Overview
In this activity, you will study the effects of gravity on the planets of the Solar System.  First, you need to view movies from the lunar Apollo missions, then calculate your weight on other planets.  Finally, you will propose your weight on newly discovered planets around other stars. 

Materials Needed

• Computer access to one or more AVI-format Apollo Mission movies
• Computer access to the Planetary Weight Calculators (Solar System and Extra-Solar)
• One copy of the Solar System Data Page per group
• One copy of the student answer sheet per student

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 - 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?    Why (give reasons that support your opinion)?

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?    Why?

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 what characteristics cause a planet to have more or less gravity. 

Activity IV - 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!