This is the best of our knowledge, a presentation of national productions.
Although some high school students might disagree with this, science is not a dry topic.
In fact, studying life on Earth or any other planet for that matter has to begin in water.
Three-quarters of the Earth's cover and oceans don't seem pretty wet, but the Earth is actually
incredibly dry.
Today on the Best of Our Knowledge, our Astrobiology series returns with a look at the importance
of water in the study and the origins of life.
We'll also spend an academic minute finding out why humidity makes it harder to keep your
cold drink cold.
I'm Bob Barrett, and this is the Best of Our Knowledge.
Okay, let's repeat that again.
Three-quarters of the Earth's surface is covered in water.
I think we all remember that little factoid from grammar school, but compared to other
planets and extracellular objects our planet is an extremely dry place, which brings
us to our guest today, Dr. Claus Puntopidan, an astronomer from the Space Telescope Science
Institute in Baltimore, Maryland.
He recently joined our Astrobiology series and spoke to our science reporter David Castina
about the importance of water in the solar system.
We're in this fortunate situation in ISS.
Astronomers is that we have the solar system where we can study in an exquisite detail.
We can get rocks, we can send rovers to Mars, but at the same time, new solar systems are
forming right now.
Not that far away.
So my work is observing those, looking at them, and seeing if we can see what the solar
system looked like, so it's like a time machine.
I find that very exciting, and so we all know that water is incredibly important in the
solar system.
What many people may not appreciate so much is that, while they think of Earth, there's
a water-rich place.
Three-quarters of the Earth is covered in oceans.
So it seems pretty wet, but the Earth is actually incredibly dry.
The original material out of which the solar system formed, the solids in that, there was
all a gas, hydrogen gas, but the solid rock and the ice, actually mostly composed of
water.
There's about two times more mass in water and other ice than in rock.
And so if the Earth were to reflect the original composition of the early solar system, the
Earth would be half water.
It's not, it's only 0.1% water.
So it's incredibly dry.
Interesting.
I never even thought about it that way.
And of course, human beings are comprised mostly of water, aren't we?
Right.
It's interesting, because human beings are actually much closer approximation to the
composition of the early solar system.
Interesting.
We are about 70% water, that's practically right.
And they are talking about the whole evolution of things.
Now, let's start at these beginnings.
I know you know, you sit like a time machine, because you're taking these older objects
and you're analyzing what then there are these new solar systems that are forming.
And I think, no matter what you're talking about here, you're talking about very violent
beginnings.
Yeah, well, there's incredible serenity and there's incredible violence.
Explain in the beginning.
And that goes to the core of another thing they're doing right.
So the question is, where does the water come from?
Water forms quite readily before you even form proto-planetary disks, which are the precursors
to planetary systems.
Forms in the coal, interstellar medium, extremely coal, only about 10 or 20 kelvin forms
in the surfaces of dust grains.
And of course, that's a material that you make.
You end up making the proto-planetary disk and the planets from.
However, if you look at solar system material, like so ancient,
material in the solar system, where you can actually, which also have an incredibly fascinating
thing, you can take a meteorite, which is 4.6 billion years old, the oldest rock that
any person on Earth will ever hold in their hands.
And you can find the most primitive ones, right?
You can look inside them, you can see the dust grains that were in the original solar
nebula, actually still there stuck together.
What do they look like?
Tiny dots?
What do they look like?
Yeah, they look like little round things.
And there are also different sizes, right?
There's a millimeter size, they're tiny micron size, we need a microscope to see.
And what are they composed of?
Well, so in meteorites, they're composed of rock, right?
A composed of either silly kits or carbon, but rock, basically.
Okay.
But the point of them is that you can see that they have experienced incredible violence.
There have been melted.
You can see you start out with a gas that was incredibly hot and cooled down and then
you condense the rock out of that.
And so when you talk about violence and serenity, you have this contrast or you have this
quiet cold formation of water in the interstellar medium that can incorporate interstellar
disc.
And you have these violent things happening to it.
And the question is, you know, what planetarium material we see to do the water, we see
an earth, where did it really come from?
Did it come directly from this cold interstellar medium and did it get formed later on in the
disc?
So in other words, the idea of moisture forming because of the heat and the cool, is that
right?
Well, yeah, that actually goes to another thing.
Why don't we talk about just the formation of the actual water molecule here, the chemical
formation of it.
That happens in the cold interstellar medium, but also happens when the gas is very hot.
And so the question is, how did those molecules actually form?
Are they mutually exclusive?
No, there's probably a combination of both things happening.
We just don't know exactly where the water came from on earth, although there are ideas
about that.
In particular, we're also very interested in whether the earth is a common thing.
I mean, other planets that maybe habitable may have gotten a water in a different way.
Sure.
And you mentioned a condensation on whether or not there's another interesting property
of discs that actually have weather in them.
Exactly.
It's a very important property of water in the disc is that discs have temperatures that
span.
It's very cold.
You only have ice to warm or you have the water in the vapor.
And you have very strong temperature gradients.
And so it's very similar to the earth's atmosphere.
And so depending on where in the disc and what the conditions are, you may have places where
the water condenses out of the gas forms snow and it will rain down to the midplane of
the disc.
And you can see this.
Yeah.
And this is how it affects we look for specifically.
We are much better at seeing the steam than the ice.
The ice is hard to see.
We see the steam, right?
So that's what we're looking for.
We basically, if you make the analogy to the atmosphere, we can't see the snow on the
ground, right?
But we can look in the air and we can see whether it's humid or dry.
Right.
A rainforest, you have all the water in the air and you have the humid warm air.
Or you have this cold, arctic place where all the water is frozen on the ground.
It has this dry, clear air.
And we can see the difference between these two interesting.
How does that factor then?
Because you're talking about a proletarian planetary disc.
And the way I understand it, you'll correct me is that there are these dust grains or
these dust particles which solidify and they clump together.
And eventually you're going to form a planet.
In some cases it might not even end up being a planet.
But something called a dwarf planet.
We can get into that later.
But is there any role for the water in that formation?
What is it?
Yeah, water plays probably a key role in that.
And the thing about planet formation is that you need a certain amount of solids.
It could be rock, it could be ice.
You need certain mass.
Sure.
If you have less than that, they're able to grow a little.
But once you get to a certain size, which is about a few feet in size, you can't just
grow them anymore by colliding them randomly because they break apart.
The big snowballs are very fluffy.
They just go poof if they hit another one.
And so this is burials called a meter size barrier.
It's very difficult to pass theoretically.
You grow up to this size and then think just break apart.
I can't you don't end up with this massive planet's hundreds of kilometers in size.
But if you have enough solids, if you're able to concentrate enough of them, and part
of that is the precipitation down to the midplane of the isis, there are ways that they concentrate
radially in the disk as well, there are various mechanisms for that.
You have enough density of solids.
You can reach an instability point for the solids that will create a moon size, a more
size objects.
And of course gravity works here too, doesn't it?
Yeah, so at some point gravity takes over, right?
But for that to work, you need enough.
You need to create the mass for the gravity to grab whole.
Correct, correct.
And so ice plays an important role because that is most of the mass.
So that can make the difference between actually forming a planet's sonot.
If you didn't have the ice there, if it's only the rock, you might not get there.
We've heard of some interesting discoveries even here on our own planet of organisms,
whether they're microbes or bacteria living in really what would be considered uninhabitable
places.
The bottom of oceans, and near vents, in acidic waters.
You've seen those things.
So I think there's a general agreement among the scientific community, the importance of
water in life.
But are there also mediums that are out there that allows life to develop that may not
be water-based?
Yeah, well I'm certainly not the expert on that.
You are studying the water part of this, so you may discover other things as you go.
Right, well that's correct.
So there's water, water is one thing, and it's very important.
And I'm very interested in water, but there are many other molecules, especially what we
call the volatile, which just means they evaporate easily at low temperatures.
Can you give us the names of some of these volatiles?
Well, so carbon dioxide is one, right?
But there's also a lot of organic set of volatile methane.
It's a big one.
Methanol is another big one.
So those compounds of course have crucial importance for the formation of life.
I mean, where the water is the only solvent or not, I think I can't answer.
It's hard, isn't it?
I mean, one of the things I've heard recently is that the more we begin to discover,
and I'm hearing it from your colleagues that are coming into this room, it's like more
needles on the haystack.
There's almost less certainty the more you find out.
Right.
Less certainty I mean about where life is or whether there's, well, where life is about
how all this forms and the processes that are involved.
And you know, whether there's one streamline process or multiple processes or.
Yeah, yeah.
So, so another thing I'm very, very interested in is in that context is, should we really
be looking for earth-like planets, meaning a planet of one earth mass orbiting one astronomical
unit from a solar type star.
So one important type of world that might be incredibly critical is moons around giant
planets.
So we're talking about Europa.
That's right.
Yeah.
So Europa has with its sub surface ocean exactly.
So in our solar system, there's actually more worlds with liquid water that are moons
around giant planets than.
Right.
So as Europa, there is, there are more worlds in the solar system that have liquid water.
And when you say solar system, you mean our source.
Our source.
Right.
But if you extrapolate from that, it's not unreasonable to say that there are just more habitable
worlds in the galaxy than our moons of giant planets.
Which for your research has to have incredible implications since we're not talking about planets
now.
We're talking about moons.
That's right.
So if you want to look for habitable planets, for example, you don't want to exclude
systems that have a giant planet in habitable zone.
You might be inclined to do so if you're only looking for Earth-like planets.
Right.
Because if there's a giant planet in a habitable zone, there wouldn't be an Earth-like
planet.
There wouldn't be dynamically possible.
But even though you can't see them, that planet almost certainly will have moons.
And the moons tend to be icy.
And so it's very likely that there'll be more life in systems like that.
Imagine that you're a life form, you know, and you're a moon in a giant.
You see this gigantic gas giant in the sky along with your star and a whole moon system
around with many.
Well, the implications are just fascinating.
To think about them in our traditional concept, I think of the layperson like myself who
thinks about the solar system and the satellites of planets of being just uninhabitable, rockier,
icy objects that sort of rotate around that planet.
But in fact, they could be the prime places where life could flourish.
Right.
And that's another aspect of my research is in protoplanetary disks is this.
Moons are very difficult to see.
Sure.
And there are tiny things.
There are efforts to try and detect them in around known exoplanets, but it's very
difficult.
Another option is to look for so-called circumplanetary disks.
So circumplanetary disk is an analog of the whole protoplanetary disk around the stars,
only around the planet and that's where you form the moons.
So for example, the moons of Jupiter, that's a mini solar system.
And they got formed out of a disk.
It's just smaller, right?
But otherwise, the properties are very similar to the the the the the the the needle disk and
the solar ampula disk.
But those disks are easier to see.
It's still difficult, right?
But it's easier to see than the final moon system because all the material, if you look
at look for them at a time and all materially still spread out, but that's easier to see
that's a clue that well, at least the potential is there for forming.
So if you detect this, you can you can start to circumplanetary disk where you can start
to think about what material is in there.
And it's actually likely that they're going to be very full of water.
Water rich.
Water rich.
Still to come, David Gisztina's conversation with astronomer Dr. Claus Pondapadan from the
Space Telescope Science Institute in Baltimore, Maryland continues.
That's next on the best of our knowledge.
Got any questions or comments about the best of our knowledge?
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Our email address is knowledge at WAMC.org.
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226 to be sure to ask for the best of our knowledge number 1187.
This is the best of our knowledge.
I'm Bob Barrett.
Our guest today is Dr. Claus Pondapadan, an astronomer from the Space Telescope Science
Institute in Baltimore, Maryland.
He's speaking with our science reporter David Gisztina about the importance of water in
the solar system as part of our astrobiology series.
When I talk to our listeners now about some of the tools in your arsenal here, how do
you go about looking at these things?
What are you using?
Are you using x-rays, spectrometers?
What are you using to see these things and to make your assessments and do your research?
What's amazing thing about water and many other molecules is that they have signatures
all over the electromagnetic spectrum.
Aha.
So we're familiar here in radio with that spectrum because our radio waves are right there
on it.
They are.
Yeah.
They are, you know, the water is going down to millimeter, infrared, to the visible,
to the UV and so on.
And so it's almost doesn't matter which x-ray may be not so much, but beyond, at longer
wavelengths, in the visible, almost doesn't matter which wavelengths you're at, you'll
be able to see water at some wavelengths, depending on the temperature.
And when you say C, what do you mean?
Right.
So we detect molecules using spectral lines.
So we use what's called spectrometers.
We break up the light into its colors and some colors emit more light than others.
And exactly which colors they are, depend on the molecule that we're interested in.
And so that's called a line.
Water has literally hundreds of millions of lines spread all over the spectrum.
Is it an organized set of lines?
What does it look like?
A pattern?
Does it look like a, you know, a jumble?
What does it look like?
There are patterns to it, but it's very complex.
So when you just look at it, it just looks like a pattern.
It's like a mess.
A mess.
Yeah, it's a mess.
So you do need instruments that have a fine resolution, means that they're able to separate
the colors very finely.
Otherwise, it just becomes this, if you look at a forest, the forest is even, you won't
be able to see through the forest.
Sure.
You want to separate the trees, you have to kind of go close to them.
Right.
Got it.
And so I'm mostly working in the infrared region, infrared spectroscopist.
And that's a very, that's a very exciting time right now, because we have lots of new
facilities.
And that's too a large degree really driving this.
This signs about water and disks right now, because now we can actually see it just a
few years ago.
We didn't know that we're water and disks.
That's fantastic.
It was suspect, then, because the solar system is full of water, we didn't know.
Now we know that all disks have lots and lots of water in them.
So that's a new result that's driven by these new, new facilities.
A lot of them are in space.
Yeah, at all, but a lot of them are in space.
And the reason for that is that we have to, if you're on the ground, you have to look
through the atmosphere of the earth and the earth's atmosphere is full of water.
And so it blocks the light.
Water is a very, it's one of the big greenhouse gases actually.
So that's exactly what, there are problems with greenhouse effect.
Right.
You can, that the, the atmosphere absorbs the light from the water.
It goes both, it absorbs it and it goes down and up.
So it's a side effect of my job as an infrared spectroscopist.
Actually, every day, when I use a ground-based observatory, I see the greenhouse effect in
action.
It's just you too as well.
I don't know where to go next, except to say that we've talked about these proto-planetary
disks.
We've looked at the moons of planets and their value being water-rich.
But now we have these other things in our solar system called dwarf planets.
And there's been a lot of focus on these recently.
I believe even in Discover Magazine did a whole feature article on Sirus and the other
dwarf planets and their value to understanding the formation of the universe.
That's right.
Yeah.
Out in the outer solar system are excellent examples of objects that are formed mostly
of water or ises.
Right.
So they're formed well beyond the so-called snow line, right.
The place in the, in the disk where water goes from being vapor to being in, in, in ice
form.
So those are exactly the kind of objects that I'm talking about that you can form through
this instability and the solids that I talked about earlier.
But one of the things, of course, that defines a dwarf planet as its size, but that's
not everything.
You know, we saw recently Pluto, which was determined to be a planet all those years
and then resigned to dwarf planet status, which had so many people upset.
But you know, there are reasons for these designations.
Yeah.
I mean, I think about them as planetesimals, failed planets in a way, right.
I mean, they never grew larger, right.
So proto-planetary disks are thought to form thousands and thousands of mini dwarf planets
of that size originally, right.
And so some of them make it to become bigger.
And so what we see is just the leftovers of the process of, of the forming bigger planets.
And some of these managed to stay big enough, even though they were in places like the
Kuiper Belt, right, where they could be smashing into each other and now we see what's
remaining.
Yeah, you see a remnant, yeah.
Guess it doesn't happen too often that they smash into each other.
Otherwise, they wouldn't be there.
Sure.
There's also, once you've formed this, this disk of planetesimals, right, they interact
with each other.
They don't just directly collide and smash into little pieces.
They scatter, what we call scatters, it means that they get close enough to each other
that they interact, interact curationally.
And so they get their orbits altered.
Interesting.
And that has an effect of throwing a lot of them out.
And so that's why some of these objects could come out of that belt.
Right.
We have the Kuiper Belt, right.
But you also have the odd cloud, which consists of comments which...
Remind people that the odd cloud is.
Right.
Well, this is a located at distances from the sun of 50 to 100 times when I use the distance
of the Earth from the sun.
The odd cloud is tens of thousands of astronomical units out.
So it's really far, far away, out there.
Bigger, way out there, way bigger than the traditional solar system with its planets.
And they weren't formed out there.
They were scattered out there.
They were formed maybe not too far from the snow line really.
Interacted with the giant planets or with each other and got thrown out.
And so they sit there at very low temperatures for a very long time until they may interact
with something that will kick them in once and you get a comment.
Dr. Klaus Pond Topidan is an astronomer from the Space Telescope Science Institute in Baltimore,
Maryland.
He spoke with the best of our knowledge's Science Reporter David Castina as part of our
Astrobiology series on the origins of life.
Our coverage is made possible by the NASA Astrobiology Institute through support from the New York Center
for Astrobiology located at Rensleer Polytechnic Institute in Troy, New York in partnership
with the University of Albany, the University of Arizona and Syracuse University.
You can learn more about all of the topics in our Astrobiology series at origins.rpi.edu.
Okay, so we've determined that water is important.
Hey, it's important to all of us, especially on a muggy day, but humidity makes it tougher
to keep that cold one cold.
And that's the topic of today's academic minute.
Welcome to the academic minute.
I'm Lynn Pascarella, president of Mount Holyoke College.
There's nothing better than an ice cold drink to cool you down on a hot summer's day.
It is Dale Duran, professor of atmospheric sciences at the University of Washington
explains, when it comes to keeping your drink cold, it really isn't the heat.
It's the humidity.
In spring, our skies are filled with puffy cumulus clouds whose turrets grow upward because,
like hotter balloons, they're warmer and less dense in the surrounding air.
But unlike hotter balloons, the warmth inside cumulus clouds is not produced by burning
propane.
Instead, the heating inside a rising turret is produced by water vapor condensing
to form cloud droplets.
We have little intuition about the power of condensational heating, although we commonly
experience the reverse process, evaporative cooling, when our bodies give up the heat
required to evaporate sweat from our skin.
To improve your intuition and to better understand cumulus clouds, consider a 12-ounce
can full of cold beer.
Suppose the can has become covered with a uniform layer of condensation having the thickness
of a human hair.
If all the heat released from this condensation is transferred to the beer, how much does
the beer warm?
A straightforward theoretical calculation gives the answer.
It's 9 degrees Fahrenheit.
How does this actually apply to your canned beverage?
To find out, we measured the rate at which aluminum cans filled with 12 ounces of ice
cold water warmed inside an environmental chamber as we varied the air temperature and
the humidity.
It turns out the rate of condensational heating is indeed significant on hot humid
days.
On a day when the temperature is 87 degrees Fahrenheit in the relative humidity 70%, the
condensation that forms over 5 minutes will heat the cans' contents by 10 degrees, and
this condensational heating will exceed the dry heat transferred from the surrounding
air.
World record humidities are observed near the Persian Gulf and under those conditions, the
5-minute condensational heating increases to 16 degrees.
When your beer is warming on a hot and muggy day, it's not just the heat, it's the humidity.
That was Dale Duran of the University of Washington.
You can find this, other segments, and more information about the professors on our website,
academicminute.org.
Production support for the Academic Minute comes from Newman's Own Foundation in partnership
with Mount Holyoke College.
That's all the time we have for this week's program.
If you'd like to listen again, join us online at our flagship stations website.
Go to www.wamc.org and click on the programs link.
And if you have any questions or comments about the program, send them in.
Our email address is knowledge at www.wamc.org.
I'm Bob Barrett.
Be sure to join us next time for another edition of The Best of Our Knowledge.
Bob Barrett is producer of The Best of Our Knowledge.
Dr. Alan Shartock is executive producer.
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