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