William Allred, Carrie Robledo
Science, Earth Science
Material Type:
High School
  • Barycenter
  • Earth
  • Gas Giants
  • Revolution
  • Rotation
  • Sun
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    Education Standards

    9-12 Earth Science: Beautiful Believable Barycenter

    9-12 Earth Science:  Beautiful Believable Barycenter


    Students will use a model of the solar system to demonstrate the barycenter that exists between the earth and the sun.  

    Instructor Directions

    Engineering Design Process


    Project Description

    Name of ProjectBeautiful Believable Barycenter
    Subject AreaEarth Science
    Targeted StandardsEEn.1.1.1 Explain the Earth’s motion through space, including precession, nutation, the barycenter, and its path about the galaxy.
    Driving Question / Problem / ActivatorExplain barycenter—the point between two objects where they balance each other (For example, it is the center of mass where two or more celestial bodies orbit each other. When a moon orbits a planet, or a planet orbits a star, both bodies are actually orbiting around a point that lies outside the center of the primary (the larger body). For example, the moon does not orbit the exact center of the Earth, but a point on a line between the Earth and the Moon approximately 1,710 km below the surface of the Earth, where their respective masses balance. This is the point about which the Earth and Moon orbit as they travel around the Sun.
    Project SummaryStudents will use a model of the solar system to demonstrate the barycenter that exists between the earth and the sun.  
    Estimated TimeTwo 45min sessions
    Materials / Resources (including link to slideshow if available)Solar system model, ruler, black cloth background, barycenter powerpoint, student worksheet, lesson plan
    TagsBarycenter, revolution, rotation, earth, sun, gas giants

    Project Outline 

    AskExplain the barycenter that is between the sun and the earth using a model of the solar system.
    ImagineGiven the materials, how can you show the barycenter that is between the earth and the sun?  How can the barycenter change location?
    PlanDraw out the Earth-Sun system.  Sketch the location of the barycenter.  
    CreateUse your solar system model and black cloth to demonstrate the location of the barycenter.
    ImproveShare your model with another pair of students and observe their model.  Did you come to the same conclusions?
    Closure / Student ReflectionsReflect on your observations and write a paragraph explaining barycenter using the following terms:  orbit, gas giants, balance point, sun, earth.  Complete the student worksheet.
    Possible Modifications / ExtensionsResearch the orbits of the earth as compared to the gas giants and predict the alignment of the planets.

    Evaluation (Pre/Post)  



    Credits or Modified From

    Barycenter:  The Balancing Point (Source: John Wiley & Sons, Inc. Author: Janice VanCleave, Modified: Patrick McNamara)


    Additional Resources / Help for teaching this lesson



    Sample Pictures / Video





    Teacher Comments of what worked / did not work well

    Having a model to use instead of washers as planets was wonderful!  Students really seemed to get the concept of barycenter.  The model itself is not extremely durable.  If students dropped a planet (which happened a couple of times), the planet’s connector broke off.  I will need to super glue a couple of the models.  Students were able to mark the barycenter with a pencil mark on the sun.  It changed location when they added the gas giants!  Students struggled a little with how to measure how the barycenter had changed, so their data didn’t match what they were seeing, but they seemed to understand the concept that adding mass moved the barycenter towards the larger mass.


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