hi
this is rodolfo eric angat your teacher
in earth and environmental science
today we'll be learning about  barycenter
our essential question for this
lesson is
how is the barycenter affected by the
masses of objects
covering standard 1.1.1
in this lesson we aim to achieve
the following targets the first one
i can define barycenter the second one
i can locate the barycenter of the
earth and the moon
the third one i can locate the body
center of different celestial bodies
with different
masses and finally i can explain
how astronomers locate planets
that are not visible let's begin by
defining barycenter
 barycenter is the point between two
objects
where they balance each other it is the
center
of mass or it can also be the center of
gravity
this is where two or more celestial
bodies
orbit each other unlike before
we used to say that the earth revolves
around the sun
or the earth orbits around the sun but
nowadays
we say the earth orbits
around the  barycenter of the solar
system
as all the planets including the sun
do they all orbit around the barycenter
or the center of mass or the center of
gravity
the barycenter is always near
or closer to the more massive object
so you would expect that the barycenter
of the solar system is very close to the
sun
because the sun contains 99.8
of the mass of the solar system so it is
the most massive
object we
can simulate barycenter  by doing the
figures showed on the screen
so you can have a dowel and two
stinks attached to the end of the dowel
like clay of the same mass and then a
string
that's attached to the ceiling and you
will find out
that if the masses of the two objects on
both sides
or both ends of the dowel have equal
masses
then the barycenter would be
in the middle of this one has a bigger
mass
then the body center will be closer to
this
place here and if
this one is the one with the bigger mass
then the barycenter will be closer to
this one
just to review the barycenter
is always closer to the more massive
object
and the barycenter is also known as the
center of gravity
now the  barycenter or center of gravity
as you can see here
this object here has a bigger mass
than this object here thus the body
center
is closer to the bigger object
how about the barycenter of the solar
system
the sun center of mass is deep inside
the sun
itself but the planets do not revolve
around the center of mass of the sun
rather the planets revolve around the
barycenter
in this case it is between jupiter the
biggest planet in the solar system
and the sun the barycenter of the two
is located closer to the more massive
object which is the sun
so this means that the sun itself
revolves around this body center
and jupiter also revolves around this
barycenter
and this is how we show it
this is this object in the middle here
represents the sun
and it is circling around the body
center
of the celestial bodies
as this object too is circling around
the barycenter
of the celestial bodies
how about the earth moon body center
let's watch uh part of this video
so that we would understand how
the earth moon body center goes
besides that's one of our targets right
though we often say that the moon orbits
our earth it is more accurate to say
that both actually orbits their common
center of mass
and that is called the barycenter the
barycenter of the earth
and the moon is actually inside the
earth
it's right here and it's closer to the
surface than to the center
earth revolves around the barycenter
and the moon does the same thing
that barycenter of the earth and the
moon
is the reason why earth is wobbling as
it orbits
and we will be discussing about this
wobbling
when we reach the lesson on precession
that is the barycenter that body center
is about 1710 kilometer
beneath the surface of earth
we will go to the next one now
the  barycenter is located just like
what I said earlier
1000 kilometers
between or rather below the surface
of our planet so the body center
of the earth and the moon is not in the
center of earth
it's actually closer to the surface
at a depth of 1710 kilometers
some internet sites would say 1
700 kilometers some would say 1715
just kind of remember in our
learning we remember the 1710 kilometers
how about the barycenter of the solar
system let's see this one
the solar system's barycenter is very
close to the sun but not at the sun
center
let's watch a part of this video you can
watch the complete video
when you have the time to do so though
we often say
that the planets orbit the sun it is
more accurate to say that the sun
and all the planets actually orbit the
center of mass
of the entire solar system a point
known as the solar system barycenter
this is the sun right here
and as you can see the sun is also
spinning
as it spin it also
revolves or orbits where does it revolve
where does it orbit it orbits or
revolves around the barycenter of the
solar system there it is right there
it goes around this one
so the sun is also wobbling
just like the earth all
all the other planets also
orbit around this barycenter of the
solar system
so remember our star the sun
also orbits and also spins
or we can say it also revolves
and it also rotates and here are the
other planets
revolving around the barycenter of the
solar system
okay again
now we say that the earth revolves
around the barycenter of the solar
system
rather than saying that the earth
revolves around the sun
that is just a simplification
as you can see here it says here 1700
kilometers
this is the earth moon system body
center just like what i said earlier
we will be remembering the 1710
kilometers from the surface
because this is the one that will be
asked in your
nc final exams
the gravity is the one that is pulling
each other
like earth is pulling the moon and the
moon is also pulling the earth
of course the gravity of earth is far
greater than the gravity of the moon
because the mass of earth is far greater
than the
mass of the moon the gravity of of the
moon
is about 17 that of earth
so if you weigh 200 pounds on earth you
will weigh about 34 pounds on the moon
this gravity is also the reason why we
have tides
when we discuss about tides always
remember that gravity
is the reason why we have tides or the
rising
and falling of the water on earth
gravity and the moon's gravity is mainly
responsible for these tides
that's the  barycenter again object one
revolving around the body center
and object two is also revolving around
the  barycenter now let's have some
assessment identify the location of the
barycenter
is it a, b, or c
okay the correct answer is b
so this is the body center this is where
object a
and c revolves
this is the point where they revolve how
about this one
identify the location of the body center
is it a, b, or
c
the location of the barycenter  is
c because this is more
massive than this one so the barycenter
is always closer to the more massive
object
at a certain point it is even inside
the more massive object how about this
one
identify the location of the barycenter
okay so the correct answer is a because
this is the more
massive object remember the body center
is always closer
to the more massive object
how do the body center help astronomers
find other planets moons or
even stars that are not visible with
telescopes
the barycenter
causes the planet or the star or any
other heavenly bodies
to revolve around it and this revolving
causes the heavenly body
or the celestial body to wobble
this wobbling caused by the
gravitational pull
causes the star
to twinkle to to cause some
changes in brightness
the the changes in brightness
and the wobbling is a tell
tale to astronomers
for them to know that a planet or
another star
is hiding like in some solar systems
there are two stars they're called
binary systems
sometimes you won't see the other star
because the
the first star is so bright or their
brightness
mix mixed together but if you see
that the star is wobbling
then that is a sign that there is
another star
trying to pull that star and that is a
clue
that the system is a binary system
okay so just like earth earth is
wobbling
because the moon is there that is also
how they find the moons of other planets
if the planet is wobbling then there is
a certain object close by
was or a certain celestial object close
by that is causing it to wobble
and that makes them
say or hypothesize that there is a
planet
and with that they try everything to
find it
okay so that's the barycenter or the
center of
gravity okay so i hope you are now
confident in answering the questions
good luck in learning thank you so much
bye
