from the earliest stages of humankind
we’ve been explorers we search for
what’s past that mountain what’s on the
other side of the ocean we seek out new
experiences new life and new
civilizations and then the last 25 years
we have pushed that exploration past our
earth in order to discover planets
outside of our solar systems we call
these exoplanets stars and planets are
made at the same time big balls of gas
that combined they’re made of hydrogen
and carbon and oxygen and it collapses
in on itself and a star is ignited but
there’s extra material that’s left over
from this expansion so you get dust and
the dust becomes pebbles and they
collide and you get boulders and
suddenly you have a planet but the
planet is linked to its star its Sun not
just by what’s made inside of it because
the planet needs the star’s light and
heat I study the relationship between
planets and their stars in order to find
life and figure out what it really takes
for a planet to be habitable but it’s
really difficult to detect these planets
where life like ours can flourish so we
go on three different things first it’s
the stars then at the relationship
between the stars and the planets and
then finally the composition of the
planets so first we need a stable star
one that’s not too young since a planet
wouldn’t have formed and one that’s not
too old since it would puff up to be a
red giant and it would swallow its star
I’m sorry so it’s planet and we want a
star that’s not too active since it
would have flares and they would reach
out
hit the planet destroying any life on it
recently the Gaia satellite has observed
nine billion stars this is the most
we’ve ever been able to observe it looks
something like this although here I’m
only showing you 3.3 million stars but
it’s because of all of this data that
we’re really able to understand the
sizes the masses and the motion of stars
in our corner of the galaxy on average
we believe that every star has one
planet some might have a lot more like
our solar system and some might have
none but out of all of these stars we
think that 90% of them are stable planet
hosts but like I said trying to find a
planet is so difficult because they’re
tiny compared to their host star it
would let be like trying to see a human
influenced by a raindrop
plus planets don’t give off their own
light so we have to detect them by the
way that they influence their star so
sometimes they pass in front of their
star and the light dims we call this a
transit other times the planets create a
gravitational wobble imagine being
gravitationally influenced by a raindrop
today we have observed 3826 exoplanets
you can see them well that’s about to
show where the blue are from the
ground-based observatories and yellow
are from the Kepler spacecraft but we
aren’t interested in any old kind of
plan it’s something like Jupiter and
Saturn wouldn’t work there’s no solid
surface the gas is toxic and the average
person would feel like they weigh 400
pounds
no we’re interested in something smaller
terrestrial where there is a rocky
surface something like Mercury Venus
Earth and Mars
next we need a planet that’s at just the
right distance from the star for
comfortable temperatures this is called
the habitable or Goldilocks zone because
it’s not too hot and not too cold I mean
I barely survived having leather seats
in my car this is also the region where
we look for liquid water since it’s so
important for life as we know it we
believe that one out of every seven
planets or every seven stars has a
planet in the Goldilocks zone however
all the things that I’ve been talking to
you about have really only to do with
the physical characteristics of a planet
I haven’t really said anything about its
chemical composition and this means the
difference doing having a planet like
Earth and planet like Venus which is
made out of carbon dioxide with sulfuric
acid clouds and as the hottest
temperature of any planet in our solar
system it’s hotter than mercury at 800
degrees Fahrenheit the Earth’s
atmosphere is made up of 78% nitrogen
21% oxygen some carbon dioxide and a few
other things so if we found a planet
whose atmosphere was similar to this
mixture that’d be great but too much
variation and we get a planet that’s icy
like Hoth and star wars or we get a
planet that has steam instead of oceans
I mean you thought humidity in Texas was
bad the amount of carbon dioxide that’s
in our atmosphere is regulated from
earthquakes and volcanoes which happened
because of plate tectonics so this is
the moving and the shifting of the
plates on the surface of the earth
however this motion is then regulated by
the temperature climate of that planet
which in turn is affected by the carbon
dioxide so you see all of these chemical
components of a planet they’re linked
they’re coupled together from the inside
and out in order to regulate the
conditions on the surface the way that I
like to think about it
is that the planets alive it’s moving
and shifting in complex ways however
we’ve only been able to measure about 20
planetary atmospheres out of the 3800
known exoplanets with that being said
I’ve really just been talking to you
about the general definition of
habitability there are a lot of crazy
things that make planetary systems
really complicated for example what if
you had a planet that went around two
stars what what temperature’s be like
when sometimes you see one star and
sometimes you see two we don’t know but
we’ve discovered 21 planets with this
geometry and then what have you had a
moon around an exoplanet we call these
exomoons could life actually exist on a
moon we just discovered one a month ago
and then you have extremophiles these
are creatures that love the frigid cold
and the intense heat what about non
carbon-based life silicon-based life how
would we even characterize that as life
so things are so complicated and there
are so many possibilities but to tell
you the truth we don’t even have the
technology right now in order to measure
the surface of a planet to see this life
to see if there’s iron and magnesium and
silicates for us to walk on but because
stars and planets are made at the same
time we’re able to take the elements
that we measure inside of stars and put
them into models of the planets to look
at their interior structure in
mineralogy
this is actually what I work on so well
it’s a really exciting time to think of
habitability there also a lot of
limitations I mean I started off by
telling you that there are like three
million nearby stars that likely have
planets but we can only measure about a
handful of them which have the right
star the right planet the right distance
the right atmosphere
and that’s to say nothing of the surface
but rather than get depressed about the
things that I clearly have no control
over I think to myself we’ve got to
celebrate the victories as much as we
mourn the losses in my personal life
this means that if I do something great
like publish a paper I treat myself to a
huge sushi feast but sometimes I look to
my science I think of the new advances
and discoveries that we’ve made did you
know that the transiting exoplanet
system satellite will be observing
thousands of planets and the James Webb
Space Telescope will be monitoring those
planets in looking at their atmospheres
really expanding our understanding of
habitability and did I mention we just
discovered a next time on it’s amazing
there’s so much hope in these
discoveries wonderful steps outside of
ourselves that deserve our attention our
celebration our commemoration for what
we can achieve not just as individuals
but as a species there are so many
possibilities so many things to explore
outside of the earth outside of our
solar system outside of our solar
neighborhood and I don’t know about you
but I’m excited for what or who we may
find thank you
[Applause] [Music]
we’ve been explorers we search for
what’s past that mountain what’s on the
other side of the ocean we seek out new
experiences new life and new
civilizations and then the last 25 years
we have pushed that exploration past our
earth in order to discover planets
outside of our solar systems we call
these exoplanets stars and planets are
made at the same time big balls of gas
that combined they’re made of hydrogen
and carbon and oxygen and it collapses
in on itself and a star is ignited but
there’s extra material that’s left over
from this expansion so you get dust and
the dust becomes pebbles and they
collide and you get boulders and
suddenly you have a planet but the
planet is linked to its star its Sun not
just by what’s made inside of it because
the planet needs the star’s light and
heat I study the relationship between
planets and their stars in order to find
life and figure out what it really takes
for a planet to be habitable but it’s
really difficult to detect these planets
where life like ours can flourish so we
go on three different things first it’s
the stars then at the relationship
between the stars and the planets and
then finally the composition of the
planets so first we need a stable star
one that’s not too young since a planet
wouldn’t have formed and one that’s not
too old since it would puff up to be a
red giant and it would swallow its star
I’m sorry so it’s planet and we want a
star that’s not too active since it
would have flares and they would reach
out
hit the planet destroying any life on it
recently the Gaia satellite has observed
nine billion stars this is the most
we’ve ever been able to observe it looks
something like this although here I’m
only showing you 3.3 million stars but
it’s because of all of this data that
we’re really able to understand the
sizes the masses and the motion of stars
in our corner of the galaxy on average
we believe that every star has one
planet some might have a lot more like
our solar system and some might have
none but out of all of these stars we
think that 90% of them are stable planet
hosts but like I said trying to find a
planet is so difficult because they’re
tiny compared to their host star it
would let be like trying to see a human
influenced by a raindrop
plus planets don’t give off their own
light so we have to detect them by the
way that they influence their star so
sometimes they pass in front of their
star and the light dims we call this a
transit other times the planets create a
gravitational wobble imagine being
gravitationally influenced by a raindrop
today we have observed 3826 exoplanets
you can see them well that’s about to
show where the blue are from the
ground-based observatories and yellow
are from the Kepler spacecraft but we
aren’t interested in any old kind of
plan it’s something like Jupiter and
Saturn wouldn’t work there’s no solid
surface the gas is toxic and the average
person would feel like they weigh 400
pounds
no we’re interested in something smaller
terrestrial where there is a rocky
surface something like Mercury Venus
Earth and Mars
next we need a planet that’s at just the
right distance from the star for
comfortable temperatures this is called
the habitable or Goldilocks zone because
it’s not too hot and not too cold I mean
I barely survived having leather seats
in my car this is also the region where
we look for liquid water since it’s so
important for life as we know it we
believe that one out of every seven
planets or every seven stars has a
planet in the Goldilocks zone however
all the things that I’ve been talking to
you about have really only to do with
the physical characteristics of a planet
I haven’t really said anything about its
chemical composition and this means the
difference doing having a planet like
Earth and planet like Venus which is
made out of carbon dioxide with sulfuric
acid clouds and as the hottest
temperature of any planet in our solar
system it’s hotter than mercury at 800
degrees Fahrenheit the Earth’s
atmosphere is made up of 78% nitrogen
21% oxygen some carbon dioxide and a few
other things so if we found a planet
whose atmosphere was similar to this
mixture that’d be great but too much
variation and we get a planet that’s icy
like Hoth and star wars or we get a
planet that has steam instead of oceans
I mean you thought humidity in Texas was
bad the amount of carbon dioxide that’s
in our atmosphere is regulated from
earthquakes and volcanoes which happened
because of plate tectonics so this is
the moving and the shifting of the
plates on the surface of the earth
however this motion is then regulated by
the temperature climate of that planet
which in turn is affected by the carbon
dioxide so you see all of these chemical
components of a planet they’re linked
they’re coupled together from the inside
and out in order to regulate the
conditions on the surface the way that I
like to think about it
is that the planets alive it’s moving
and shifting in complex ways however
we’ve only been able to measure about 20
planetary atmospheres out of the 3800
known exoplanets with that being said
I’ve really just been talking to you
about the general definition of
habitability there are a lot of crazy
things that make planetary systems
really complicated for example what if
you had a planet that went around two
stars what what temperature’s be like
when sometimes you see one star and
sometimes you see two we don’t know but
we’ve discovered 21 planets with this
geometry and then what have you had a
moon around an exoplanet we call these
exomoons could life actually exist on a
moon we just discovered one a month ago
and then you have extremophiles these
are creatures that love the frigid cold
and the intense heat what about non
carbon-based life silicon-based life how
would we even characterize that as life
so things are so complicated and there
are so many possibilities but to tell
you the truth we don’t even have the
technology right now in order to measure
the surface of a planet to see this life
to see if there’s iron and magnesium and
silicates for us to walk on but because
stars and planets are made at the same
time we’re able to take the elements
that we measure inside of stars and put
them into models of the planets to look
at their interior structure in
mineralogy
this is actually what I work on so well
it’s a really exciting time to think of
habitability there also a lot of
limitations I mean I started off by
telling you that there are like three
million nearby stars that likely have
planets but we can only measure about a
handful of them which have the right
star the right planet the right distance
the right atmosphere
and that’s to say nothing of the surface
but rather than get depressed about the
things that I clearly have no control
over I think to myself we’ve got to
celebrate the victories as much as we
mourn the losses in my personal life
this means that if I do something great
like publish a paper I treat myself to a
huge sushi feast but sometimes I look to
my science I think of the new advances
and discoveries that we’ve made did you
know that the transiting exoplanet
system satellite will be observing
thousands of planets and the James Webb
Space Telescope will be monitoring those
planets in looking at their atmospheres
really expanding our understanding of
habitability and did I mention we just
discovered a next time on it’s amazing
there’s so much hope in these
discoveries wonderful steps outside of
ourselves that deserve our attention our
celebration our commemoration for what
we can achieve not just as individuals
but as a species there are so many
possibilities so many things to explore
outside of the earth outside of our
solar system outside of our solar
neighborhood and I don’t know about you
but I’m excited for what or who we may
find thank you
[Applause] [Music]
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