Download 1Barycenter Our solar system consists of the Sun and the

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Barycenter
Environmental Science
Name: _________________________________________ Period: ________ Date: _______________
Essential Question: How is the barycenter affected by the mass of the object?
Instructions: Read the selection and answer the questions.
Our solar system consists of the Sun and the many millions of celestial bodies, including
large planets and microscopic dust particles, which orbit around it. As a unit, the solar system
has a center of mass, its balancing point. At this point, the system would balance like a spinning
plate atop a circus performer's balancing stick. This point, called the barycenter, is the exact
point about which all the bodies in the solar system orbit. Since the Sun is vastly larger and
heavier than all the other bodies combined, the solar system's barycenter is very close to the
Sun—but not at the Sun's center. Thus, while all the other solar system bodies seem to orbit
the Sun, they, including the Sun, are actually orbiting a point in space just beyond the Sun's
outer layer.
Did You Know that the Moon Doesn’t Orbit the Earth?
Orbit means to move in a curved path around another something. In astronomy, celestial
bodies are generally described as moving or orbiting some other celestial body. For example, the
Moon is said to orbit or revolve around the Earth. The Earth doesn’t stays in position as the
Moon circles it.
Just like the planets orbiting the Sun,
moons orbiting planets also comprise a
system with a center of mass. For the EarthMoon system, the barycenter is located 1,710
km below the surface of the Earth. This is
because the Earth is far more massive than
the Moon and it is this common center of
mass around which the Earth and the Moon
seem to go around. The International
Astronomical Union (IAU) does not consider
the Earth-Moon system as a double-planet
system, since the center of mass does not lie
between them but rather within the Earth.
A Method to Locate Planets
Astronomers are using the concept of the barycenter to locate new planets around stars
outside our Solar System. The way this is done is that since a planet and its star orbit a common
center and due to the star being more massive, the center of mass is located within the star
itself. This actually causes the star to "wobble" in its path and it is this tell-tale signature of
wobbling of stars that tells astronomers that a planet is causing the effect. Many extrasolar
planets have been located around various stars in our own galaxy making the barycentric
approach a useful and practical means of planet hunting.
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R.Angat
http://www.brighthub.com/science/space/articles/117934.aspx#
http://www.wisegeek.com/what-is-a-barycenter.htm
http://www.education.com/science-fair/article/barycenter-balancing-point/
Did you read the selection on the first page? If YES! You can answer these questions.
1. What is our solar system made of?
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2. What is the barycenter?
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3. Where is the barycenter of the solar system?
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4. Why is the barycenter of the solar system very close to the Sun?
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5. Does the moon orbit around earth? Explain.
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6. Does the earth stay in position as the moon revolves around it? Read the whole selection first and
then explain your answer.
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7. Where is the barycenter of the earth and the moon?
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8. Why is the barycenter of the earth and the moon found below the surface of earth? ( 1,710 km or
1062.54 miles below the surface of earth)
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9. What does IAU stands for?
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10. Why is the Earth-Moon System not considered as double planet system?
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11. How do astronomers use the concept of barycenter to locate new planets around stars outside our
Solar system?
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12. What do wobbling stars tell astronomers?
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Barycenter Activity
Environmental Science
Name: _________________________________________ Period: ________ Date: _______________
Essential Question: How is the barycenter affected by the mass of the object?
Binary bodies are two celestial bodies held together by mutual gravitational attraction. In this
project, you will learn how mass affects the location of their barycenter. You will discover the
mathematical relationship between the masses of binary bodies and their distances from their
barycenter. You will prepare a model of the Earth-Moon system and determine the orbit that each body
follows as it orbits the barycenter of the system. You will also discover the location of the barycenter for
most planet-moon systems.
Purpose: To model the barycenter of binary bodies.
Materials:
 one-hole paper punch
 1.25cm -by-7.5cm piece of thick paper, such as a file folder
 2.0 meter or longer cord
 500 g modeling clay
 food scale
 dowel
 meterstick
Procedure:
1. Measure the length of the dowel and mark the mid- point. Label the left end of the dowel as “A”
and the right end as “B”.
A
Length of dowel: __________ cm.
B
Center of the dowel: length of dowel /2 = _________ cm.
2. Use the paper punch to make a hole in each end of the piece of paper.
3. Bend the paper to bring the holes together. Thread one end of the cord through the holes. Tie a
knot to hold the holes together. You have made a paper sling for the dowel.
4. Tie the other end of the cord to a ceiling hook or other supporting object. Adjust the length of the
cord so that the paper sling hangs about chest high.
5. Using the food scale, measure two 200 g pieces. Shape each piece into a ball.
6. Stick one end of the dowel into one of the clay balls to a depth equal to the radius of the ball.
7. Slide the free end of the dowel through the paper sling.
8. Repeat step 5 using the other 200 g clay ball on the other end of the dowel.
Paper Sling
dowel
l
Clay ( A)
Clay ( B)
9. Determine the balancing point by moving the dowel back and forth in the sling until it balances
(see Figure 11.1).
10. Measure the distance from the radius of Clay (A) to the paper sling and the center of the
dowel and record your measures in the data table 1.
11. Measure the distance from the radius of Clay (B) to the paper sling and the center of the
dowel and record your measures in the data table 1.
12. Gently push one of the balls so that the dowel turns. Observe the motion of the clay balls.
13. Prepare a 100 g clay and stick it to the clay on the side A of the dowel.
14. Repeat steps 8-9-11. Record your measures in data table 2.
Data Table 1
Clay
Finding the Barycenter
Distance from the paper sling (
cm.)
Distance from the center of the dowell
( cm.)
200 g (A)
200 g (B)
Data Table 2
Clay
Finding the Barycenter
Distance from the paper sling (
cm.)
Distance from the center of the dowell
( cm.)
200g + 100g (A)
200 g (B)
Answer the following questions:
1. What are the binary bodies?
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2. Where was the paper sling ( cm.) when both ends of the dowel had 200g clay. Explain.
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3. Where was the paper sling ( cm.) when one end had 300g ( 200g + 100 g) clay and the other end had
only 200g clay. Explain.
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4. How is the barycenter or center of gravity affected by the mass of the clays?
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Results
The balancing point is in the center of the dowel, an equal distance from each of the clay balls.
The balls move in a circular path around the sling.
Why?
Binary bodies are two celestial bodies held together by mutual gravitational attraction. Gravity
is a force of attraction between all objects in the universe. Examples of binary bodies are two
stars, a planet and its sun, or a planet and its moon. Binary bodies behave somewhat as if they
were connected by a dowel. Their center of gravity is called the barycenter (the point between
two binary bodies where their mass seems to be concentrated and the point about which they
rotate). If the masses of the binary bodies are equal, the barycenter lies at an equal distance from
each body. Binary bodies revolve (move in a circular path about a point) about their barycenter.
http://www.education.com/science-fair/article/barycenter-balancing-point/