Cosmic Queries – Cool Worlds with David Kipping

Welcome to StarTalk, your place in the universe where science and pop culture collide.

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This is StarTalk.

Neil deGrasse Tyson here, your personal astrophysicist, and we have our Cosmic Queries edition, a fan favorite.

Chuck, you know it’s a fan favorite.

They love it.

They love it.

They just love it.

Inquiring minds want to know.

That’s what it comes down to, and we put out the expertise of our guest and what the topic is, and then we get flooded with questions.

And today, we’ve got a colleague of mine, David Kipping from up at Columbia University.

In the Department of Astronomy and Astrophysics.

He has tap roots from the UK at Cambridge University and University College London.

And he’s part of what they call the Cool Worlds Lab.

We’re gonna ask him about that.

Okay.

So are you cool or are you not?

A little brag there, a little humble brag.

A little humble brag.

Yeah, we deal with the cool worlds, baby.

David, welcome to StarTalk.

Thank you so much, everyone.

Yeah, the name is not supposed to be like Dope Planet.

So that’s not what we’re going for.

It really is cool, like actually temperature-cool planets.

But I appreciate that we’re kind of cool anyway.

Welcome to Dope-Ass Planet.

You want to be one of us.

You wish you could.

Only some get that one.

Yeah.

Right.

And you’re no stranger to the social media platforms.

You’ve got your own YouTube channel.

It has nearly a million subscribers.

Dude, keep it coming.

That’s all pandemic to thank for that.

I’ve been making these videos for years and people just got into it recently.

David, let’s not be falsely humble.

We can look at you, David.

We know why it’s happening.

We can look right at you, David.

We see the Superman swoop coming across your forehead.

We see it, David.

We understand when you’re the boy band of physics.

There’s a lot of filters happening here to make this happen.

No, Chuck, the real issue here is most people just ate Cheetos and binged on TV shows and he creates an entire YouTube empire.

Man, nice.

There it is.

They’re crazy.

I tried to create a YouTube show on Cheetos and couch dwelling.

Not quite a million views yet.

Not quite a million views, but quite a few.

It has a million million subscribers, but plenty of his videos have millions of views.

That’s not even the thing.

Wow.

So let me ask you, David.

So tell us, what’s the Dope Ass World’s Lab?

We don’t usually go by the name, but Cool World’s Lab is the research team I started here at Columbia.

So there was a team called the Cool Stars Lab in San Diego, I think.

And I thought that was a great name, because obviously it’s a fun play on words, and everyone’s interested in cool stars.

And as we’ve been discovering more and more planets, we know of lots and lots of planets which are close to their stars.

But it’s the planets which are far away from their star, where the temperatures are cool enough that we get really excited, because then you have the possibility of liquid water, all this kind of stuff.

Cool is a relative term, so what would cool be?

Yeah, yeah, yeah.

Quantified.

We’re deliberately vague in that sense.

Yeah, there’s no…

Like, if you’re 301 Kelvin, you’re too hot, but 300 Kelvin, you’re good.

There’s no hard line.

It kind of depends on the science problem.

You know, we’re interested in moons.

That’s one of the big things we’re interested in.

That really doesn’t directly have anything to do with temperature, but actually does kind of work out that way, that when you’re far away from the star, there’s a better chance of moon.

Yeah, but you’re counting Earth as being far away from the sun.

In this…

In this picture.

It’s a cool world in this picture.

We would be, yeah.

All right, so why do we have so many exoplanets that are so close to their host star?

That’s just detection bias, unfortunately.

I mean, I wish it wasn’t true.

All right, tell us about detection bias.

Tell us about that.

Because we hear about bias all the time, and usually it’s some psychological bias.

No one is thinking that there could be actual scientific bias that has nothing to do with whether you’re bigot.

We’re used to it happening at a traffic stop.

Yeah, exactly.

So tell us what you mean by a detection bias.

Yeah, it’s not bigoted astronomers in this case.

That does sometimes happen.

That’s not what’s happening here.

The real problem is that the most successful way of discovering planets is this transit method.

I’m sure you’ve talked about it many times on StarTalk.

The idea of as a plant eclipses in front of the star, it blocks out some of the starlight, and of course the star gets dimmer.

But in order to get that chance alignment, it’s much, much easier if the star and the planet are very, very close together.

When you put them far apart, to get that chance alignment, it’s kind of hard to show, but it’s kind of improbable that the longer the axis is, the less likely is he going to get those two objects to line up.

And so for that reason, the vast majority are far away.

So this is like looking for your car keys under the lamppost, because that’s where you’re going to find them.

So if you’re going to look for planets, you’re most likely to find just those planets that are close by.

And if they’re so close that they’re very hot for being so close to their host star, I guess that’s the problem.

Unfortunately for me, I mean, some folks are fascinated by those hot planets.

I’m obviously more interested in the cooler objects.

On the possibility of life, ultimately.

In part.

I mean, as I said, a big part of one of the reasons I love these things is just exotica can happen out here.

You can have icy rings.

You can have exo moons.

There’s even a paper on the archive that will surely get debunked tomorrow claiming of a Trojan exoplanet at these kind of distances.

So first tell everyone what the archive is, and then tell us everyone about Trojan objects.

There’s a regular posting, an electronic repository called the archive, but it’s archived with an X, and astronomers can post discoveries, papers that they have.

Usually they’ve been through peer review, but sometimes like the paper that was up today, I don’t think it had been peer reviewed yet, and there was a claim of two new planets which happened to be in the same orbit as each other, which would be a new thing.

They’re chasing each other, so that’s called a horseshoe orbit.

And theoretically that’s possible.

I just think a lot of us are pretty skeptical about the data for this particular case.

Gotcha.

All right.

And so then you said something about exomoons?

We have rings, icy rings out here, moons and liquid water life.

There’s all sorts of fun jazz that can happen once you get far from the star.

That’s why they’re cool stars.

Cool worlds.

Sorry, cool worlds.

All right.

So Chuck, you got questions for this man?

I do, as usual.

Let’s jump right into it.

Just to be clear, these are Patreon members who have at least the minimum membership level, which we reduced.

We dropped it down to $5 to give you no excuse.

$5, now you got no damn excuse.

You got no excuse.

$5 a month, and then you get to ask questions.

Okay, go for it.

Here we go for a cool world.

What’s the largest planet that’s ever discovered?

And how large can a planet get, conceivably?

How large could a planet get?

I love that.

That makes sense because our sun isn’t so big.

So are there suns out there that are like super big, and then they have super big planets around them?

There’s a correlation.

Is the sun just a planet around a bigger star?

It passes on its genes almost.

Yeah, not quite.

So let’s track back.

So for planets, usually the biggest planet that was cold, if it was cool, and there was no heat involved or anything like this, pretty much the biggest planet you can get is Jupiter sized.

If you just spoon more mass onto Jupiter, it doesn’t get any bigger.

It just gets more massive and its density increases, but its physical size doesn’t really change.

If anything, it actually gets slightly smaller.

It gets slightly, slightly smaller.

Okay, so often in the public, when people say big, they don’t always know whether they’re referring to size or mass.

I think those are conflated often when people are asking questions in the public.

So you make a very interesting point.

You can increase the mass of Jupiter by spooning matter into it, and the extra gravity actually compresses the gas more than it otherwise would.

Yeah.

So in terms of the maximum mass, let’s just keep spooning mass on.

Eventually it will become a star.

It kind of goes through this period of being a brown dwarf, but I think lots of us think, well, brown dwarfs, that’s kind of a made-up category to some degree.

It’s effectively still just a type of Jupiter, some kind of super Jupiter.

And eventually when you start spooning enough mass on, you’ll get to the critical point, which I think we can all agree something special happens, which is when hydrogen fusion occurs.

There’s enough pressure inside the core of that object that hydrogen fusion occurs, and now you have a star.

And that happens in about 80 Jupiter masses.

You’ve been spooning more and more mass onto it, so therefore the pressures down in the middle keep going up.

Correct.

So about 80 times the mass of Jupiter.

So Jupiter is not close to being a failed star.

People say Jupiter is a failed star.

It has to be 80 times more mass to get.

It’s kind of a long way off, I would say, from being a failed star, but it has a similar size, physical size, to the smallest stars.

That is true.

That is really great.

So Jupiter is really…

That’s it.

Jupiter already has more mass than all other planets combined.

But you’re saying it could have been even more massive, and we’d still call it a planet, and then nothing else matters in the solar system, except the star and Jupiter.

You know what I tell people, Chuck, that Jupiter is more bigger compared to Earth than Earth is compared to Pluto.

So if you’re an Earthling and you want to say, let’s get rid of Pluto’s planet status and you feel good about yourself, if we were Jupiterians, we could feel the same way and kick Earth out and we’d have no recourse.

Right.

Because, yeah.

But also size does matter, so Pluto…

If you really want to get these planets big, you have to add heat.

So you take one of these Jupiters and you park it next to a really hot star.

Well, then it puffs up.

It puffs up.

So then you can get it to something like 170% the size of Jupiter.

So 1.7 times larger.

Probably not quite…

I don’t think we have any ones that are twice as big, but they get pretty close to that.

So a tad under twice the size of Jupiter is kind of our limits for planets, no matter where they are.

As far as we know.

I mean, that’s the fun thing about science.

You never know.

Someone might make a discovery to more than three Jupiter-sized planets.

There’s even ideas of dark matter planets.

Dark matter planets would be extremely large, probably larger than the sun, in fact.

See, now you’re doing your own queries, sir.

You’re doing your own queries, because now we got to know what a freaking dark matter planet is.

I’ve never heard of this.

That’s amazing.

It’s a hypothetical, but dark matter doesn’t like to clump.

It’s very diffuse, it interacts very weakly, and so it’s kind of hard to collapse it down, to cool it down as normal gasses.

When normal gas gets hot, it cools down, it radiates, and so it cools down, the gas collapses, eventually cools down to a point where you can actually start to form stars, because the gasses has concentrated so much.

Dark matter doesn’t really do that, but there are some varieties of dark matter models that allow for a bit more clumpiness.

It’s allowed to kind of interact a bit more strongly.

It’s a fairly extreme idea, but in some extreme versions, it could potentially form a dark matter planet, but it would be larger than the Sun, and of order of just a few Earth masses, and it would be very weakly bound together.

But then what right would you have to call it a planet?

I really don’t care about the name.

It’s a gathering of mass over here.

I don’t know what to call it.

You talked about Pluto.

I never get into that debate.

I’m like, just call it whatever you want.

It’s interesting.

It’s an interesting world.

All right.

We’re going to take a quick break.

When we come back, more questions for David Kipping.

What do we call it, Chuck?

Badass world?

Cool worlds among the exoplanets in our galaxy when StarTalk returns.

I’m Joel Cherico, and I make pottery.

You can see my pottery on my website, cosmicmugs.com.

Cosmic Mugs, art that lets you taste the universe every day.

And I support StarTalk on Patreon.

This is StarTalk with Neil deGrasse Tyson.

We’re back, StarTalk.

Cosmic Queries, The Cool Worlds Edition with the founder of the Cool Worlds Lab at Columbia University, David Kipping.

So David, how many people are part of this lab?

Let’s see, I have three graduate students right now, and at any one time, there’s somewhere between sort of three and six undergraduates.

There’s some stochastic variation in that sense.

All right, so you just invented this out of whole cloth.

Yeah, yeah, I also have an editor as well for my videos.

There’s a whole separate thing of the videos we make on YouTube.

And he edits my videos, but isn’t involved in the research directly.

Yeah.

And what’s the name of your channel?

Just Cool Worlds, that’s it.

Just Cool Worlds YouTube channel.

I wasn’t very creative.

I had this one great idea for a name, and I just kept using it.

Okay, so you shouldn’t have come to me and Chuck.

We would have said dope ass world.

We totally could have hooked you up, you know.

Call next time.

Chuck, you got more questions from our Patreon supporters.

Let’s do it from Patreon.

This is Richard Hart, and Richard says, Richard here from Elk Grove, California.

Elk Grove?

Yeah.

Looking at-

That sounds wealthy, doesn’t it?

Doesn’t that sound wealthy?

It does, Elk Grove, you better have money to live in Elk Grove.

Okay, let me tell you something.

Ain’t no ghetto in the world named Elk Grove.

You ain’t gonna find no hood named Elk Grove, Elk anything.

We’re the Bloods from Elk Grove.

That’s right, we’re the Elk Grove Bloods, that’s right.

Quite frankly, we don’t take kindly to Crips coming this way.

I’m sorry, you’re gonna have to go back to Moose Lane, you Crips, or we’ll give you a stern looking at.

Chuck, that’s the seeds of a whole sitcom, we realize.

Elk Grove for life, bitch.

Anyway, he says, looking at Hano Rain’s exoplanet app, there are more than 300 planets noted in the capital zone of their stars, of which a vast majority of them are at least half the mass of Jupiter or bigger, sir.

Is this just a result of how we’re currently detecting planets, or do you think it’s a potentially common occurrence for a gas giant to be in the habitable zone of its star?

Oh, I like that.

That’s a good question, and it kind of makes sense the way he poses it.

Yeah, that’s definitely something we’re excited about, and it rings true.

I mean, you have to be careful when you look at these catalogs like on the app or on NASA Exoplanet Archive.

It’s another great website if you want to go through all of these yourself.

I’m not sure if Hano is still updating that app anymore, so I’m sure there’s even more actually past that.

But you have to be careful.

Because the total exoplanets are over 5,000.

It seems to me we would have more than 300 in a Goldilocks zone, you’d think.

Possibly.

I’m not sure, but in any case, you have to be careful because of all these biases, these detection biases, that you’re only ever seeing a fraction of the true number.

So people have done the calculation of correcting for that bias, to actually figure out how many planets are there really in this temperate zone.

And it turns out that you’re right, that there are a surprisingly large number, about 50% of all Sun-like stars, FGK-type stars we call them, Sun-like stars, they have planets with radii in between about twice that of the Earth, all the way up to the biggest Jupiter.

So all of those are gas giants, mini gas giants, gas giants, Neptune’s, mini Neptune’s, super Neptune’s, Saturn’s, Jupiter’s, all of that.

So that’s even correcting for the observer’s bias.

Correct.

Half of all stars have gaseous planets in the habitable zone, which obviously don’t have solid surfaces.

That’s something different from what you said.

I thought half of all planets in the habitable zones are that size.

You’re saying half of all stars, oh my God, that’s a whole other.

That’s a lot.

They’re very common.

That’s from Kepler statistics.

For Earth, we don’t even know what the answer is.

Kepler is an orbiting telescope designed specifically for these discoveries.

Correct, thank you.

The NASA mission that flew, what was it, 2009 to 2014-15.

So we know that there are lots and lots of those gaseous planets which could have moons, and that’s why we’re so excited to look for them.

And in fact, there may even be far more than Earth-sized planets at that distance.

We actually don’t know what the number is of how many Earths there are at that distance, yeah.

Wow.

So you like the moons because they give, you like moons of gaseous planets because they give you a surface to hang out on.

Right.

I mean, there could be more habitable moons than habitable planets in the universe.

Aliens could be looking at us thinking, what’s going on over there?

Why are they living on a planet?

Like most of us live on moons.

That’s why they’re not interested in us.

We’re just these weird people living on a planet.

I’m going to say that’s the one cool thing that I like about Star Wars when it comes to how they envision other worlds and galaxies, solar systems, is that often they’re going to a moon of a planet.

They’re not going to that planet.

It’s whatever system, but then where they’re actually landing is a moon itself, you know?

I would also add that the host planet is going to look way better in the sky from a moon than the moon is from the planet.

True.

Just thought I’d tell you that.

Just imagine Saturn in the night sky, looming large.

Wow.

That would just be totally cool.

That is cool.

I always wonder how history would be different had that happened to us.

How would we discover the laws of physics differently?

Celestial mechanics, Kepler’s laws of motions.

Would the presence of such a large body in our sky accelerate it?

Would it decelerate it?

Obviously, there’s all this kind of radio stuff flying off Jupiter as well.

Would that affect the technology we develop on our home planet, our home world even?

It’s right for science fiction.

That’s why Star Wars has so much fun with it.

I think about it the opposite way, David.

If we evolved on the surface of Venus, which is a very thick cloud cover, and it would just get light in the day and dark at night, how much delayed would astronomy have been?

Because you’d have no idea what’s going on outside of this fog.

And we would all have seasonal affective disorder.

So, you know, it’d be like, look up.

Why?

For what?

All right, Chuck, keep them coming.

Let’s go to Matthew Power.

What a great name, Matthew Power.

Since some planets in our solar system have higher concentrations of certain elements, iron on Mars, for example, does that suggest our original solar nebula, once flattened by a centrifugal force, may have been ring-like with bands of certain elements that eventually formed the planets, sort of a solar system size version of Saturn’s rings?

Oh, I like that.

Because that would mean that different places within the ring would coalesce to form a planet and have a very different concentration from other places in the disk.

So how does that all land with you, David?

Yeah, that’s a really interesting question.

In terms of iron abundance, I’ve not heard that before, that Mars has a higher iron abundance than the Earth.

Mercury wins.

Mercury definitely does.

Huge iron core, right.

Usually the explanation we evoke for making sense of what’s going with Mercury is, I mean, generally we kind of assume that all the planets formed with roughly the same amount of iron, at least in a relative sense compared to their mass.

But Mercury does seem to have a lot more iron than the other planets in a relative sense.

And so our explanation for that is that it was basically struck by many, many meteorites with such high velocity, such high energy, they actually chipped away the outer layer of Mercury.

So it was once.

So you’re saying it chips away pieces of Mercury that then just get jettisoned into the solar system?

Correct, or even just vaporized to some degree from the impact and then leaked off as vapor.

That’s also possible.

It’s like a chemical peel for the planet.

So that probably explains, we think, why Mercury has higher ion abundance.

But generally, we assume that for the rest of the planets, it is uniform.

And in fact, that is often treated as a default assumption when we look at other exoplanets.

We assume that there’s every single…

So you don’t know for sure about Mars, though.

You’re not quite sure.

I’m not sure.

I’ve never heard that before.

So I’d have to fact check that Mars…

I always like to be honest when I’ve not heard something before.

I’ve never heard the fact that Mars has a higher ion abundance than the Earth.

I’d be somewhat surprised if it’s true, because just from my expertise of looking at exoplanets, I know that many of my colleagues explicitly assume that ion abundance is uniform throughout any given solar system, with exceptions like Mercury.

We can’t deny Mars the fact that it’s red because of iron in its outer crust.

I mean, everywhere, that’s pretty much just a rusty place.

Right.

Yeah, I think that’s partly due to the unique history of that planet and its distinct chemical environment and the oxidation that happened on its surface.

You said something, you implied something that I want to tease out.

You implied something that I want to tease out here, because it’s a very important scientific tool, really, that you can make a reasonable assumption about how much iron you’d expect in all of the planets based on the iron that’s in the sun, because the sun has most of the mass of the solar system.

Then, if the iron differs from that, you get to then look for an explanation for that, which is a fascinating way to land on a new problem, right?

Yes, yeah.

I mean, I think…

We did that with the moon.

The moon has hardly any iron.

So how do you become an object that big with no iron?

So then we looked and we thought about it, and then we came with the collision hypothesis for the moon.

So it’s fun when something falls out of your expectations.

You get novel accountings for the…

That’s actually why I don’t like this strategy that many of my colleagues have of assuming explicitly that the iron abundance in the star is the same as the planets, because as you just pointed out, there’s already two counter examples right there, and there’s probably even more throughout the solar system.

No, I get that, but if it is different, then you get to look for why it’s different.

True, but in exoplanets, we have no way of directly measuring the iron abundance, at least not yet.

I think the only way to do that would be if the planet was so hot, it was like Mustafar from Star Wars, it was like a lava world where the rock was literally gaseous, and then you could infer the composition of the rock from the atmosphere.

But barring that, we have no way of measuring the chemical composition of what’s inside an exoplanet.

How about Io around Jupiter?

Aren’t there active volcanoes there?

Could you get some?

Yeah, that’s a good example.

Kind of like a Mustafar-ish type system, where you have extreme volcanism, where you can spew up the gasses, and then you get a chance of sampling what was inside.

You need that.

Interesting.

That’s pretty wild.

All right, Chuck, give me another.

All right.

Let’s continue forward.

Here we go.

This is Christian Holmes, who says, greeting Dr.

Tyson and Professor Kipping.

Quick question.

What is the most extreme exoplanet that’s been observed?

Thank you.

Christian from Pennsylvania.

Now, Christian does not qualify the word extreme.

So I don’t know exactly what he means, but maybe, David, you can take liberty with that.

Okay, let me sharpen that question and say, David, you presumably have catalogs of exoplanets now.

There’s more than 5,000.

So presumably they line up with each other in ways that reveal similarities.

Is there an outlier among the 5,000 where nobody else looks like it?

I think it’s hard to pick on one.

There’s several planets which come to mind in this case.

One is one I helped kind of discover its weirdness of.

It immediately comes to mind because it got so much press attention when we released it.

It was like 10 years ago now.

And it was called Trace 2B.

And we called it Erebus, the darkest world.

Erebus was the god of darkness, I think, in Greek mythology.

Or maybe it was Roman mythology.

But we called it that.

Chuck has to say it.

Go ahead.

Erebus.

I like it.

You should do all the press word for that.

Yeah, so this planet is darker than coal.

It’s darker than black paint.

It reflects less light than basically any material you can come across.

Vantablack?

Except for Vantablack.

Except for Vantablack.

But we don’t know, it might be as dark as Vantablack.

We only have an upper limit on its darkness.

It might be even darker than Vantablack as far as we can tell.

What is Vantablack?

It’s the least reflective material that we know of to date.

So it has an albedo of nothing.

No.

Near zero, I guess.

Almost zero.

Wait, wait, so David, if it doesn’t reflect any light, how do you know it’s there?

From transits.

It still casts a shadow.

So as it passes in front of the star, it still blocks out light.

Now that’s a dope ass world.

That’s what I’ll talk about.

It casts a shadow, but it’s very dark.

So when it passes in front of the star, it blocks out light.

When it passes behind the star, we call that the occultation event, you get kind of a moment where you get to detect photons from the planet, light from the planet.

So I can take a picture just here, just before the planet passes behind.

And now I’m getting light from the planet and light from the star.

And I take a photo of the two.

And then I take a photo when it’s behind.

And now I’ve just got light from the star by itself.

So subtract one from the other, and you’ve got light from the planet in isolation.

That is brilliant.

Occultation.

So that’s how we are able to tell that.

God, I gotta love science.

I know.

You gotta love it.

I love it.

I mean, hope makes this crap.

Oh, by the way, just a small fact in there, that it’s very dangerous to subtract and explore the difference between two large numbers.

So you’re there.

So David, your confidence in that, in those results, you have to be very sure that you’re getting what you’re looking for there.

That’s right, but it’s not my first rodeo, Neil.

And it’s been confirmed by others.

Others after me published subsequent work that ended up in the same result.

So we feel pretty confident about that result.

So Chuck, you notice it’s not him reconfirming his own results because what good would that be?

Right.

The whole point of peer review and multiple studies, that’s how science moves.

Science loves the haters, baby.

Yes, we do.

Science loves the haters.

It’s like, go ahead and hate on me.

No, they’re not really haters.

They’re doing it out of love.

Of course.

Of course they are.

They will try to show you’re wrong because they love you.

There you go.

Well, they love science.

Love science.

Well, the truth is, in a way, it is kind of loving because in trying to show somebody’s wrong, you end up confirming their work, and that ends up showing them love.

So, yeah.

All right, one more, Chuck, before we take our second break.

Okay, here we go.

Long ago, I was impressed by a professional.

Oh, this is Gene, and Gene is just Gene, okay?

He goes, long ago, I was impressed by a professional astronomer who was studying eclipsing binary stars.

I was and am amazed by how much info one can extract with careful measurements and clever bootstrapping.

Now we are using the same techniques on exoplanets and the James Webb Space Telescope at spectral measurements of atmospheres.

Could you give a brief summary of what and how we can get details from eclipsing systems?

So, you know, we’re talking about all of it, not just one exoplanet going in front of the star, but the whole system.

The whole star system, all right.

That’s a big question.

However long it’s going to take them to answer, we don’t have time in this segment.

So let’s take a break.

When we come back, we’ll get the full explanation of how the methods, tools, and tactics of eclipsing binary stars have been lifted and adopted and modified in the service of David Kipping’s dope ass planet.

Dope ass worlds.

Dope ass worlds.

When StarTalk Cosmic Fairies continue.

Cosmic Queries, Cool Worlds edition with David Kipping, who started his own Cool Worlds group at Columbia’s Department of Astronomy and Astrophysics, Columbia University, that is.

David, you’ve got your successful and growing YouTube called Cool World.

What else, tell me more about your social media footprint.

The other thing we’re starting, and it’s not live yet, is the Cool Worlds podcast, which I’ve recorded, I think, seven episodes of.

We have seven episodes in the tank, and I’m just really excited to start sharing those.

So as soon as we get that out, you can look on all the major platforms you get your podcast for, the Cool Worlds podcast.

Excellent, excellent.

And you’re on Twitter?

Yes, David underscore Kipping is me on Twitter, yeah.

Okay, so we left off, tell me the chap’s name, Chuck.

Gene.

Gene, well, that could be a boy or girl.

So we do not know the gender.

So Gene wanted to know what methods, tools and tactics were borrowed from eclipsing binaries to serve your cottage industry of Cold Worlds.

Yeah, an enormous amount.

I mean, there’s, in fact, so many astronomers moved from that field of eclipsing binaries into the study of planets directly.

That was the transition around the mid-90s when we first started finding planets.

There’s a really beautiful quote from Henry Norris Russell from 1953, I think he wrote this, that eclipses are the royal road to success.

And they’re kind of a shortcut.

They provide you, it’s almost like a cheat code in the universe.

For some reason, when these eclipses happen, it’s possible to learn so much more about these planets than your technology would seem to enable.

Like we can measure potentially the existence of moons, as we’ve already talked about.

You can measure the atmosphere of the planets.

You can look for rings.

You can even measure the ablateness, whether it’s spherical or football-shaped of a planet from those light curves.

You can measure the surface reflectivities.

We’ve talked about these dark planets.

There’s an almost endless list of wonderful gems.

The eclipses also enable you to see light from the star move through the atmosphere and then do spectroscopic studies.

Correct.

And that’s what, of course, we’re all excited about what JDBS-T is enabling.

So essentially, when the planet passes in front of the same thing as the planet passes in front of the star, some of the light will hit the bulk of the planet, if you like, and it hit the solid surface, and that’s never going to reach us.

That’s the shadow.

But some of it will pass through the atmosphere.

And if it passes through the atmosphere, only a fraction of it will reach us.

And the fraction which reaches us will be different at different wavelengths, different colors.

So our sky is blue, and so the Earth’s atmosphere looks bigger in blue light.

It scatters blue more than it scatters red.

So an alien looking at the Earth and measuring our size would think that the Earth was a little bit bigger at blue wavelengths of light than it was in red wavelengths of light, because a valley is scattering, because our sky is blue.

And then even you have to tell that from afar and go a bit further, you can get the chemicals, you can get oxygen, you can get carbon dioxide, nitrogen.

So you can actually figure out a lot about an exoplanet from afar.

All from eclipses.

Henry Norris Russell was at one point the chair of the Department of Astrophysics at Princeton University.

That’s right, yeah.

Henry Norris Russell.

And the real geeks out there might have heard of the Hertzsprung-Russell diagram.

That’s the same Russell for that diagram.

You can Google it, Hertzsprung-Russell diagram.

HR diagram for short, the affectionate term for it.

All right, cool.

So Gene was right to realize that this trove of information brought to us from eclipsing binaries continues in the field of exoplanets whenever you have eclipses.

There’s a legacy, but it goes even beyond that.

I mean, when you look at the theory that we borrowed from eclipsing binaries, and I studied this, like Copal was one of the founders of understanding elliptical orbits and modeling the durations of the eclipses, the timing procession, the secular, all this kind of complicated celestial mechanics was all figured out for eclipsing binaries.

So we took that and we still use it in exoplanets.

But then we’ve gone further because, of course, we’re measuring atmospheres, we’re looking at planetary atmospheres.

And stars, they have atmospheres, but they’re not nearly as interesting as the atmospheres of planets and all the rich chemical, molecular chemistry that can happen inside them.

I don’t think the stars would agree with you on that.

I think they have…

You just distilled atmospheres.

I may be biased, but I do think planets are infinitely more complex than…

We actually understand stars far better than we understand planets.

We don’t really understand what’s going on inside most planets or how their atmospheres work, how clouds work even on other planets.

But we feel like we have a fairly good understanding of the interior of stars.

Right, because clouds can be made of things other than water vapor.

Right.

Yeah, methane clouds, right?

Which, by the way, I produce daily.

Just in case anybody is wondering.

Okay, no smoking around Chuck.

I am a fire hazard.

All right, keep coming, Chuck.

All right, here we go.

Here we go.

This is Kyla Hunter.

Kyla says, hello, Dr.

Tyson and Professor Kipping.

Could the asteroid and Kuiper belts be considered rings of the sun?

So, you got the asteroid belt, the Kuiper belt.

Well, Saturn has rings, and it’s flat and it’s all around.

And so, we got these two belts here.

What do you think of them, David?

Yeah, I mean, rocky rings, sure.

You could call them that.

I mean, it is possible that planets could have rocky rings.

So, if you’re going to call rocky rings around planets’ rings, I don’t see why you couldn’t call rocky ring structures around stars the same thing.

Sure, you know, the question is how concentrated does it get?

Because normally they form almost like disks rather than or annuli.

They’re not often so narrow.

So, I guess it depends on your structure.

There is actually an exopat that was discovered that has a ring system that forces us to tackle this weird thing of definition.

It was discovered by the WABS survey.

I think it was like J1407B was the name.

And it has a ring system that is…

WABS is a planet survey, right?

Correct.

It’s just small cameras.

It’s just small DSLR cameras.

It’s a consortium of small cameras.

And what is the acronym?

It’s Wide Area Search for Planets, something like that.

We’ll call it WABS.

I was going to say maybe they’re just white cameras.

You know.

That’s from the Zacharines.

We all forget where they come from eventually.

Oh dear, I believe we have to take some pictures now.

Grace is me, I must say.

Shall we take the pictures and then retire to the study?

All right, sorry.

Yeah, this particular planet discovered by WABS has this gigantic ring system that is about the same.

It’s about one AU across.

That’s about the Earth’s orbit around the Sun.

It’s like that’s how large the ring structure around this exoplanet is.

This exoplanet is very, very far from its star and it has a gargantuan size ring system and there’s huge cavities in it.

I’ve seen artist illustrations of this now that you’re mentioning it.

It’s a stunning thing.

How does it keep a stable ring while it’s orbiting the star?

We don’t even know if it is orbiting the star.

There’s only one eclipse of this thing ever seen, which is where the evidence for the rings come from.

It may have just been a chance coincidence that it passed in front of a star and it was free-floating as far as we know.

It could be a brown dwarf, it could even be a small star perhaps.

So there’s an awful lot we don’t know about this particular case.

We just have this one snapshot for this rich apparent ring system and that’s a good point where we don’t know, it’s so different to Saturn.

What do you call that?

Is it a planetary ring system or is it a circumplanetary disk, which is a completely different category normally of how we think about these things that evolve around planets.

So when Jupiter, when it formed its moons, probably at one point had a disk around it and from that disk formed the moons.

Is this something like that or is it more like an ancient ring system, more similar to Saturn?

And so it’s hard, classification is hard.

And if you want to classify the asteroid belt that way, I wouldn’t dismiss it.

Yeah, I think that’s a fair way to call it.

Okay, cool.

Alright, Chuck, we got time for a few more.

Okay, let’s go with Alan Reyer.

What are the major interesting astronomical events that we can expect with respect to exoplanets for the coming year?

I’d love that.

And then he says, Hi, I’m from Lithuania.

Chuck, you probably already killed my last name.

And you’re probably right, but you didn’t give me a phonetic spelling.

So, you’re Alan Reyer.

Or Ryer.

R-A-Y-E-R.

R-A-Y-E-R?

Reyer.

Dr.

Kipping, what can we look forward to?

That might be exciting.

More space missions or just you guys on Earth?

I’m excited.

Let’s see what I’m excited about.

Obviously, JWST is in the sky, observing exoplanets right now.

And it’s observing TRAPPIST-1, which is one of the most fascinating exoplanetary systems we’ve ever discovered.

It probably won’t be sensitive enough to detect signs of life on those planets.

But it could perhaps tell us whether these planets have an atmosphere that is similar, and these are rocky planets in the habitable zone of their stars.

It could tell us whether these planets have an atmosphere similar to a primordial Earth, when the Earth was first born.

It was probably a CO2-rich atmosphere.

It could detect that quite easily.

It could detect a methane-rich atmosphere.

It probably can’t go all the way to detecting oxygen on these planets.

But it’s going to be our first glimpse of the chemical composition of a habitable rocky planet’s atmosphere.

And that’s going to come in the next year, two years from JDUST.

Isn’t that a multi-planet system?

There’s at least seven Earth-sized, in fact, sub-Earth-sized planets in that system.

The seven dwarfs, they’re all packed very, very close to this M dwarf, all within the orbit of Mercury, I think, or seven of them.

So a very, very compact system.

So that’s very exciting.

Then we have Plato, which is a European mission, which is coming down the pipe.

Plato?

Yeah, after the philosopher.

So that’s in 2026, I think.

We’re expecting a launch.

That’s like a super Kepler or even a super test.

These are two missions which NASA launched to hunt for planets by eclipses.

Plato is doing the same thing on steroids.

And then down the road from that we have WFIRST, which is this old spy satellite which was given to NASA.

And it’s basically a Hubble-sized mirror.

The NSA were just like, we don’t need this anymore, because it’s such old technology.

You can have it and do something with it.

So we’ve repurposed it and launching it as basically a Hubble-class telescope that will do all sorts of stuff, including some exoplanet science, using a technique called gravitational microlensing.

So it should find thousands of objects using this technique.

So we’re very excited about that.

And then of course you’ve got Vera Rubin, formerly known as LSST, which is not really an exoplanet mission per se, but I think it could do some interesting things in terms of detecting planets around white dwarf stars.

So the Sun will eventually become a white dwarf star when it dies, and LSST, we wrote a paper about that in my team, we think could be the perfect telescope to detect thousands of rocky planets, even smaller than that, even asteroid sized things around these white dwarfs.

Well, you know what, that brings us to Captain James Riley, who just has a perfect follow up to everything you just said.

If we found biosignatures on an exoplanet, what would be our next course of action considering they’re so far away?

So what do you do?

You’re the dog that caught the car.

So the immediate reaction I would have would be skepticism.

Because I think we’re all going to be devious.

So the first question is it real?

Because we had a biosignature detection already on Venus.

Remember that?

There was phosphine.

I remember that phosphine.

And the reaction that played out after that is probably similar to the reaction that will play out for an exoplanet.

Obviously, we can actually visit Venus.

We could actually potentially go there and do a better job.

But the skepticism that happened I think will be similar to the skepticism that happens with an exoplanet claim.

Well, just in all fairness to the Venus skepticism, that would have been life somehow thriving in Venus’s atmosphere, whereas these other signatures would presumably indicate surface life.

Possibly.

We won’t even know.

I mean, if we detect a biosignature, we don’t know where that life is.

It could be in the ocean and the gases come up.

It could be on the surface.

It could be some kind of whale that floats through the clouds.

There’s no way of telling from the gases alone.

An air whale.

Knock yourself out.

You can have any kind of life you want to explain the biosignature.

And in fact, there are two questions.

Is the signal real?

Can another team get it?

Which has obviously been some problems with Venus, with phosphine.

And then two, even if it is real, does that actually mean it’s life?

Because there are ways that nature can produce biosignatures without biology and just trip you up.

So there will be a decade of arguing and follow-up observations and debates.

And it will get heated of people trying to figure out what’s really going on.

And there will be some false starts.

I guarantee you there will be several biosignature claims that will just not be real.

But that’s okay.

That’s how science works.

Science works through, we’re not dogmatic.

It’s corrective.

We’re allowed to make mistakes and fix it.

And that’s science at its healthiest.

So just expect that down the road.

But eventually, yeah, it would be great if we could one day start imaging these planets, maybe building something like the Luvoire or HabEx that people have been talking about, these kind of supersized telescopes that could image the pale blue dots from many light years away, achieve Sagan’s dream of a pale blue dot from across an entirely different star system.

And then after that, we’ll be trying to learn more and more about it.

Does it have moons?

What’s the continental structure like?

How much water does it have?

We’ll do as much as we can remotely.

And perhaps in the distant future, we might be able to send something.

But it’s certainly not something within our capabilities in the near future.

All right, Chuck, I don’t know if we have time for any more.

I think we’re done here.

Let me check.

Yeah.

We’re done.

We’re done.

But I think…

We got a lot more questions.

Might have to come and do a part two.

Yeah.

I think you have fulfilled our expectation that these are dope ass worlds.

Yes.

We’ll have to rename the whole team, I think, after this starts.

Dope ass world.

It’s a dope ass world.

All right, David, great to know you’re just up the street from us.

Yeah.

Columbia University.

Chuck, good to have you.

Always a pleasure.

All right.

Neil deGrasse Tyson here, your personal astrophysicist, keep looking up.