Scale of Solar System

Where we left off
in the last video,

I think we were getting a
reasonably good appreciation

for how huge the
sun is, especially

relative to the Earth, and
how far the Earth is away

from the sun.

That most of these diagrams that
we see in science textbooks--

they don't give justice.

In fact, when I showed
this sun over here

that was about five
or six inches across,

I said Earth would be just this
little speck, about 40 feet.

It wouldn't be this distance.

It would be about 40 feet
to the left or the right.

Or its orbit would have a
radius of about 40 feet.

You wouldn't even
notice it if you

were looking at this
thing over here.

It would be this
little speck orbiting

at this huge, huge distance.

If you look at
this sun over here,

if I were to draw
the whole sun, it

looks like it would have a
diameter of about 20 inches.

So in this situation, this
Earth right here-- and this

is drawn to scale--
this Earth would not

be anywhere near this close.

It would be about 200
feet that way, or about 60

or 70 meters, 60 meters.

So you can imagine if the
sun was this size, sitting

on something like
a football field,

this little speck of an Earth,
this little thing right here,

would be sitting on the other
40-yard line, 60 meters away.

So you wouldn't even notice it.

You might notice
this from a distance,

but you wouldn't even
see this thing over here.

And the other planets
are even further.

Well, not all of
the other planets.

Obviously, you have Mercury.

I think most of us are
familiar with these.

But I'll just list them
here, just in case.

That's Mercury.

This is Venus.

Mercury is the smallest of
the planets where it's not

debated whether it's a planet.

Pluto is the smallest,
but some people

debate whether it's
really a planet or just

a large solar body
or a dwarf planet

or any of those type of things.

But then you have Venus,
probably the closest in size

to the Earth.

Or it is the closest
in size to the Earth.

And then you have Mars.

And then you have Jupiter.

And just to give a
sense of, once again,

how far these things
are, if I were to go back

to the analogy of this
being the size of the sun,

then Jupiter is five
times further than Earth.

So this would be-- If I were to
actually do the scale distance,

this would be 300 meters away.

So if I had a nice, big,
maybe medicine-balled-size sun

right over here, maybe
basketball-sized.

A little bit bigger
than a basketball,

this looks on my screen--
then this little thing

that's smaller than
a ping pong ball,

I would put this three
football fields away.

That's how far Jupiter is.

And then Saturn's about
twice as far as that.

Saturn is about nine
times the distance.

So let me make it clear.

The Earth is one astronomical
unit away from the sun,

roughly.

Its distance changes.

It's not a perfectly
circular orbit.

Jupiter is approximately
a little bit--

5 plus astronomical
units-- a little bit

more than five
times the distance

of the sun to the Earth.

And Saturn is approximately
nine astronomical units,

or nine times the distance
from the sun to the Earth.

So once again, this would be
nine football fields away.

Or another way to think about
it would be, essentially,

a kilometer away.

If we had kind of a
medicine-ball-size sun,

this little smaller
than a ping pong

balled Saturn would
be a kilometer away.

And I just want to
really reiterate

that because you never
visualize it that way.

Because just for
the sake of being

able to draw it
on a page, you see

diagrams that look like this.

And they really don't give
you a sense of how small

these planets are
relative to the sun,

and especially relative to
their distance from the sun.

And then after Saturn, you
have Uranus and then Neptune.

And obviously, these
guys are even further.

And just to give
you a sense, it's

very easy to start talking about
galaxies and universes and all

of the-- or the universe.

But I really just
want to get-- already,

what we've talked about, we're
talking about huge distances,

huge scale.

We already talked about that it
would take a jet plane 17 years

to travel from the
Earth to the sun.

Multiply that by
five, about 100 years

to go from Jupiter
to the sun, 200 years

to go from Saturn to the sun.

So you could have had Abraham
Lincoln get into a jet plane,

and if he left from
Saturn, he still

would not have
gotten to the sun.

So these are huge,
huge distances.

But we're not done with
the solar system, there.

Just to give a sense of
scale-- so this right here,

that's the sun.

And each of these
planets are actually

narrower than these orbits.

So they just draw
these orbits here,

but you wouldn't actually
even see the actual planets

here at this type of a scale.

But this is one astronomical
unit right over here,

the distance from
the sun to the Earth.

Then you have Mars.

Then you have the asteroid belt.

There you have
the asteroid belt,

which also has some pretty
big things in it, itself.

And it has these things that
are kind of considered almost

dwarf planets,
things like Ceres.

You could look those
type things up.

And then you have
Jupiter out here.

And once again, we said it
would take 100 years, or roughly

100 years, for a jet plane to
get from Jupiter to the sun.

But even if you
take this whole box

here-- which is a huge amount
of distance, of roughly about

five astronomical units-- it
would take about 40 minutes

for light to get from
the sun to Jupiter.

So this is a huge,
huge distance.

But even this huge
distance-- we can put it

into this little
box right over here.

So this whole box right over
there can be fit into this box.

And you need to do that
in order to appreciate

the orbits of the outer planets.

And so on this scale, Earth
and Venus and Mercury and Mars,

their orbits look pretty
much-- you can't even

differentiate them from the sun.

They look so close.

They almost look
like they're part

of the sun when you look
at it on this scale.

And then you have you
have the outer planets--

Saturn, Uranus, Neptune.

And they we have a Kuiper belt.

And this is more asteroids, but
these are kind of more frozen.

And when we think of ice, you
always think of water ice.

But out here, it's so cold.

And it's relatively
getting dark, now,

because we're pretty
far from the sun

that things that we normally
associate as gases are going

to be in their
solid form out here.

So this isn't just
rocky elements.

This will also be things that
we normally associate as gases,

like methane, frozen methane.

But even here, we're not done.

We're not even out of
the solar system yet.

And actually, just to give
you a sense of the scale we're

operating right here, I
have this chart right here

from the Voyager mission.

So the Voyager missions--
Voyager 1 and 2-- actually,

Voyager 2 left a little bit
earlier, a month earlier.

Voyager 1 is just
traveling faster.

They left about a
year after I was born

And their current
velocity, just to give you

a sense of how fast--
Voyager 1 right here is right

now traveling at 61,000
kilometers per hour.

That's about 17
kilometers per second.

The size of a city every
second-- it's going that fast.

That's, at least in my mind,
an unfathomably fast velocity.

This thing has been
traveling roughly that fast.

It's been going around planets
and gaining acceleration

as it went around orbits.

But for most of
the time, it's been

going at a pretty fast speed.

And just to translate
it to people

who don't relate to
kilometers, that's

about 38,000 miles per hour,
so this huge, huge unfathomably

fast speed.

And it's been doing
it since 1977.

I was learning to walk.

And when I was
learning to walk, it

was traveling at this
super fast speed.

And then when I was learning
to talk-- our whole lives,

when we're sleeping,
everything, we're eating,

I'm in elementary school--
it's still rocketing out

of the solar system
at roughly this speed.

Its velocity has
changed, but especially,

once it got outside
of the planets,

it's been roughly
at this velocity.

So it's just been rocketing out.

And I don't want to say only,
but it's gotten this far.

If we look at it
on this scale, it's

gotten about that
far right there.

It's about 115, 116
astronomical units.

And to give a sense-- so there's
two ways to think about it.

One says, like, wow,
that's really far.

Because we know that
even on this scale,

you can't even
see Earth's orbit.

So this looks like it's a
pretty, pretty far distance.

And just to give you a sense of
how far 116 astronomical units

are, if 2,000 years ago,
Jesus got on a plane--

I actually cut and
pasted a copy of Jesus,

just for visualization
purposes--

but if he'd got on a jet liner
at 1,000 kilometers per hour

and went straight
in that direction,

in the direction that Voyager,
Voyager would only just now be

catching up to Jesus.

So this is a huge, huge,
huge, huge distance.

But at the same time,
even though it's

a huge distance, especially
relative to everything

else we've talked about,
relative to just even

the outer reaches
of the solar system,

we're still talking in
terms of a small scale.

So that's how far Voyager is.

And just to give a sense, on
this scale-- so this whole box

over here can be
contained in this box.

And when you look at
this box, Voyager's

only gotten about that
far after traveling

at this unbelievable
velocity for over 30 years,

for about 33 years.

And just to give you an idea
of these other things, Sedna,

right here, is a reasonably
large-sized outer solar system

object.

It's one of the
furthest objects that we

know of in the solar system.

And it has this very
eccentric orbit.

So it gets-- I don't want to
say relatively close, but not

unreasonably far away.

And then it gets really
far away from the sun.

But even Sedna's orbit-- so
if I were to look at this,

so this whole box over here can
be contained right over here.

So in this diagram
right here, you

wouldn't even be able to see.

It would be like a
speck how far Voyager

has traveled in 33 years
at 38,000 miles per hour.

You would not even
be able to notice.

You wouldn't even
notice that distance.

And even though you can't
even notice that distance,

we still have the
sun's influence.

The gravitational pull is
still attracting things to it.

And this right
here, we speculate

that there is the Oort cloud.

And this is where the
comets originate from.

And this is just a
bunch of frozen gases

and ice particles
and things like that.

But we're starting to
get to the outer reaches

of the solar system.

And this distance right here
is about 50,000 astronomical

units.

And just to give a
scale-- because you

hear a lot about light years
and all of that-- light years

are about 63,000
astronomical units.

So if you go a light
year out from the sun,

you'll end up in the Oort cloud,
the hypothesized Oort cloud.

And just to give a
sense, another scale,

the Oort cloud is actually--
most of the planets' orbits

are roughly in the same plane.

But this right here is
the orbit of the planets.

And once again, these
lines are drawn too thick.

They're just drawn the
thinnest possible so

that you can see them, but
they're still drawn too thick.

And this gets us all the
way to the Kuiper belt.

But all of this over
here, so all the way

out to the Kuiper
belt, all the way out

to all of the major
planets-- this

is Pluto's orbit
right over here.

This whole diagram is only
sitting in right over there.

You can barely see it.

This whole diagram is
just that dot in this.

And then you can see the
Oort cloud all around it.

And it's more of
a spherical cloud.

And we think it exists.

Obviously, it's hard to observe
things at that distance.

So hopefully, that gives
you a beginning sense

of the scale of
the solar system.

And what's really going to
blow your mind-- if this hasn't

blown your mind already--
is that this whole thing's

going to start
looking like a speck.

When you even just look at the
local area around our galaxy,

much less the galaxy, much
less the universe as a whole.

Anyway, I don't want
to get-- well, anyway.

This is starting to get crazy.