Imagine you're on this alien planet and the ground is like Earth, but the sky.
It's like nothing you've ever seen.
Like colors you can't even imagine.
And you can breathe.
The air is different, but it works.
You know, it's kind of classic sci-fi scene.
But hunting for planets that could have life, I mean, habitable exoplanets.
This is real.
It is.
It's happening right now.
Absolutely.
Welcome to Cosmos in a Pod, space and astronomy series.
All right.
So today we're going beyond the pretty pictures.
We're asking the hard questions like what makes a planet truly able to support life?
Right.
And is our earth similarity index or ESI, is it leading us in the wrong direction?
Well, you've hit a key point there.
Okay.
For years, we were so focused on finding, you know, earth 2.0, a planet just like ours,
size, temperature, everything, the ESI.
It was a good place to start.
Yeah.
Ranking planets based on how similar they are to earth.
Makes sense.
Right.
I mean, earth is the only planet we know with life.
Right.
But as we learn more about exoplanets, we're realizing that looking for earth's twin could
actually be...
It could be a limiting factor.
Yeah.
Limiting our search.
Yeah, absolutely.
The ESI, it's useful, sure, for like initial screening, but it doesn't tell the whole story.
Right.
It's like, you know, judging a book by its cover.
You might miss an amazing story if you just look at the outside.
So what are we missing then?
What's the ESI overlooking when we just focus on a planet that looks like earth?
On paper, at least.
One big thing is the star type.
Okay.
We picture planets, you know, around a nice sun-like star.
Right.
But actually the most common stars are red dwarfs.
Oh, okay.
And these stars, they're smaller and they're cooler than our sun, but they're known for
these huge bursts of energy.
Whoa.
Powerful flares.
That could really mess up a planet's atmosphere in any life that might be there.
So even if a planet is the right size, the right temperature, but it's orbiting a red
dwarf, it could be a totally different situation.
Totally different.
Okay.
Those flares can rip away a planet's atmosphere, leaving it exposed to all the
radiation from space.
Oh, that bad.
Think about it like living in a house with no roof, no walls.
Oh, wow.
Constantly bombarded by the elements.
That doesn't sound fun.
It wouldn't be.
So the ESI misses this whole relationship between a star and its planets.
It really does.
Right.
It's like a snapshot instead of the whole movie.
Exactly.
It's just a snapshot.
Right.
And another thing, the ESI misses.
Okay.
Tidal locking.
Yeah.
This is when a planet, it orbits super close to its star.
Okay.
So one side is always facing the star.
Oh, wow.
The other side is always in darkness.
So it's like one side baking.
Yeah.
And the other side freezing.
Exactly.
Wow.
Some extreme weather then.
You'd have crazy atmospheric circulation.
Oh, wow.
Probably massive storms.
So could life survive that?
I mean, life like we know it.
It makes you wonder.
It does.
I know.
So the habitable zone where liquid water can exist.
Yeah.
It's more complicated than just being in the right spot.
It is.
A planet might be in the zone.
Right.
But if it's tidally locked.
Oh, yeah.
That's a game changer.
Totally different story.
And then there's what the planet's made of.
Right.
The ESI.
It just looks at size and mass.
Yeah.
But it doesn't say what the planet is actually made of.
It doesn't.
So a rocky planet with a molten core like Earth.
Yeah.
Is very different from a gas giant like Jupiter, even if they
weigh the same.
Right.
A gas giant.
Yeah.
Even in the habitable zone.
Not really a place for life as we know it.
Not ideal.
So the ESI.
It's a tool.
Yes.
OK.
But just one piece of the puzzle.
Yeah.
To really get habitability, we need to think bigger.
OK.
Not just look for another Earth.
Embrace the amazing variety of planets out there.
So if the ESI isn't the answer, what is?
What is this new framework for figuring out habitability look like?
Yeah.
What else are we looking at now?
Beyond just copying Earth.
It's about understanding all the things that make a planet able to support life.
OK.
We're going beyond just size, mass, temperature.
We're looking at things like stellar activity.
OK.
Atmospheric composition.
Right.
Even the magnetic fields.
So we're moving from a checklist to a more complete picture.
Exactly.
But it's a lot to think about.
It is.
All these variables.
It is.
It's like solving a puzzle.
Yeah.
A giant cosmic puzzle.
Yeah.
But that's what makes it so exciting.
OK.
Yeah, that's true.
And every new exoplanet we find gives us more pieces.
We start to see the bigger picture.
Oh, cool.
Like take the TRAPPIST-T1 system.
Cool, yeah.
Yeah.
Seven Earth-sized planets all around this tiny red dwarf star.
Tiny star.
It was a huge discovery.
Everyone was talking about it.
Absolutely.
But I remember some debate about whether those planets could actually have life.
Right.
At first, everyone was excited because three of the planets seemed to be in the
habitable zone, the right spot, right place.
Yeah.
But then we had to think about the star.
Oh, right.
The red dwarf.
Right.
And those flares.
Exactly.
Those flares could be really bad.
Yeah.
They could strip away the atmospheres of those planets.
Wow.
So even though they're in the right place, they might not be able to hold on to an
atmosphere.
Exactly.
So no chance for life to evolve.
It makes you question it.
It does.
It's not just about the planet itself.
No.
It's about the star, too.
That's the whole system.
Right.
This balance between being close enough.
Yeah.
But also protected.
You need both.
And it shows that we need to look at the bigger picture.
The long term.
Yeah.
Long term stability.
Exactly.
Not just a snapshot.
Right.
OK.
What about Proxima Centauri B?
Oh, that's a good one.
The closest exoplanet to us.
Right next door.
Orbiting Proxima Centauri.
Our neighbor.
It seemed like we'd found it, you know.
Yeah.
A habitable planet right there.
The jackpot.
But again.
Yeah.
The star is a red dwarf.
Another red dwarf.
And I remember in 2017.
Yeah.
Astronomers saw this huge flare.
Massive.
Coming from that star.
That's one of the biggest we've ever seen.
So even though Proxima B is technically
in the habitable zone.
Yeah.
It could be hit by these flares.
Absolutely.
That could wipe out any life.
It's possible.
Like a neighbor having a fireworks show every night.
Yeah.
Pretty to watch.
Yeah.
But not if you're too close.
Not safe.
It seems like these red dwarfs.
Yeah.
Maybe not the best places for life.
It makes you wonder.
Should we even bother looking for habitable planets
around them?
Well, not necessarily.
OK.
There's more and more research suggesting
that life might adapt even to these extreme conditions.
OK.
Some scientists think life on planets around red dwarfs
might be in underground oceans.
So interesting.
Shielded from the radiation.
Like a hidden biosphere.
Yeah.
Protected from those flares.
Yes.
That's a cool idea.
It is.
Life is resilient.
It finds a way.
Right.
It finds a way.
Yeah.
What about Kepler 186?
Kepler 186.
It's around a red dwarf, but further out.
Yeah.
Potentially more stable.
Earth sized.
About the same size.
We don't know what it's made of yet.
No.
Or if it has an atmosphere.
Not yet.
But it's a good one to study further.
Definitely a candidate.
So each discovery adds more pieces to the puzzle.
It does.
And it's not just about finding another Earth.
Right.
It's about understanding all these different planets.
It's a diversity.
Yeah.
And the potential for life, that's
totally different from what we know.
It's out there.
That's exciting.
That's where the real excitement is.
Right.
This journey of discovery.
It is.
Pushing the boundaries of what we know.
Absolutely.
Changing how we think about life.
It's a challenge.
It's a quest to understand.
Our place in the universe.
And the nature of life itself.
Wow.
And speaking of pushing boundaries.
Yeah.
We can't forget about technology.
Right.
Telescopes like James Webb.
Oh yeah.
And the upcoming aerial mission.
OK.
They're giving us the tools to actually look
into exoplanet atmospheres.
Wow.
So we're not just finding them.
No.
We're analyzing them.
We can study them.
Looking for signs of life.
Exactly.
Wow.
That's incredible.
James Webb is so sensitive.
Yeah.
It can detect water vapor, methane.
OK.
All sorts of molecules that could be signs of life.
So we're like cosmic detectives.
Yeah.
Analyzing clues.
Looking for fingerprints.
To figure out what's out there.
Exactly.
And these new technologies.
They're changing everything.
Yeah.
We're moving beyond the ESI.
OK.
We're developing better ways to measure habitability.
More nuanced.
Much more nuanced.
So we're finally moving past.
Yeah.
Just looking for Earth 2.0.
We are.
And embracing the possibility of life.
That's totally different.
Life as we don't know it.
Yeah.
That's amazing.
It is.
Makes you wonder what kind of life is out there.
The big universe.
Yeah.
Humbling thought.
It is.
But also really exciting.
It is.
It makes this search for habitable planets even more
fascinating.
Absolutely.
It's about understanding all the factors.
Right.
All the things that make a planet able to support life.
OK.
Yeah.
We're going beyond just size, mass, and temperature.
Right.
Looking at things like stellar activity.
OK.
The atmosphere.
Even magnetic fields.
So we're moving from a simple checklist.
Yeah.
To a much more.
A more holistic.
Yeah.
Holistic.
Yeah.
View of what makes a planet habitable.
Exactly.
But that's a lot to consider.
It is.
It's complex.
Yeah.
It's a very complex puzzle.
It is a complex puzzle.
But that's what makes it so interesting.
Right.
Yeah.
I guess so.
And every new exoplanet we discover.
Yeah.
It gives us more pieces.
OK.
We start to see the bigger picture.
That's cool.
Like take the TRAPPIST-1 system.
Oh yeah.
TRAPPIST-1.
With its seven Earth-sized planets.
Seven.
Wow.
All huddled around this tiny.
Yeah.
Ultra cool red dwarf star.
It was a huge discovery.
Everyone was talking about it.
It really captured the imagination.
But I remember there was some debate.
There was.
About whether these planets could actually support life.
Yeah.
At first there was so much excitement.
Right.
Three of them seemed to be in the habitable zone.
Right place.
But then.
But then there's the star.
The star.
The red dwarf.
Exactly.
With those flares.
Those flares yeah.
They could be really intense.
Yeah.
Potentially stripping away the atmosphere.
Oh wow.
Of any of those planets.
So even though they're in the right spot.
Yeah.
They might not even be able to hold on to an atmosphere.
It's a real concern.
So no chance for life to evolve.
It makes you question it.
It does yeah.
It's a good reminder that it's not just about the planet itself.
Right.
It's about the star too.
The whole system.
Yeah the whole system.
It's about finding the right balance.
Yeah balance.
You know between proximity and protection.
Yeah being close enough but also having some sort of shield.
Exactly.
And it highlights the need to look at the long term.
Yeah the long term stability.
The stability of the environment.
OK so another fascinating case study.
Oh yeah.
What about Proxima Centauri b.
Ah yes.
Proxima b.
The closest exoplanet to our solar system.
Right in our backyard cosmically speaking.
Orbiting Proxima Centauri.
Our nearest star.
It seemed like we hit the jackpot.
It did.
A potentially habitable planet.
So close.
But then again the star.
The star.
Another red dwarf.
Another one.
And in 2017.
Yeah.
Astronomers observed this massive flare.
A massive flare.
One of the most powerful we've ever seen.
Coming from Proxima Centauri.
Unbelievable.
So even though Proxima b is technically in that habitable zone.
Yeah.
It could be bombarded.
With these intense flares.
Potentially wiping out any life.
Wow.
It really makes you think.
It's like having a neighbor.
Yes.
Who sets off fireworks every night.
Every night.
Beautiful from a distance.
Sure.
But not if you're standing right there.
Not safe.
So these red dwarf stars.
They seem to be pretty common.
Very common.
But maybe not the best for life.
Makes you wonder.
Should we even bother looking for habitable planets around them?
Well I wouldn't say that there's a growing body of research.
No.
Suggesting that life might find ways to adapt.
Okay.
Even in these extreme environments.
Okay so life could adapt to these really harsh conditions.
It's possible.
Interesting.
For example.
Yeah.
Some scientists think life on these planets around red dwarfs.
Yeah.
Might actually exist in subsurface oceans.
Oh wow.
Okay.
Shielded from the worst of the radiation.
So like a hidden biosphere.
Exactly.
Underground.
Safe from those flares.
Exactly.
That's fascinating.
It is a captivating thought.
It really is.
Life is pretty amazing.
It is.
It finds a way.
Okay so we talked about Proxima B.
Yeah.
What about Kepler 186?
Kepler 186.
Another interesting one.
It orbits a red dwarf star.
It does.
But it's further out.
A bit further out.
Potentially in a more stable region.
Okay.
It's about the size of Earth.
Okay.
Earth sized.
But we don't know for sure what it's made of.
Right we don't know its composition.
Or if it has an atmosphere.
Right.
But it's definitely worth studying further.
Definitely a good candidate.
A prime candidate.
So it seems like each new discovery.
Yeah.
Gives us another piece of this puzzle.
Adds to our understanding.
Of habitability.
Exactly.
And it's not just about finding Earth's twin.
No.
It's about understanding the incredible diversity.
The amazing variety.
Yeah of planets out there.
And the potential for life.
Right the potential for life.
That might be completely different from what we know.
That is exciting.
That's where the real excitement lies.
It's like we're on this journey of discovery.
We are.
Pushing the boundaries of what we know.
Challenging our assumptions.
Yeah and changing how we think about life itself.
Absolutely.
It's a quest to understand.
It is.
Our place in the universe.
And the very nature of life.
Wow.
And speaking of pushing boundaries.
Yes.
We can't forget the role of technology in all of this.
It really makes you think.
It does.
About how huge the universe is.
And all the possibilities.
And all the potential for life out there.
Life we can't even imagine.
It makes our search for these habitable planets.
Yeah.
Even more fascinating.
It really does.
It's a reminder.
Yeah.
That our understanding of life is very earth centric.
It is.
Right we look for familiar signs.
We do.
Planets like our own.
Yeah.
But what if life on other planets is totally different.
What if it's based on different chemistry.
Yeah different building blocks.
Different energy sources.
So we have to broaden our definition of life.
We have to.
Right.
What if there are life forms out there.
Yeah.
That don't need water.
Or oxygen.
What if they thrive in environments we consider toxic.
It's a humbling thought.
It is.
It pushes us to be more creative.
More open minded.
Yeah more open minded in our search.
Absolutely.
So where do we go from here.
What are the next steps.
Well.
In this search for habitable worlds and the life on them.
One thing is even more advanced telescopes.
OK.
Imagine telescopes that can actually see exoplanets.
Wow.
Capture details of their surfaces and atmospheres.
That would be incredible.
We're not there yet.
Right.
But we're getting closer.
It would be revolutionary.
It would.
To actually see those distant worlds.
Study them in detail.
Yeah it would be like going from blurry pictures
to high definition video.
And then we could look for more definitive signs of life.
Exactly not just hints.
Right like actual proof.
What if we could detect artificial light.
Wow.
From a city on another planet.
Or signs of agriculture.
Large scale farming.
That would be amazing.
That would be groundbreaking.
Proof that we're not alone.
It would change everything.
But even if we don't find those definitive signs.
The search itself is valuable.
Right.
It pushes science and technology forward.
It inspires new researchers.
OK.
It helps us understand the universe better.
And our place in it.
Exactly.
It's a reminder that we're part of something bigger.
Much bigger.
Yeah a cosmic story that's still being written.
And the search for habitable planets and life.
Yeah.
That's one of the most exciting chapters.
It really is.
Who knows maybe one day.
Yeah.
We'll find that life is not just common.
But interconnected.
Wow like a cosmic web of life.
Linking us all together.
That's a beautiful thought.
It is.
It keeps us curious.
It drives us.
Yeah it drives us to explore.
Absolutely.
Well thank you for joining us.
It's been a pleasure.
On this incredible journey.
Yeah.
Through the search for habitable worlds.
It's been inspiring.
It has been inspiring.
And thought provoking.
It really has.
Exploring the challenges.
It's a possibility.
And the sheer wonder.
Yeah the wonder of the cosmos.
It's been great sharing this with you.
It has and remember the universe is full of mysteries.
It is.
Keep looking up.
Keep asking questions.
Be curious.
And never lose your sense of wonder.
Never.
And if you enjoyed this deep dive.
Yeah.
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Yeah.
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