Welcome to Bedtime Astronomy. Explore the wonders of the cosmos with our soothing Bedtime Astronomie podcast. Each episode offers a gentle journey through the stars, planets, and beyond, perfect for unwinding after a long day. Let's travel through the mysteries of the universe as you drift off into a peaceful slumber under the night sky.
I want you to close your eyes for a second. We're going to do something a little dark to start things off today.
Oh I'm intrigued.
I want you to imagine the absolute worst case scenario. And I'm not talking about a stock market crash or a hurricane, or even a zombie apocalypse. I'm talking about the ultimate cosmic end game, the big one, the death of a solar system.
It is a scale of destruction that is genuinely hard for the human mind to process. I mean, we are talking about physics on a scale that makes our most powerful nuclear weapons look like tiny firecrackers popping in the distance exactly.
And I think when most people picture this the end of the world or the end of a star system, they think of science chittus.
A death star.
You think of the death star, right it's a giant laser beam, a sudden green flash and explosion and boom, the planet has gone instant darkness. But the reality, the actual science of it, is actually much slower and much more insidious, and honestly, it is a lot scarier.
It is not an explosion.
It's a suffocation.
That is a very very apt way to put it. It's the slow, inevitable swelling of a star, the transition to the red giant phase.
The red giant just the name sounds menacing. Picture of star are maybe running out of fuel. It gets angry, It starts expanding outward like a balloon being overinflated. It swallows everything in its path. Mercury gone, Venus toast toast. Earth will get to Earth later. And it's not a pretty picture. But for a long time, the assumption in astronomy was that this is basically a death sentence for the entire neighborhood. If your star goes red giant, it's game over.
That has been the prevailing wisdom for decades. When a star sheds its outer layers and swells up, the gravitational and thermal forces are so extreme that we generally assume planetary systems are wiped clean.
The slate is wipe blank exactly.
The star expands, consumes the inner planets, destabilizes the outer ones, and leaves nothing but dust.
But and this is why we are here today. There's a twist, you plot twist in the story of stellar death. H It turns out not everyone dies. There are survivors, party survivors, and that is the mystery we are unpacking today. How do you survive being swallowed or scorched by your own son? And more importantly, who are these survivors? Because we have some brand new informations literally hot off the breast, that changes how we look at this.
It really is brand new. I mean we are looking into data that came out essentially yesterday, February fourth, twenty twenty six.
It doesn't get fresher than that. Yeah, So what are we looking at? What's the source?
This is a new study published in Astronomy and Astrophysics and it's currently making waves on the ARCSIV server. The title is predicted incidents of Jupiter like planets around white dwarfs.
Predicted incidents. It's very polite.
Academic titles always hide at the drama, don't they. But the lead author is alex Mars Soriano from the DEPARTMENTA of Phisica at the University DoD Technica Federico Santa Maria in Valpariso, Chile, Okay. And what they have done is fascinating. They haven't just looked for these planets with a telescope, They've built a comprehensive simulation of the Milky Way to predict them.
So our mission today is to look at this census of the survivors. We want to know, out of all the planets that face this fiery apocalypse, how many actually make it through to the other side.
And we aren't just looking at pretty pictures of space here, we are digging into the physics. Yeah, we need to figure out exactly how rare these survivor planets are. Are they one in a million, one in ten?
Right? And why does one planet survive while its neighbor gets completely vaporized?
And here is the So what for you listening right now? This isn't just about some distant star light years away. This is a preview.
It's a trailer.
It's a trailer for the future of our own Solar system. We are basically looking at the fate of Jupiter and Saturn.
That is exactly right. By studying these distant systems, we are essentially looking into a crystal ball for our own neighborhood. We're seeing our own future played out on a galactic stage.
Yeah, future, that's about what five six billion years away, But still it's written in the stars.
So let's unpack this. Before we get to the survivors. We have to understand the killer. We need to talk about the mechanism of destruction. Why is survival so incredibly hard?
To understand the destruction, you have to understand the life cycle of a star. Most stars, like our Sun, spend the vast majority of their lives in what we call the main sequence.
That's the happy, stable time, the prime of life.
Correct, it's burning hydro into helium in its core. It's stable. Gravity is pulling in trying to crush the star, but the energy from fusion is pushing out, and everything is in a perfect hydrostatic balance, a standoff. It's a standoff between two tightened forces, and as long as there is fuel, the standoff holds. But eventually the hydrogen runs.
Out, the fuel tank gets empty, and when the gas tank is empty in a car, the car stops.
Right in a car, Yes, in a star, it's the opposite. When the fuel runs out in the core, the engine goes haywire. Core starts to collapse because there's no outward pressure to hold it up to more. But as the core collapses, it gets hotter, much much hotter. This new intense heat pushes the outer layers of the star away, so.
The outer parts stop listening to gravity.
They stop listening to gravity, they start to expand drastically. The star transitions from a main sequence star into a red giant.
I always like the analogy of a marshmallow in a microwave.
That is surprisingly accurate.
Go on, you know what I mean. You put a regular hence marshmallow and you hit start. It heats up from the inside and it just starts expanding. It gets huge, it gets fluffy, It takes up the whole microwave.
But unlike a marshmallow, which is delicious.
A red giant is incredibly dangerous. If you are orbiting nearby.
It is lethal. The radius of the star can increase by a factor of one hundred or even more. Our Sun will swell up to roughly the orbit of Earth. It physically takes up more space and This leads to the three ways a planet can die, the three.
Methods of execution. Let's go through them, because this really sets the stakes. It's not just one thing that kills you. It's a triple threat.
The first and most obvious is engulfment, which is just what it sounds like. It's exactly what it sounds like. The star physically expands past the planet's orbit. The planet literally flies inside the star's atmosphere, and.
Space is a vacuum, so there's usually no friction. But inside a star, that's a different story.
It's a very different story. It's gas. It's thick. The friction from the gas the drag. It slows the planet down, it loses orbital speed, spirals into the core, and is obliterated. Wow, this is the likely fate of mercury and venus in our own system. They will simply be swallowed whole.
And possibly Earth. But we'll pinachaotic maybe on that for now. So that's engulfment being eaten alive. What's the second way to die?
Tidal forces? This one is a bit more subtle, but just as.
Destructive, like the tides of the ocean.
Same principle, but on a mind boggling scale. As the star loses mass because it's puffing out these layers into space, it's gravity changes. But also because the star is so huge and you're so close, the gravitational pull on the side of the planet facing the star is much stronger than.
The pole on the far side, so it gets stretched.
Ripped apart. Really, we call this spaghettification when we talk about black holes, but a similar thing happens here. These intense gravitational poles can physically disassemble a planet before it even gets engulfed.
It just crumbles under the stress.
The planet's own gravity isn't strong enough to hold it together against the pull of the star. It's like pulling a piece of bread apart.
Okay, so you can be eaten or you can be ripped to shreds. Not great options.
And the third vaporization, the transition from a main sequence star to a red giant involves intense heat spikes. The luminosity, the brightness of the star skyrockets, so it's not just bigger, it's also hotter incredibly, so the radiation can be so intense that it boils the planet away. It strips the atmosphere, then boils the oceans and melts the rock. It's like holding a candle to an ice cube, but the candle is a star and the ice cube is a planet.
So it's a gauntlet you have to dodge being eaten, being torn apart, and being.
Boiled precisely, And if a planet manages to survive all of that, if it survives the red giant phase, the star eventually sheds all those outer pucky layers.
Where do they go?
They drift away into space, creating what we call a planetary nebula, which ironically is often beautiful to look at.
I've seen pictures. They're gorgeous, but it's really a stellar graveyard.
It is, and what is left behind is the core, a dense, hot, tiny remnant called.
A white dwarf, the corpse of the star.
A very hot corpse, but yes, about the size of Earth, but with the mass of the Sun, incredibly dense. A teaspoon of it would weigh tons.
So if we look up at the sky with our telescopes and we see a white dwarf and we see a planet orbiting it, that planet is a veteran.
It is a survivor of a stellar war. It witnessed the expansion. It survived the tides, it endured the heat, and it is still standing. It has a story to tell.
That makes them incredibly special. It means they have a story to tell. But for a long time, we didn't know if any planets actually could survive this. It was all theoretical math on a chalkboard exactly.
We had the models, but we didn't have the proof, so we were just guessing. We were guessing until about fifteen years ago. We hoped they existed, but we hadn't seen one. We weren't sure it was even possible.
But then we found evidence, and this takes us to the second part of our journey. Today we know they exist. This isn't just math anymore.
No, we have direct observations. The first major clue came back in twenty eleven.
Take us back to twenty eleven. What did they find?
Astronomers discovered an exoplanet orbiting a white dwarf. It was massive, about eight times the mass of Jupiter.
That is a beast of a planet that's bordering on a brown dwarf. Isn't it one of those failed stars?
It's getting there but still classified as a planet. But the key detail wasn't its size, it was its location. It was orbiting at a distance of about twenty five hundred astronomical units AU.
Okay, let's put that in respective for everyone. One AU is the distance from the Earth to the Sun. That's our yardstick. Jupiter is about five AU out right.
And Pluto, which we all think of as being way out there, is about forty AU on average.
And the voyager probes the furthest things humans have ever sent are only about one hundred and fifty to one hundred and sixty AU out right now, and they've been traveling for decades.
So this thing at twenty five hundred AU was way way out there.
That is lonely. That is deep deep space, that is practically in the interstellar void.
It is incredibly far, but that distance is exactly why it survived. We call this survival tactic the distant observer self explanatory. It was simply too far away to be touched by the Red Giant's expansion. The star swelled up, but the planet was sitting way back in the cheap seats watching the fireworks, completely safe.
So the strategy there is simple avoidance. Just be really really far away.
Exactly. It's the safest bet. If you aren't near the explosion, you don't get hurt. Problem solved.
But then in twenty twenty we got a second clue that really complicated the picture.
The plot thickens because nature is never that simple.
Never what happened in twenty twenty.
Astronomers found another Jupiter sized gas giant around a white dwarf. But this one was orbiting very close to the star.
How close are we talking?
Close enough that it completes an orbit in just a few days, not years. It was hugging the star well well within where Mercury's orbit would be in our Solar system.
Wait, hang on, if it's that close, it should have been eaten. We just established that when the star was a red giant, it would have expanded way past that orbit, way past it should be inside the star's stomach, effectively exactly. That is the puzzle. It could not have survived the red giant phase at its current distance. It would have been engulfed and destroyed instantly, no question. So how is it there? Is it a ghost planet? Did it form afterwards? Like a phoenix rising from the ashes?
Unlikely to form afterwards? There isn't usually enough material left in the disk around a white dwarf to build a giant.
Planet from scratch, it was the theory.
The leading theory is that this planet is the migrator. It didn't start there. It survived the red giant phase by being further out, maybe in that safe zone we talked about beyond a few au Okay.
So as a distant observer at first.
Yes, But then after the star shrank down into a white dwarf and things calmed down, something caused the planet to spiral inward.
So it moved into the empty house after the fire was put out.
That's a great way to put it. It survived the danger zone, then migrated in later. Usually this happens because of scattering. Maybe another massive planet in the system gave it a gravitational kick, or the disc of debris left over from the star's death dragged it in.
So we have two pathways to survival. Pathway one the distant observer stay far away and don't move. Pathway two the migrator stay far away during the danger, then move in close when it's safe.
Those seem to be the two main options. If you stay close and don't move, you die.
Simple rules for a complicated universe. But here's the problem, and this leads us right into the new research from Max Soriano. We found these two examples, right, A couple others maybe, but we haven't found many.
That is the issue. We have found thousands of exoplanets around normal stars, thousands, we find them everywhere we look. But planets around white dwarfs we have a literal handful.
So the question is are they missing because they are rare, or are they missing because we just aren't good at seeing them.
This is the classic servational bias problem in astronomy. It's a huge question.
Maybe they're there, but we just can't spot them.
It's possible white dorks are dim. Planets are dim. Maybe the glare from the white dwarf, even though it's faint, hides them. Maybe we just haven't looked at enough of them for long enough. It's like looking for a needle in a haystack, but we aren't sure if we're even holding a magnet.
And this is where Max Soriano and the team from Chili come in. They decided to stop guessing and start simulating.
Right. Instead of just relying on our limited telescope data, they used stellar evolution codes. They essentially built a physics engine of the Milky Way.
I love when scientists do this. We can't find it, so let's build a universe where we can calculate it. It's like playing some city, but with solar systems.
It's an incredibly powerful tool. They factored in everything mass loss from the star, how gravity changes, the tidal forces, which we'll get to, the metallic makeup of stars. They ran the numbers to predict how many of these survivors should exist.
So they're not observing, therefore casting exactly.
They simulated the entire life cycle from birth to death for millions of scenarios to see what the end result should be, and they.
Came back with a number, a specific percentage of white dwarfs that should have a Jupiter like survivor orbiting them.
They did, and that number is less than three percent.
Wow, less than three percent. Yes, that means for every one hundred dead stars you look at, ninety seven of them are alone or at least they don't have a gas giant survivor.
It is a massacre out there. The vast, vast majority of planets do not make it.
That feels incredibly low. I mean, we look at our Solar System. We see Jupiter and Saturna. They seem so big and permanent. We think of them as the kings of the Solar System. We assume they are invincible. But you're saying, in the grand scheme of stellar evolution, keeping a planet like that is a rarity.
It is. The transition to a white dwarf is a chaotic, violent event. It cleans house. Now there is a small caveat the researchers point out, which is important. If we look at what they call the local age metallicity relation, basically stars that are similar to our Sun and in our local neighborhood of the galaxy, that number might creep up to roughly eight percent.
Okay, eight percent is better than three percent, but it's still single digits. It's still a tiny minority.
Absolutely. It implies that a white dwarf with a planet is the exception, not the rule. The default state for a dead star is loneliness.
And another thing that study noted, ninety five percent of these survivors are gas giants like Jupiter, not brown dwarfs.
That's an important distinction. Brown dwarfs are these failed stars. They are heavier than planets anywhere from thirteen to eighty times the mass of Jupiter, but not heavy enough to ignite fusion in their cores.
You would think being heavier and tougher they would survive better.
Yeah, logic would suggest the biggest kid on the playground doesn't get pushed around. If you're heavier, you should be harder to push into the star. Right, more inertia, you'd think, But the simulation shows that planets seem to survive better than brown dwarfs in this specific context. It's a nuanced interplay of a few things.
Like what well.
First, Brown corps are rare to begin with compared to gas giants, but more importantly, they interact with tides differently. They raise much stronger tides on the star because they.
Are so massive ah, and stronger tides create more.
Drag exactly, more drag which pulls them in faster. So being big can actually be a disadvantage here. You're too good at slowing yourself down and spiraling to your doom.
So if you want to survive the apocalypse, be a gas giant, don't be a brown dwarf, and definitely don't be a rocky planet like Earth.
Correct, Rocky planets are usually too close, they get swallowed. Being small and close is a death sentence.
Okay, so we know it's rare, we know it's dangerous. But let's dig into the survivor's handbook. Because even though only three percent make it, some do make it. Who are they? What makes them special? The paper breaks this down into specific factors they did.
They identified several key factors. Think of this as the checklist for survival. If you are a planet and you want to live, you need to check these boxes.
Factor're number one, the parent stars mass.
This is crucial. It turns out there's a Goldilock zone for the star itself. Not too hot, not too cold, not too big, not too small.
Okay.
Survival peaks when the resulting white dwarf ends up being between point five to three and point sixty six solar masses.
Okay, those are numbers. Translate that. What does that mean for the star before it died, when it was in its prime.
It corresponds to a progenitor, the original star having a mass of about one to three times the mass of our sun.
So you don't want a star that was too huge to begin with, right.
If the star is really massive, say eight or ten solar masses. It doesn't go out with a whimper. It goes out with a bang.
It goes supernova.
Yeah, and nobody survives as supernova nearby. That's just a bomb. It sterilizes the entire system.
Right.
But if the star is too small, like a red dwarf, it takes trillions of years to evolve. The universe isn't old enough for those to have turned into white dwarfs yet. So you need a star like the Sun or a bit bigger. That is the sweet spot for creating a white that might still have a planet. You need a star that lives a normal life span and dies a relatively gentle death.
Okay, so fac to one pick a medium sized star like ours, good start for us. Factor two the age of the system.
This was interesting. They found that younger systems, those between one and six billion years old, have higher survival rates. They are above that three percent baseline.
Wait, how can a young system have a dead star? That sounds contradictory. If it's young, shouldn't the star still be burning?
Young is relative in astronomy. A more massive star, say three solar masses, burns through its fuel much faster. It guzzles gas.
It lives fast and dies young exactly.
So you can have a system that is only two billion years old. But the star was big, so it burned through its fuel and a flash went through its red giant phase, died and became a white dwarf.
I see. So the system itself is young, even if its star is already dead.
Correct. And the study suggests that in these younger old systems more planets survive.
Why why does age hurt survival?
Well, the paper doesn't say for certain, but we can speculate maybe in much older systems ten twelve billion years old, there's just been more time for things to go wrong. Entropy, chaos, orbits destabilize over eons, Other stars pass by in the galaxy, and their gravity can nudge things around. The longer you hang around, the more likely you are to get kicked out of the system or crash into something else. It's dynamic instability.
Given enough time, gravity finds a way to ruin your day.
That's a good way of putting it.
So speed matters. Get the apocalypse over with quickly if you want to keep your planets.
In a manner of speaking, Yes.
All right. Factor three. This one seems obvious, but we need the numbers orbital separation the safe zone.
The data is very clear here. Surviving companions are usually found between three and twenty four AU.
Let's context that again, Jupiter is at five AU.
So Jupiter is right at the inner edge of this survival belt.
That makes me nervous for Jupiter, it's barely safe. It's standing right next to the fire exit.
It is on the edge. But three AU seems to be the cutoff. Anything closer than three AU usually gets swallowed by the red giant expansion.
And what about the outer edge twenty four AU. What happens beyond that?
Well, anything further out than twenty four AU is safer from the expansion for sure, but it might be less common just due to how planets form in the first place. You don't get as many giant planets forming way way out there in the protoplanetary disk. The gas and dust are too thin to clump together efficiently.
So the survival belt is three to twenty four AU. If you are in there, you have a fighting chance.
Correct, it's the sweet spot.
And finally, fact four. This one sounded like a heavy metal band. Metallicity.
Ah Yes, metallicity in astronomy, we have a very funny periodic table. It confuses the chemists to no end. Also, to an astronomer, there is hydrogen, there is helium, and everything else is a metal.
Carbon, metal, oxygen, metal, nitrogen, iron, all metals.
So when we talk talk about a star with high metallicity, we mean a star that has a lot of heavier elements in it, elements that aren't the primordial hydrogen or helium from the Big Bang.
And why does that help a planet survive.
It's not so much that it helps them survive the fire. It helps them exists in the first place. High metallicity stars are more likely to form planets, especially giant ones.
It's a numbers game exactly.
You need the raw materials, the dust, the rock, the ice to build a gas giant core. If a star is rich in metals, it has more building blocks available in its initial discs.
It's like trying to build a lego castle. If you have three buckets of bricks, you can build a bigger, better castle than if you only have three bricks.
Perfect analogy. If a star is rich in metals, it builds more planets and bigger planets. So if you start with more planets, statistically you end up with more survivors.
The quote in the paper was something like, progenitors with higher metallicities simply form more planets.
Simple logic. More lottery tickets means a higher chance of winning.
So to recap the survivor's handbook, pick a sun likes don't be too old as a system, orbit between three and twenty four AU, and make sure your star is made of heavy stuff.
That is your best bet for making it through. But even then, there is an invisible killer we haven't discussed yet, a variable that could ruin everything.
The invisible killer. This sounds ominous, it is.
We mention it briefly in the death list, but we need to go deeper. We need to talk about tides.
This was a big part of the new paper, right, the physics of tides. Now, when I think of tides, I think of the beach, the moon pulls the water, high tide, low tide. It's peaceful.
That is the basic concept gravity from one object stretching another. But now scale it up to a star that is swelling to the size of Earth's orbit. Okay, not peaceful, not peaceful at all. As the star swells, it becomes fluffy. It's not a dense ball anymore. It's a diffuse, turbulent cloud of hot gas what we call the convective envelope marshmallow.
Again.
Yes, Now, imagine a planet orbiting through the outer edges of that fluff. We're just near it. The planet raises tides on the star. It gravitationally pulls the gas toward it, and the star raises tides on the planet.
It's a gravitational tuggle war.
It is. But here is the catch, tidal lag. The star is spinning and the planet is orbiting. They aren't perfectly syncd The bulge of gas that the planet pulls up it doesn't point directly at the planet because of the star's rotation. It lags behind or pulls ahead.
Okay, so they are at a sink. What does that do?
And that misalignment creates torque, It creates friction, It creates.
Drag drag like air resistance.
It's a very similar concept. Think of it like this. If the planet is orbiting through empty space, it glides effortlessly forever. But if the star swells up and the planet starts interacting with those powerful tidal forces, it's like the planet is suddenly wading through molasses that slows it down, and in orbital mechanics, if you slow down, you drop, your orbit decays, you spiral.
Inward toward the center of the star, toward destruction. So the tides act like a break, dragging the planet to its two exactly.
But here is the controversy in the paper, and it's a huge deal. The researchers had to choose between two different mathematical formulas for tides. Because we don't know exactly how thick or sticky that interaction is.
You can't test it.
We don't have a red giant nearby to test it on. So it's a big debate. In astrophysics. There are weak tides based on a model by a. Villaver and Lvio from two thousand and nine, and there are strong tides suggested by Ratio and colleagues back in nineteen ninety six.
What's the difference in the outcome?
It's enormous. Imagine the difference between wading through water versus wading through quicksand that is the difference between weak and strong tides.
So if the tides are weak, the planet.
Experiences less drag, it's more likely to stay in its orbit. The survival rate effectively doubles in.
Their simulation, doubles just from that one variable.
Yes, and if the tides are strong.
Then planet gets dragged in.
The drag is immense. The planet gets pulled in and destroyed much much more easily. The survival rate plummets.
So the fate of these planets literally hangs on a variable in a math equation that we aren't one hundred percent sure about.
Yet it does. The paper has this fascinating graph. They call it the island of probability in the strong tide scenario. The graph shows just this tiny, tiny island of mass and distance where a planet can live. Everywhere else is a sea of death.
And if you turn up the tides even a little bit more than that.
The island sinks. The survival rate drops to almost zero.
That is terrifyingly fragile. It means survival is on a razor's edge.
It highlights just how chaotic this transition is. It's not a gentle process. It is a violent, turbulent restructuring of gravity and matter. One small change in the physics can be the difference between life and death for an entire world.
So we have the simulation saying survival is rare, less than three percent. But let's go back to the reality check. We have telescopes, we have the James Web, we have giant ground based observatories. Why aren't we seeing more of these survivors?
The paper addresses this directly. They ask is this a detection problem or an existence problem?
Meaning are they there and we just can't see them, or are they just not there in the first place?
Right? Direct imaging Taking a picture of a planet is incredibly hard. It depends on contrast. You need a bright planet and a dim star, and.
White dwarfs change over time, don't they They do.
They're born incredibly hot, glowing white or blue, but they're not generating new energy. They're just cooling off. A young white dwarf is relatively bright and hot. An old one is cold and dim.
And the planet cools down too.
I assume exactly, it's not getting much energy from its dead stars. If you have a cold, faint planet orbiting a cold faint star, it's like trying to spot a piece of coal in a dark cellar from a mile away. Impossible, very very difficult. So the older the system, the harder it is to see a surviving planet.
So are we missing them?
Is that the answer, the conclusion in the paper is no, or at least not entirely. They argue that even when you account for how hard it is to see them, the number are still too low. Our current surveys should have found more by now if they were common.
So the scarcity is real. The simulation is likely correct.
Yes, the low number of detections isn't just because the eyes are bad. It reflects reality. They really are that rare. Most planets simply die.
That is a sobering thought.
It is It validates the simulation. The universe is a graveyard of planetary systems.
Well on that cheerful note. Yeah, let's bring this home, literally home to our Solar system, because we started this by saying this is a trailer for our future.
Yes, let's apply these findings to us. Let's run the diagnostics on the Solar system using their survivor's handbook.
We have the Sun. It's a main sequence star. In about five billion years give or take, it runs out of hydrogen in its core. It goes red giant.
Correct, Phase one of the end begins.
Let's do the roll call Mercury and venus.
Engulfed, vaporized, gone. They don't stand a chance. They are deep inside the furnace. Earth is right on the bubble. The Sun will expand almost exactly to Earth's orbit. Some models say it stops just short, some say it swallows us.
And even if it stops short, even.
If it stops just short, the heat will be so intense it will strip our atmosphere and boil the oceans dry. Earth as a living planet is dead. That happens way before the red giant phase, actually just from the Sun getting brighter. But Earth as a rock maybe it survives, but likely those tidal forces we talked about, they will drag it in.
So don't buy real estate for the year five million, twenty six.
Not a recommended long term investment.
Mars.
Mars is further out. It will almost certainly escape the engulfment, but the radiation will toast it. It will be a burnt cinder. It's thin atmosphere long gone.
And then we get to the big boys, Jupiter and Saturn.
This is where the paper gives us hope. Jupiter is at five AU, Saturn is at nine point five AU.
They are in that three to twenty four AU survival beilt.
They are smack in the middle of it, and the Sun is a one solar mass star that fits the progenitor criteria perfectly, and we.
Have decent metal city. Our Sun has all those metals we do.
The Sun is a relatively metal rich star, which is why we have a robust planetary system in the first place.
So Jupiter and Saturn to check all the boxes, they're the designated survivors.
Statistically, yes, we are likely in that lucky three percent, or given our local conditions, that more hopeful eight percent. When our Sun becomes a white dwarf six or seven billion years from now, our inner solar system will be a ghost town, but Jupiter and Saturn will likely still be there.
Orbiting a tiny white point of light in the cold.
In the dark. The Sun will be the size of Earth, casting a pale, weak light, no brighter than the full moon does on Earth today. Jupiter will be freezing, but it will be there.
There is something hauntingly beautiful about that, a quiet, lonely vigil.
It is a solar system of two.
I want to leave our listeners with a final thought. Today, we often look up at the night sky and think about life and civilizations and beginnings. We think about the Goldilock zone for liquid water and biology. There is an end to the story too.
The universe is constantly changing. Nothing stays in the main sequence forever.
I want you to picture that final white dwarf system, a burnt out star no bigger than Earth but super dense, a cold, dark universe around it, and there, silently orbiting in the dark is a massive gas giant, maybe Jupiter, with its great red spot long faded, a silent witness exactly. It's the last witness to a solar system that once hosted life. It's the tombstone, but it's also the legacy, the last thing standing.
And if an alien astronomer looks at our dead solar system seven billion years from now, that is what they will see. They won't see the pyramids, they won't see our skyscrapers, they won't see the Great Wall of China.
They'll see a white dwarf.
And they will see Jupiter, and if their instruments are good enough, maybe Saturn, and they will know this system once was, this system survived.
So next time you look at Jupiter through a backyard telescope or just see that bright, steady dot in the sky, don't just see a planet see the survivor, the one that makes it to the end.
Of the book, the hearty survivor.
Thanks for joining us for this exploration. It's a big universe out there, and sometimes it's good to know what makes it to the end.
Indeed, keep looking up.
Get you next time, Sai.