Our Lone Star Understanding the Vastness of Space
[Music]
[Applause]
i moved to texas six years ago to take
my job here at austin college
and being an astronomer i was the butt
of several jokes
moving to the lone star state
but i think my brother-in-law said it
best
when he said poor david
with only that one lone star to study
now
here is that lone star the main subject
of my talk tonight
today and what you probably know better
as the sun
but what you may be wondering is why i
call the sun
lone what makes our sun so lonely
but perhaps more vitally who cares
so to answer the first question the
reason our son is so lonely is because
space is so big and i’m going to be
describing that
that’s the point of my talk tonight but
let me address the second question now
who cares the people who care are people
who
have an interest in space they’re the
people
who love to learn about space missions
missions to mars
missions to the moon the dragon capsule
and who want more they’re the people who
create science fiction
and of the people who devour science
fiction
they’re the engineers who actually build
the space capsules that our astronauts
go up in
and the young people who hope to one day
help with that endeavor
all of these people people the space
people
whether dreamers or doers have one thing
in common
a fascination with what lies beyond
and i’m going to give you a look at that
beyond i’m going to give you a cold hard
look at the vastness of space
but to start i think i want to begin
with the popular view
of the cosmos if you look at
a video online youtube or you’re
watching a movie or a television show
probably what you’re going to see
is something where everything is really
close together you see a perspective
with lots of planets nearby one another
and of course there’s always warp speed
right so it doesn’t take very long to
get from place to place
but the reality is quite a bit different
from these imaginings
to give you one example the distance
between the earth
where we are and the sun our lone star
is 94 million miles
94 million miles
you all know how long it takes you to
run a mile right
imagine running that mile okay now try
imagine running for
94 million of them that would take
longer
than your life so there’s no real way to
conceive of that number
you can think of that number but it
really actually doesn’t make a great
deal of sense it’s just
a number and to give you a second
example
the nearest star outside of our solar
system is 4.2
light years away but again we have a
problem because what is a light year
when light in our everyday life is
instantaneous you turn on the lights
the lights are on light moves too fast
to understand that number two
so we need some kind of context for
understanding
how big space is to put it in the form
of a scientific question we could ask
can we conceptualize the size of space
so that’s our question and this is my
best answer to that question
so here’s what we’re going to do we’re
going to shrink the sun
down to the size of this basketball so
now you know why it’s finally here
if the sun were the size of this
basketball
then where would the earth be and how
big is it
that 94 million miles shrinks down to a
mere
25 meters which is outside this theater
in the old art gallery beyond
25 meters away and on this scale the
size of the earth is only the size of a
nerd candy or the cross-section of a
sprinkle on your ice cream
earth is tiny it’s absolutely tiny and
really far away
between this sun and earth
there are of course two other little
things mercury
would be about the middle of the first
section here and venus would be about
the middle of the second section back
there
and for everything inside of earth’s
orbit that’s it that’s all there is
in the inner solar system
mars of course is a little further on
but the biggest planet in the solar
system
is jupiter on this scale jupiter is
about the size of a small marble
located 120 meters away which is in the
right campus center
two buildings over saturn is twice as
far away
as jupiter we’re still on campus
uranus is twice as far away as saturn so
now we’re off campus
and neptune is three times saturn’s
distance
on this scale neptune would be
a half a mile away and this red circle
represents
a radius of one half mile
around this position right here
one half mile in every direction and we
have all eight planets
a mile from end to end of that circle
and we have a basketball
a couple of marbles and some other
things too small to otherwise be noticed
suddenly social distancing doesn’t seem
too far away does it
[Music]
the solar system actually keeps on going
this is not the edge of the solar system
the edge is what’s known as the
heliopause which is an ill-defined
region
way way out there on this scale three
kilometers or almost two miles
that’s this big circle
and between neptune’s orbit half a mile
away
and the heliopause almost two miles away
there’s a smattering of comets the size
of dust grains
very slightly larger dwarf planets and
that’s it
so that’s our solar system in a nutshell
of course the real question before us
though
was why is our star lonely
our lone star so let’s talk about that
next nearest star to the sun
it has a name it’s called proxima
centauri
and proxima centauri is 4.2 light years
away as i’ve already said
one thing you might be interested in
knowing is if the sun is as big as a
basketball proxima centauri is the size
of this ping-pong ball because stars
come in different sizes too
so what do you think 4.2 light years
away how far away is this ping-pong ball
from this basketball
it has to be outside the solar system so
it has to be more than two miles right
what do you think 10 miles
100 miles i can sense that you know
where i’m going with this
four thousand three hundred miles away
if we tried to put this on a map of the
earth we could choose a few places to
put it for instance
let’s go west it would be in the pacific
ocean
halfway between the hawaiian islands and
midway atoll
if the basketball were here
or going south we’d be in south america
in northern chile the city of
antofagosta which is on the tropic of
capricorn
or if we go eastward towards europe it
would be almost all the way
to the west coast of ireland
and i wanted to sink in for you that
between this basketball
our sun with its planets
and moons and asteroids and comets out
to a distance of two miles
and this next nearest star proxima
centauri
there’s nothing empty black
space devoid of life devoid of anything
to look at
think about that the next time you’re on
a long car ride
or a flight because if you left your
basketball son at home
you’d be on an interstellar adventure
of the most boring kind because unlike
your car ride
unlike your flight there would be
nothing to see
you’ve all heard of the milky way galaxy
it’s where we live
along with about 100 billion other stars
or so
i’ve marked about where the sun is
halfway between the center and the outer
edge of the milky way galaxy
but once again we’ve encountered this
problem with numbers i’ve quoted a
number
100 billion and again that is like
no number that you have experience with
in your everyday life
and so let’s even just try to understand
it based on the analogy i’ve already
used
if every star is a basketball or a
ping-pong ball or some other type of
ball
and each of them is separated and this
is actually pretty accurate
by a distance similar to us between
between us and
proxima centauri
i can’t conceive those kinds of
distances 100 billion stars 100 billion
basketballs
each of them separated from one another
by 4 000 miles or more
space truly is incomprehensibly large
so here we are on this tiny speck of
rock called
earth orbiting a really far distance
from our sun
and all the stars that we see at night
they’re all further away than proxima
centauri is
and i have to be brutally honest about
this one
we do not have the technology to visit
those places
space people everywhere that is one of
your limits
perhaps the most important limit
and now that we have defined that limit
we can begin to dream how to go past it
how to conquer it creators of science
fiction
imagine your worlds
with this science fact forget warp drive
forget putting things closer together
deal with space as it really is there’s
a compelling
human story about crossing that about
making that an
endeavor and engineers present
and future start planning
for how we’re going to have the energy
to go these long distances
and how we’re going to sustain life for
those long
journeys because if we collectively
believe that we can
we will
and those first people who go on a ship
heading out into the stars
to land on some other planet around some
other star
they will have been assisted by an army
of scientists and engineers
and they will be buoyed by the hopes and
dreams of all of humanity
left behind here on earth it will be a
shared victory
and i call that seeing beyond
thank you
you