 2: dwarfs and even the smallest M type red dwarfs are
Speaker 2: physically tiny compared to our Sun.
Speaker 3: Right, Oh, incredibly tiny. An ultra cool dwarf is roughly
Speaker 3: ten percent of the Sun's diameter.
Speaker 2: Ten percent, So in terms of actual physical volume, how
Speaker 2: big is that?
Speaker 3: They are barely larger than Jupiter?
Speaker 2: Wow? Okay, So that brings the desk lamp analogy into
Speaker 2: sharp mathematics. Because the surface area of a star is
Speaker 2: proportional to the square of its radius, right right, So
Speaker 2: if you shrink the star's diameter to ten percent of
Speaker 2: the suns, its surface area actually shrinks to just one percent.
Speaker 3: Of the signs exactly. You put an Earth sized planet
Speaker 3: in front of that tiny surface area, and suddenly it's
Speaker 3: casting a massive shadow relative to the star's total output.
Speaker 2: You've completely rewritten the geometry of the transit. You've skewed
Speaker 2: it to favor finding small, rocky worlds.
Speaker 3: It's an elegant hack of astrophysical geometry. Honestly, you maximize
Speaker 3: the planet to star size ratio by creating that drastically
Speaker 3: higher contrast. You can use a relatively small, cost effective
Speaker 3: instrument in space to detect signals.
Speaker 2: It signals that normally you'd need what a massive, billion
Speaker 2: dollar telescope.
Speaker 3: To see exactly. It lets you do incredible science on
Speaker 3: a budget.
Speaker 2: Cost effective is definitely the operative phrase there, because the
Speaker 2: PA team isn't starting from scratch on this hardware.
Speaker 3: No, they have a huge head start, right.
Speaker 2: They are building on the legacy of these previous Canadian microsatellites,
Speaker 2: specifically one called MOST which launched back in two thousand
Speaker 2: and three and Neosat, which launched in twenty thirteen.
Speaker 3: Right, And when people hear the word satellite, they usually picture,
Speaker 3: you know, a school bus covered in gold foil.
Speaker 2: Yeah, something massive floating around.
Speaker 3: But microsatellites are a different breed entirely. They're essentially the
Speaker 3: size of a suitcase or maybe a small washing machine.
Speaker 2: A washing machine in space.
Speaker 3: Basically, but the science they yield is entirely disproportionate to
Speaker 3: their physical footprint. Take MOST for example, it stood for
Speaker 3: Microvariability and Oscillations of Stars.
Speaker 2: Which sounds very complicated. What was it actually trying to do?
Speaker 3: Initially it was designed for astro seismology. Okay, so studying
Speaker 3: starquakes exactly, studying the acoustic waves bouncing around inside stars
Speaker 3: to determine their age and what they're made of. But
Speaker 3: it proved to be so incredibly precise that the team
Speaker 3: actually pivoted it to exoplanet research and.
Speaker 2: It ended up making a huge discovery.
Speaker 3: Oh, one of the most foundational discoveries in early exoplanet
Speaker 3: atmospheric science. O.
Speaker 2: Yeah, I want to get into this because this discovery
Speaker 2: involved a hot Jupiter exoplanet orbiting a star called HD
Speaker 2: twenty zero nine four five eight kitchen name super catchy.
Speaker 2: So most observe this system and discover that this massive,
Speaker 2: blistering planet had a remarkably low albedo.
Speaker 3: Right.
Speaker 2: And albedo is just the measure of reflectivity, So like
Speaker 2: Earth has an albedo of about zero point three, meaning
Speaker 2: it reflects thirty percent of the sunlight that hits it.
Speaker 3: Mostly because of our clouds and ice caps.
Speaker 2: Right. But what most found was that this hot Jupiter
Speaker 2: was absorbing almost everything.
Speaker 3: It was darker than fresh asphalt. It had an albedo
Speaker 3: nearing absolute zero.
Speaker 2: This is so weird to think about a giant, pitch.
Speaker 3: Black planet, right because prior to that observation, there was
Speaker 3: this working assumption that hot jupiters might have highly reflective
Speaker 3: bright cloud decks, you know, maybe made of silicates or
Speaker 3: these exotic chemical compounds.
Speaker 2: Like Venus, but way bigger and hot.
Speaker 3: Exactly, Venus is super bright. But most proved that the
Speaker 3: atmosphere of this specific hot Jupiter was absorbing the star's
Speaker 3: energy directly.
Speaker 2: So what does a pitch black atmosphere actually look like? Chemically?
Speaker 3: It suggested a clear, totally cloudless upper atmosphere where alkali
Speaker 3: metals things like sodium and potassium were just absorbing all
Speaker 3: the visible light. Or perhaps it had incredibly dark light
Speaker 3: absorbing particulate hazes.
Speaker 2: So it's basically covered in cosmic.
Speaker 3: Smog pretty much. And that single finding forced atmospheric modelers
Speaker 3: to completely rethink how energy is deposited and circulated in
Speaker 3: these extreme.
Speaker 2: Environments, all from a suitcase sized satellite exactly. Then you
Speaker 2: had neosat follow up a decade later, tracking near Earth
Speaker 2: asteroids in space Debray, and both of these missions achieved
Speaker 2: world class science using telescopes that were only fifteen centimeters
Speaker 2: in diameter.
Speaker 3: Which is tiny.
Speaker 2: It's literally a six inch mirror. You can buy larger
Speaker 2: telescopes at a hobby shop.
Speaker 3: You really can.
Speaker 2: So now Pubitty is bumping that up to a twenty
Speaker 2: centimeter telescope, which is, you know, slightly bigger. But the
Speaker 2: real leap isn't just the size of the mirror.
Speaker 3: Is it, No, not at all. The real upgrade is
Speaker 3: the wavelengths of light it's engineer to actually see.
Speaker 2: Right, because most in neosat worked invisible.
Speaker 3: Light like our eyes do.
Speaker 2: But POET is expanding into the near ultraviolet, visible, near infrared,
Speaker 2: and short wavelength infrared.
Speaker 3: And that shift into the infrared is absolutely non negotiable
Speaker 3: given the targets they're going after.
Speaker 2: Because they're looking at those ultra cool dwarfs.
Speaker 3: Right, If you look at an ultracool dwarf invisible light,
Speaker 3: you're essentially looking at a blank wall. They emit incredibly
Speaker 3: little visible radiation.
Speaker 2: Why is that? Why are they so dim visually?
Speaker 3: It comes down to Ween's displacement law. It's a fundamental
Speaker 3: principle of thermal radiation. Basically, it states that the wavelength
Speaker 3: at which an object emits the most light is inversely
Speaker 3: proportional to its temperature.
Speaker 2: Okay, let's break that down.
Speaker 3: Sure, so our sun burns at roughly fifty five hundred
Speaker 3: degrees celsius, right, because of that specific temperature. Its peak
Speaker 3: emission is right in the middle of the visible spectrum
Speaker 3: yellow green light, which.
Speaker 2: Is why our eyes of all to see that specific
Speaker 2: light exactly.
Speaker 3: But brown dwarfs and red dwarfs are vastly cooler. Their
Speaker 3: surface temperatures might only be two thousand or maybe three
Speaker 3: thousand degrees, so.
Speaker 2: They aren't burning nearly as hot.
Speaker 3: Because they are cooler, the peak of their emission spectrum
Speaker 3: shifts heavily to the right. It moves entirely out of
Speaker 3: the visible spectrum and deep into the infrared.
Speaker 2: Oh I see.
Speaker 3: So if you want to study these stars, and more importantly,
Speaker 3: if you want to capture enough photons from them to
Speaker 3: measure a one percent dip when a planet transits, you
Speaker 3: have to tune your instrument to the frequency they are
Speaker 3: actually broadcasting on.
Speaker 2: You have to speak your language right.
Speaker 3: You need sensors capable of detecting heat radiation.
Speaker 2: Basically, but doing that requires a highly specialized detector. You
Speaker 2: can't just put a standard CCD chip from a digital
Speaker 2: point and shoot camera into space and hope to see infrared.
Speaker 3: No the thermal noise which is blind the sensor.
Speaker 2: And this brings up a really crucial question for me.
Speaker 2: A twenty cent meter telescope is still incredibly small, very small.
Speaker 2: We have ten meter telescope sitting on mountains right here
Speaker 2: on Earth, massive observatories. Why bother sending an eight inch
Speaker 2: mirror into orbit when we could just use a giant
Speaker 2: ground based observatory to look for these infrared transits?
Speaker 3: Because the Earth's atmosphere is an absolute nightmare for infrared astronomy.
Speaker 2: A nightmare.
Speaker 3: How well, First you have the turbulence of the atmosphere itself,
Speaker 3: which causes the light from the star to waver.
Speaker 2: And twinkle right the twinkling stars.
Speaker 3: That twinkling introduces an unacceptable level of noise into the
Speaker 3: photometric data. It ruins the precision. But the really insurmountable
Speaker 3: barrier is.
Speaker 2: Water vapor, water vapor like clouds.
Speaker 3: Even just the invisible moisture in the air. The water
Speaker 3: molecules in Earth's atmosphere act like a solid brick wall
Speaker 3: for many bands of infrared light. They physically absorb the
Speaker 3: incoming infrared radiation for it ever reaches the ground.
Speaker 2: Wow, So our atmosphere is effectively opaque to the very
Speaker 2: light po it needs to see.
Speaker 3: Exactly the problem. You could build a one hundred meter
Speaker 3: telescope on the ground, and it still wouldn't matter for
Speaker 3: certain infrared wavelengths because the signal simply doesn't reach the mirror.
Speaker 2: It's getting soaked up by the sky.
Speaker 3: Right, So, by placing a small, highly stabilized twenty centimeter
Speaker 3: telescope in the vacuum of space, far above all that water,
Speaker 3: vapor and atmospheric.
Speaker 2: Turbulence, it's just perfectly clear.
Speaker 3: Poet operates in pristine silence. It can gather uncorrupted photons
Speaker 3: with a precision that ground based observatories can literally only
Speaker 3: dream of.
Speaker 2: Okay, so that makes perfect sense. We have our perfect,
Speaker 2: highly tuned infrared camera in orbit. The next big hurdle
Speaker 2: is figuring out where exactly to point it.
Speaker 3: Yes, target selection is everything, because you can't just sweep
Speaker 3: the sky blindly with a tiny satellite and hope a
Speaker 3: transit happens to occur while you're looking.
Speaker 2: Space is too big.
Speaker 3: Way too big, and telescope time is expensive.
Speaker 2: You need a highly curated list, which brings us to
Speaker 2: the Peel input catalog.
Speaker 3: The creation of this catalog is an exercise in ruthless
Speaker 3: ruthless optimization. Howso, the initial sweep identified over seven thousand
Speaker 3: two hundred candidate ultra cool dwarfs.
Speaker 2: Okay, that's a lot of potential targets.
Speaker 3: It is, but like you said, telescope, time and space
Speaker 3: is a precious, finite resource. Poet's primary mission timeline.
Speaker 2: Is just a year, oh, just one year, one year, So.
Speaker 3: Pointing the satellite at a star that has a low
Speaker 3: probability of yielding a clean transit is a total waste
Speaker 3: of multimillion dollar hardware. They had to aggressively filter that
Speaker 3: list down to just over three thousand candidate.
Speaker 2: Okay, so how do they narrow it down? The first
Speaker 2: major filter was proximity, right.
Speaker 3: Right, proximity is huge.
Speaker 2: They restricted the final catalog to candidates located within one
Speaker 2: hundred parsecs from Earth, and just to bypass the astronomical
Speaker 2: jargon here, a parsec is about three point two six
Speaker 2: late years right, So one hundred par six is roughly
Speaker 2: three hundred and twenty six light years in galactic terms.
Speaker 2: This is basically our front porch.
Speaker 3: Oh entirely, the Milky Way is one hundred thousand light
Speaker 3: years across. We are exclusively looking at our immediate neighbors, So.
Speaker 2: Why restrict it so much?
Speaker 3: Why not look further it's dictated by the inverse square
Speaker 3: law of light. Even though POET is optimized for infrared,
Speaker 3: ultra cool dwarfs are inherently dim. They just don't put
Speaker 3: out a lot of energy, right. They're embers, and the
Speaker 3: intensity of light drops off exponentially as distance increases. If
Speaker 3: you select a target that's a thousand light years away,
Speaker 3: the satellite simply won't collect enough photons to achieve the
Speaker 3: signal to noise ratio required to detect a transit.
Speaker 2: It would just be too faint to measure a one
Speaker 2: percent drop exactly.
Speaker 3: By staying within one hundred parsex, the team guarantees a
Speaker 3: high enough photon flex to make the measurements statistically viable.
Speaker 2: Okay, so the distance filter makes perfect logical sense. But
Speaker 2: there's another parameter that you use that feels completely counterintuitive
Speaker 2: to me.
Speaker 3: The bright stars.
Speaker 2: Yes, the catalog specifically ext excluded binary star systems, which
Speaker 2: I totally understand, right.
Speaker 3: Two stars orbiting a common center of mass. Their overlapping
Speaker 3: light curves would make teasing out a planetary transit a
Speaker 3: mathematical nightmare.
Speaker 2: It would be a mess. But they also explicitly excluded
Speaker 2: extra bright stars, which if you are struggling to collect
Speaker 2: photons with a tiny twenty centimeter telescope. Why on earth
Speaker 2: would you deliberately exclude the brightest targets in your category.
Speaker 3: It really does seem backwards until you dive into how
Speaker 3: the detector actually works at a physical level.
Speaker 2: Okay, explain the detector to me.
Speaker 3: The sensors on a satellite are essentially grids of microscopic
Speaker 3: buckets called pixels, and they collect photons. Every time a
Speaker 3: photon hits a pixel, it generates an electron.
Speaker 2: Right basic digital photography exactly.
Speaker 3: But if you point the telescope at a star that
Speaker 3: is too bright, those microscopic buckets fill up with electrons
Speaker 3: far too quickly.
Speaker 2: They saturate. The bucket literally overflows, Yes.
Speaker 3: The technical term is blooming. The electrons physically spill over
Speaker 3: into adjacent pixels, completely corrupting the image.
Speaker 2: Oh so it ruins the data for the surrounding area too.
Speaker 3: Completely ruins it. But even before you reach full saturation,
Speaker 3: there's another problem called poisson.
Speaker 2: Noise woss on noise. What is that?
Speaker 3: It has to do with the fact that the arrival
Speaker 3: of photons from a star isn't perfectly steady. It's not
Speaker 3: a continuous, smooth stream. It follows a statistical distribution.
Speaker 2: Okay, so it fluctuates.
Speaker 3: Right, There's a natural, completely unavoidable variance in the number
Speaker 3: of photons hitting the detector from millisecond to millisecond For
Speaker 3: an extra bright star. The sheer volume of photons means
Speaker 3: that the absolute value of this statistical noise is huge.
Speaker 2: H So the noise floor naturally rises with the brightness.
Speaker 3: Yes, exactly, the tiny little dip caused by the planetary
Speaker 3: transit just gets swallowed whole by the massive, unavoidable statistical
Speaker 3: noise of that overwhelmingly bright star.
Speaker 2: Wow. It's like trying to hear a pin drop inside
Speaker 2: a heavy metal concert.
Speaker 3: Perfect analogy. It doesn't matter how good your microphone is.
Speaker 3: The background volume makes it impossible.
Speaker 2: So you need stars that aren't too dim but aren't
Speaker 2: too bright either.
Speaker 3: Right. By focusing on a Goldilock's level of brightness, stars
Speaker 3: that provide enough photons to measure, but not so many
Speaker 3: that the detector saturates or the statistical noise spikes po
Speaker 3: it maximizes its sensitivity.
Speaker 2: That is brilliant. Okay, So they run the numbers on
Speaker 2: this highly refined Goldilocks catalog and the computer models predict
Speaker 2: that pot can reliably detect Earth sized exoplanets, specifically worlds
Speaker 2: between one and two point five Earth radii.
Speaker 3: So true Earth sized worlds and super Earth.
Speaker 2: But the models also highlight the orbital periods. There are
Speaker 2: specifically targeting planets with orbital periods ranging from seven to
Speaker 2: fifty days, and.
Speaker 3: We really need to unpack the physical reality of a
Speaker 3: seven day orbital.
Speaker 2: Period because it sounds crazy. The orbital period is the
Speaker 2: length of a planet's year. Earth takes three hundred and
Speaker 2: sixty five days to complete a circuit around our Sun.
Speaker 2: If a planet is whipping around its host star in
Speaker 2: just seven days, its orbital radius has to be incredibly small.
Speaker 2: It is practically skimming the surface of the star.
Speaker 3: It's hugging it tight.
Speaker 2: Right. If you put Earth on a seven day orbit
Speaker 2: around our Sun, it wouldn't even be a planet anymore.
Speaker 2: It'd be a molten droplet of magma. The heat would
Speaker 2: strip the atmosphere away in a matter of hours.
Speaker 3: It would be totally annihilated, exactly.
Speaker 2: So this seems to contradict the entire goal of the mission.
Speaker 2: We are looking for another Earth, presumably a place that
Speaker 2: could harbor life. Why prioritize planets parked in an absolute inferno.
Speaker 3: Because around an ultra cool dwarf, a seven day orbit
Speaker 3: is not an inferno.
Speaker 2: Because the star is so cold.
Speaker 3: Exactly. It brings us directly into the concept of the
Speaker 3: habitable zone. The habitable zone, often called the Goldilocks zone,
Speaker 3: is the specific orbital band around a star where the
Speaker 3: surface temperature of a rocky planet is theoretically stable enough
Speaker 3: to maintain liquid water.
Speaker 2: And liquid water is the absolute indispensable solvent for all
Speaker 2: known biology.
Speaker 3: We haven't found a single living thing that doesn't need it.
Speaker 2: So the boundaries of that Goldilock zone are entirely dependent
Speaker 2: on the energy output of the host star.
Speaker 3: The campfire analogy works best here.
Speaker 2: I think, oh, I like that. Let's hear it.
Speaker 3: Our sun is a raging bonfire. If you want to
Speaker 3: not get burned, you have to stand quite a distance away.
Speaker 3: Earth sits comfortably in that outer band where it's just
Speaker 3: nice and warm, makes sense, But an ultracol dwarf is
Speaker 3: just a tiny smoldering ember. If you want to feel
Speaker 3: the warmth, if you want your water to remain liquid
Speaker 3: and not freeze solid, you have to huddle intimately close
Speaker 3: to the fire.
Speaker 2: So for a star that is ten percent the mass
Speaker 2: of our Sun and thousands of degrees cooler, the habitable
Speaker 2: zone just gets pulled in incredibly tight, very.
Speaker 3: Tight, so tight that a planet residing right in the
Speaker 3: middle of an ultra cool dwarf's habitable zone will complete
Speaker 3: its entire orbit in a matter of days or a
Speaker 3: few weeks.
Speaker 2: Okay, So this seven to fifty day parameter isn't just
Speaker 2: a convenient byproduct of the transit method.
Speaker 3: No, it is actively filtering for planets sitting right in
Speaker 3: the sweet spot for liquid water.
Speaker 2: Orbiting that close to a star, even a dim one
Speaker 2: introduces a massive physical complication. At a seven day orbit,
Speaker 2: the gravitational interaction between the star and the planet has
Speaker 2: to be immense.
Speaker 3: You're bringing up the elephant in the room.
Speaker 2: Tidal locking, Yes, tidal locking. Because the planet is so close,
Speaker 2: the gravitational pull of the star exerts an extreme tidal
Speaker 2: force on the planet's mass.
Speaker 3: Right it's pulling on the rock itself, and over millions
Speaker 3: of years, this tidal friction physically slows the planet's rotation down.
Speaker 3: It slows down until its rotational period perfectly matches its
Speaker 3: orbital period.
Speaker 2: This, like our Moon. The Moon is tidally locked to Earth,
Speaker 2: which is why we only ever see one side of it.
Speaker 3: It's exactly the same mechanism. An Earth sized planet in
Speaker 3: a seven day orbit around a brown dwarf will have
Speaker 3: one hemisphere permanently facing the star, bathed in eternal daylight.
Speaker 2: And the other hemisphere is permanently facing the deep frieze
Speaker 2: of space, locked in eternal night.
Speaker 3: Right.
Speaker 2: I mean that sounds like a catastrophic environment for life.
Speaker 2: One side is a boiling desert and the other side
Speaker 2: is a frozen wasteland of solid carbon dioxide. How does
Speaker 2: a planet like that support liquid water.
Speaker 3: It's a great question, and it really comes down to
Speaker 3: atmospheric dynamics. Early models actually assume what you just said,
Speaker 3: that tidally locked planets would boil off their atmospheres on
Speaker 3: the day side, which would then just freeze out and
Speaker 3: collapse onto the night side.
Speaker 2: Leaving a completely barren rock exactly.
Speaker 3: But advanced climate modeling over the last few years suggests
Speaker 3: a much more robust mechanism. Really, how so, if the
Speaker 3: planet has a sufficiently thick atmosphere, that extreme temperature difference
Speaker 3: actually drives massive planet wide winds.
Speaker 2: Oh a global circulation system redistributing the heat.
Speaker 3: Yes, the incredibly hot air on the day side expands
Speaker 3: and rises rapidly, and then it rushes across the terminator line,
Speaker 3: which is the permanent twilight zone dividing day and.
Speaker 2: Night, and it carries that heat to the dark hemisphere.
Speaker 3: Right, this constant, violent convection could stabilize the entire climate.
Speaker 3: It would prevent the oceans on the day side from
Speaker 3: boiling away and keep the atmosphere on the night side
Speaker 3: from freezing solid.
Speaker 2: That is so wild, So life might actually thrive right
Speaker 2: in the middle in that terminator.
Speaker 3: Zone, exactly perpetually bathed in the dim red light of
Speaker 3: a sun that literally never sets, anchored by these relentless
Speaker 3: global winds.
Speaker 2: The environment would be profoundly alien, but physically mathematically capable
Speaker 2: of supporting biology.
Speaker 3: That's the current consensus.
Speaker 2: Yet, and this really underscores the ultimate role of the
Speaker 2: Poet mission, because Poet is not going to definitively find
Speaker 2: alien life on its own, right.
Speaker 3: Oh No, A twenty centimeter microsatellite doesn't have the resolving
Speaker 3: power to image alien forests or detect biological gases.
Speaker 2: Right Poet illit is essentially the ultimate cosmic Scout a
Speaker 2: scout Yes. Its mission is to survey the neighborhood, identify
Speaker 2: the handful of rocky planets residing in the habitable zones
Speaker 2: of these dim stars, and hand off their precise coordinates.
Speaker 3: It acts as the vanguard for a monumental cosmic relay race.
Speaker 3: Pewat runs the grueling first leg. It stares at those
Speaker 3: three thousand stars, watches all the static, and finally flags
Speaker 3: a confirmed target and then what. Once Pewitt determines the
Speaker 3: planet's exact size and the precise timing of its transit,
Speaker 3: it passes the baton to the heavy hitters of modern astronomy.
Speaker 2: Of billion dollar observatories.
Speaker 3: Exactly observatories like the James Webb Space Telescope or the
Speaker 3: upcoming Habitable World's Observatory.
Speaker 2: Because you can't just point a ten billion dollar machine
Speaker 2: like WEB at a random star and hope you get lucky.
Speaker 3: Never, telescope time is fiercely, fiercely competed for by scientists globally.
Speaker 3: It requires guaranteed high priority targets.
Speaker 2: WEB needs know exactly when and where to look.
Speaker 3: Down to the minute and when WEB looks at a
Speaker 3: pwet discovered planet during a transit it executes an incredible
Speaker 3: technique called transmission spectroscopy.
Speaker 2: Okay, let's break down the mechanics of transmissions tectroscopy, because
Speaker 2: this is basically how we sniff an alien atmosphere without
Speaker 2: ever leaving Earth.
Speaker 3: Right, That's exact eactly what it is. When the rocky
Speaker 3: body of the planet passes in front of the star,
Speaker 3: it blocks light like we discussed, But a rocky planet
Speaker 3: isn't just a solid sphere. It has a thin halo
Speaker 3: of gas surrounding it its atmosphere. As the starlight streams
Speaker 3: toward Earth, a microscopic fraction of it actually grazes the
Speaker 3: very edge of the planet and passes directly through that atmosphere.
Speaker 2: So the starlight is essentially being filtered through the alien.
Speaker 3: Air beautifully said. Yes, and different chemical molecules absorb different
Speaker 3: very specific wavelengths of light. Water vapor absorbs one specific
Speaker 3: set of frequencies, carbon dioxide absorbs another, methane absorbs yet another.
Speaker 2: It's a chemical fingerprint exactly.
Speaker 3: So when web captures that filtered starlight, its spectrograph acts
Speaker 3: like a highly advanced prism. It breaks the light apart
Speaker 3: into its constituent colors, and the scientists They just look for.
Speaker 2: The gaps, the missing wavelengths.
Speaker 3: Right. If a specific frequency of infrared light is completely
Speaker 3: missing the spectrum, you know exactly which molecule in the
Speaker 3: planet's atmosphere absorbed it because it acts like a barcode,
Speaker 3: a perfect chemical barcode. You have effectively analyzed the chemical
Speaker 3: composition of an atmosphere located hundreds of light years away.
Speaker 2: And the ultimate prize in reading that barcode is finding
Speaker 2: biosignature gases.
Speaker 3: That is the holy grail.
Speaker 2: Yes, we are looking for an atmosphere that is completely
Speaker 2: out of chemical equilibrium, right, because if you just leave
Speaker 2: a bunch of gases alone, geology and solar radiation will
Speaker 2: eventually cause them to react and settle into a stable
Speaker 2: dead state.
Speaker 3: Exactly. Look at Mars. Mars has an atmosphere in perfect equilibrium.
Speaker 3: It's mostly just carbon dioxide. It's totally geologically dead.
Speaker 2: But Earth's atmosphere is wildly.
Speaker 3: Unstable, very unstable. We have high concentrations of oxygen, which
Speaker 3: is incredibly reactive. Oxygen really wants to bond with everything
Speaker 3: and pull itself out of the atmosphere.
Speaker 2: But rust iron, it burns wood, It doesn't want to
Speaker 2: just float there.
Speaker 3: Right, And we also have methane, which reacts incredibly quickly
Speaker 3: with oxygen to form water and carbon dioxide. If you
Speaker 3: put methane and oxygen together, they naturally destroy each other rapidly.
Speaker 2: So if a telescope detects both oxygen and methane in
Speaker 2: high concentrations on the same.
Speaker 3: Planet, then something incredibly powerful has to be continuously pumping
Speaker 3: vast quantities of those gases into the air to replenish them,
Speaker 3: Otherwise they would just neutralize each other.
Speaker 2: Geological processes like volcanoes can produce some methane, right, and
Speaker 2: ultraviolet light breaking down water can produce a little bit
Speaker 2: of oxygen.
Speaker 3: Sure, abiotic processes can produce price amounts, but finding them
Speaker 3: in massive concurrent abundance that is exceptionally difficult to explain
Speaker 3: via purely geological mechanisms.
Speaker 2: So what's the most logical explanation.
Speaker 3: The most logical explanation for a planetary atmosphere held perpetually
Speaker 3: out of chemical equilibrium like that is a global biosphere.
Speaker 2: Life plants exhaling oxygen, and microbes producing massive amounts of.
Speaker 3: Methane exactly, And this brings it all back to why
Speaker 3: the precision of PO is just so critic Web's ability
Speaker 3: to analyze an atmosphere is entirely dependent on the quality
Speaker 3: of the light passing through it. By targeting ultra cool dwarfs,
Speaker 3: the planet's atmosphere blocks a proportionally larger amount of the
Speaker 3: star's total light. The transmission spectrum is thicker, it's clearer,
Speaker 3: and it's so much easier for WEB to read.
Speaker 2: It is such a beautifully synergistic approach. Canada provides this agile,
Speaker 2: relatively inexpensive microsatellite to do all the heavy lifting of discovery.
Speaker 2: It filters out all the noise of the cosmos, just
Speaker 2: defined the perfect geometric setups, and.
Speaker 3: Then the massive international mega observatories step in to read
Speaker 3: the chemical barcodes. It really is an extraordinary testament to
Speaker 3: how collaborative and highly optimize the search for extraterrestrial life
Speaker 3: has become.
Speaker 2: When you look at the entirety of this endeavor, it
Speaker 2: represents a really remarkable evolution in scientific thinking. We started
Speaker 2: by basically just staring at stars that looked like our own,
Speaker 2: using instruments that were only really capable of finding bloated
Speaker 2: gas giants.
Speaker 3: We were looking for our twin with the wrong glasses
Speaker 3: on right.
Speaker 2: We confirmed thousands of worlds that couldn't possibly support life,
Speaker 2: while the rocky, potentially habitable planets remain totally hidden in
Speaker 2: the glare. But instead of just hitting our heads against
Speaker 2: the wall, we change the parameters.
Speaker 3: The limitations of our tools forced a complete shift in perspective.
Speaker 3: If the sun like stars are too bright, well look
Speaker 3: at the dim ones right. If the habitable zone of
Speaker 3: a red dwarf is incredibly tight, use that to your advantage,
Speaker 3: because those tight, fast orbits mean more transits and faster confirmation.
Speaker 2: The physics that initially seem like a massive barrier, you know,
Speaker 2: the tiny size of the stars, the tidal locking of
Speaker 2: the planets, They are actively being weaponized to make detection possible.
Speaker 3: It is the ultimate expression of scientific pragmatism.
Speaker 2: The upcoming launch of Payat in twenty twenty nine isn't
Speaker 2: just about putting another mirror in space. It is about
Speaker 2: deploying a highly targeted strategy to sift through the cosmic
Speaker 2: noise of our local neighborhood, to ignore the bright, chaotic
Speaker 2: suns in favor of the quiet red embers.
Speaker 3: It'll map the orbital periods, measure the radii, and basically
Speaker 3: hand the absolute most promising seven day year super Earth's
Speaker 3: directly over to the heavy machinery to search for the
Speaker 3: breath of life.
Speaker 2: The ingenuity of finding a way to measure a fractional
Speaker 2: dip in infrared starlight from a satellite the size of
Speaker 2: a washing machine, it just cannot be overstated.
Speaker 3: It's amazing. It brings the loftiest, most philosophical question humanity
Speaker 3: has ever asked, Are we alone down to a literal
Speaker 3: matter of photon collection and noise reduction?
Speaker 2: And as we wait for this mission to launch, it
Speaker 2: leaves us with a rather profound philosophical pivot to consider.
Speaker 2: When we look up at the sky, we instinctively view
Speaker 2: Earth as the standard, the baseline.
Speaker 3: Of course we do. It's all we know, right.
Speaker 2: We have a massive, fiercely hot yellow Sun, we have
Speaker 2: a nice, leisurely three hundred and sixty five day orbit,
Speaker 2: we have regular days and nights, and we just assume
Speaker 2: this is the ideal universal template for a thriving biosphere.
Speaker 3: But the sheer math of the galaxy tells a very
Speaker 3: different story.
Speaker 2: Because ultra cool dwarfs, red dwarfs, and brown dwarfs make
Speaker 2: up the overwhelming majority of stars in the Milky.
Speaker 3: Way, Yellow dwarfs like our sun are actually in the
Speaker 3: tiny minority.
Speaker 2: So imagine the scenario a decade from now. What if
Speaker 2: Webb points its massive mirrors at one of pode It's
Speaker 2: prime targets. What if it analyzes the atmosphere of a
Speaker 2: super Earth tightly orbiting a dim red failed star.
Speaker 3: A planet locked in eternal twilight with a year that
Speaker 3: lasts only six days exactly?
Speaker 2: And what if it finds the undeniable chemical fingerprint of
Speaker 2: a robust, churning global biosphere.
Speaker 3: It demands a total reevaluation of our place in the
Speaker 3: cosmic hierarchy.
Speaker 2: It really would. It would mean our blazing sun and
Speaker 2: our long varied seasons aren't the standard template at all.
Speaker 2: If life can take root and thrive in the fierce,
Speaker 2: tidally lock winds of a red dwarf system, it forces
Speaker 2: us to ask an incredibly humbling question.
Speaker 3: What if we are the cosmic oddballs?
Speaker 2: Exactly? What if the true bustling metropolises of the universe
Speaker 2: aren't bathed in bright yellow light like our own, but
Speaker 2: are hidden away in the dim red glow of the
Speaker 2: galaxy's smallest inhabitants. The so called failed stars might just
Speaker 2: turn out to be the most successful engines of life
Speaker 2: in the universe, and we are just the outlier, finally
Speaker 2: learning how to look in the dark.