Students in the middle level solar system activity will study the effects of gravity on the planets of the Solar System. They will view movies from the lunar Apollo missions, calculate their own weight on other planets, and propose what they might weigh on newly discovered planets around other stars. 

By completing this activity, the learner will: 

• view on-line movies from the Apollo Moon landings
• determine their own weight on other planets
• investigate the variables that influence weight
• predict their own weight on newly discovered planets
• evaluate gravity hypotheses of other students

National Mathematics Education Standards

Materials and Technology 

Science Background Information

Activity 1: Exploration - By watching short on-line movies, students decide if there is any gravity on the Moon.

Activity 2: Determine what variables influence a planet's gravitational strength.

Activity 3: Discover how much you weigh on various planets.

Activity 4: Prove or disprove various hypotheses about the causes of a planet's gravtitational strength and write a paragraph that explains what characteristics cause a planet to have more or less gravity.

Activity 5: Predict what you would weigh on newly discovered planets and check your predictions.

Is there any gravity on the Moon?  How could you find out?  As a first step, watch one or more of the following movies of US astronauts working on the Moon.  Most are in AVI format and are black & white as they were made between 1967 and 1971. 

Activity II - Concept Introduction: How much do you weigh on distant planets?

Clearly, the above movies show that the Moon does in fact have gravity--but less gravity than Earth does.  So which planet characteristics cause a planet to have more or less gravity?  Consider the following variables--presence of an atmosphere, planet diameter, planet mass, planet temperature, and/or distance from the Sun.  Which do you think is most important in determining a planet's gravitational strength? 
Activity III - Discover how much you weigh.  To investigate your hypothesis, find out how much you weigh on other planets using the CERES Solar System Weight Calculator.  Then use the Solar System Data Table or books from the school library to see which planets have properties that might affect your weight on other planets.  You might find it helpful to make a comparison chart. 

Now, which planetary property seems to cause you to weigh more or less on other planets? 

Activity IV - Concept Introduction: What causes a planet to have gravity?

Consider each of the following hypotheses about what causes you to weigh more or less on other planets.  Use the Weight Calculator and the Solar System Data Table to prove or disprove the proposed hypotheses. 

Aaron's Hypothesis	Planets with thin or no atmosphere have little or no gravity--like Mercury.	Why do you agree or disagree?  Give examples from your data.
Pat's Hypothesis	Planets that are cold have only a small amount of gravity--like Saturn.	Why do you agree or disagree?  Give examples from your data.
Chris' Hypothesis	Planets that are massive and have the largest diameters have the most gravity.	Why do you agree or disagree?  Give examples from your data.
Kesh's Hypothesis	Planets that have thick atmospheres and are farther from the Sun have the most gravity.	Why do you agree or disagree?  Give examples from your data.

Write a brief paragraph that explains in detail which properties cause a planet to have more or less gravity?  Which properties do not impact gravity?

Activity V - Concept Application: How much would you weigh on the newly discovered planets?

In recent years, astronomers have found very large planets around stars far from our solar system.  Most of these stars are very large and very massive.  How much do you think you would weigh on these newly discovered planets?  Try out your prediction using the CERES Extra-solar Planet Weight Calculator.  Don't forget to check out the most recent list of planets discovered! 

Assessment