Scale of earth and sun - Science, Class 9 Video Lecture - Class 9 | Best Video for Class 9

My goal in this video
and the next video
is to start giving
a sense of the scale
of the earth and
the solar system.
And as we see, as
we start getting
into to the galaxy
and the universe,
it just becomes almost
impossible to imagine.
But we'll at least
give our best shot.
So I think most of us
watching this video
know that this
right here is earth.
And just to get a
sense of scale here,
I think probably
the largest distance
that we can somehow relate
to is about 100 miles.
You can get into a car for
an hour, hour and a half,
and go about 100 miles.
And on the earth that
would be about this far.
It would be a speck that would
look something like that.
That is 100 miles.
And also to get
us a bit of scale,
let's think about a
speed that at least we
can kind of comprehend.
And that would be, maybe,
the speed of a bullet.
Maybe we can't
comprehend it, but I'll
say this is the fastest thing
that we could maybe comprehend.
It goes about-- and there are
different types of bullets
depending on the type of gun and
all of that-- about 280 meters
per second, which is about
1,000 kilometers per hour.
And this is also roughly
the speed of a jet.
So just to give a
sense of scale here,
the earth's
circumference-- so if you
were to go around the planet--
is about 40,000 kilometers.
So if you were to travel
at the speed of a bullet
or the speed of a jetliner,
at 1,000 kilometers an hour,
it would take you 40 hours
to circumnavigate the earth.
And I think none of this
information is too surprising.
You might have taken a
12- or 15-hour flight that
gets you-- not all the
way around the earth--
but gets you pretty far.
San Francisco to Australia,
or something like that.
So right now these aren't
scales that are too crazy.
Although, even for
me, the earth itself
is a pretty mind-blowingly
large object.
Now, with that out of the way
let's think about the sun.
Because the sun starts to
approach something far huger.
So this obviously
here is the sun.
And I think most
people appreciate
that the sun is much
larger than the earth,
and that it's pretty
far away from the earth.
But I don't think most
people, including myself,
fully appreciate
how large the sun is
or how far it is
away from the earth.
So just to give you
a sense, the sun
is 109 times the
circumference of the earth.
So if we do that same
thought exercise there--
if we said, OK, if I'm traveling
at the speed of a bullet
or the speed of a jetliner,
it would take me 40 hours
to go around the earth.
Well, how long would it
take to go around the sun?
So if you were to
get on a jet plane
and try to go around
the sun, or if you
were to somehow ride a
bullet and try to go around
the sun-- do a complete
circumnavigation of the sun--
it's going to take
you 109 times as long
as it would have taken
you to do the earth.
So it would be 100
times-- I could do 109,
but just for approximate--
it's roughly 100
times the circumference
of the earth.
So 109 times 40 is
equal to 4,000 hours.
And just to get a sense of
what 4,000 is-- actually,
since I have the calculator out,
let's do the exact calculation.
It's 109 times the circumference
of the earth times 40 hours.
That's what it would take to do
the circumference of the Earth.
So it's 4,360 hours to
circumnavigate the sun, going
at the speed of a
bullet or a jetliner.
And so that is-- 24 hours in
the day-- that is 181 days.
It would take you
roughly half a year
to go around the sun at
the speed of a jetliner.
Let me write this down.
Half a year.
The sun is huge.
Now, that by itself may or may
not be surprising--and actually
let me give you a
sense of scale here,
because I have this
other diagram of a sun.
And we'll talk
more about the rest
of the solar system
in the next video.
But over here, at
this scale, the sun,
at least on my screen--
if I were to complete it,
it would probably be about
20 inches in diameter.
The earth is just this little
thing over here, smaller
than a raindrop.
If I were to draw it on this
scale, where the sun is even
smaller, the earth
would be about that big.
Now, what isn't obvious, because
we've all done our science
projects in third and fourth
grade--or we always see these
diagrams of the solar system
that look something like this--
is that these planets
are way further away.
Even though these are
depicted to scale,
they're way further
away from the sun
than this makes it look.
So the earth is 150 million
kilometers from the sun.
So if this is the sun
right here, at this scale
you wouldn't even be
able to see the earth.
It wouldn't even be a pixel.
But it would be 150 million
kilometers from the earth.
And this distance right here is
called an astronomical unit--
and we'll be using that
term in the next few videos
just because it's an easier
way to think about distance--
sometimes abbreviated
AU, astronomical unit.
And just to give a sense of
how far this is, light, which
is something that we think
is almost infinitely fast
and that is something
that looks instantaneous,
that takes eight minutes
to travel from the sun
to the earth.
If the sun were to disappear, it
would take eight minutes for us
to know that it
disappeared on earth.
Or another way, just to put
it in the sense of this jet
airplane-- let's get
the calculator back out.
So we're talking about
150 million kilometers.
So if we're going at
1,000 kilometers an hour,
it would take us 150,000
hours at the speed of a bullet
or at the speed of a jet
plane to get to the sun.
And just to put
that in perspective,
if we want it in days,
there's 24 hours per day.
So this would be 6,250 days.
Or, if we divided by
365, roughly 17 years.
If you were to shoot a
bullet straight at the sun
it would take 17
years to get there,
if it could maintain
its velocity somehow.
So this would take a
bullet or a jet plane
17 years to get to the sun.
Or another way to visualize
it-- this sun right over here,
on my screen it has about a
five- or six-inch diameter.
If I were to actually do it
at scale, this little dot
right here, which
is the earth, this
speck-- I would have to
put this back about 50 feet
away from the sun.
50 or 60 feet away from the sun.
If you were to look
at the solar system--
and obviously there's other
things in the solar system,
and we'll talk more about
them in the next video--
you wouldn't even
notice this speck.
This is a little dust thing
flying around this sun.
And as we go further and further
out of this solar system,
you're going to see even
this distance starts
to become ridiculously small.
Or another way to
think about it--
if the sun was about this size,
then the earth at this scale
would be about 200
feet away from it.
So you could imagine, if you
had a football field-- let
me draw a football field.
These are the end zones-- one
end zone, another end zone.
And if you were to
stick something--
maybe the size of
a medicine ball,
a little bit bigger than a
basketball, at one end zone--
this little speck would
be about 60 yards away,
roughly 60 meters away.
So it's this little speck.
You wouldn't even notice it
on the scale of a football
field, something this size.
Anyway, I'm going
to leave you there.
Hopefully that just
starts to blow your mind
when you think about the
scale of the sun, the earth,
and how far the earth
is away from the sun.
And then we're going to see
even those distances, even
those scales, are super
small when you start thinking
about the rest of
the solar system.
And especially when we start
going beyond the solar system.