Phases of the Moon and Tides    R. Briody

                       STUDENT HANDOUT FOR DATA COLLECTION

  As we have already discussed, the tide comes in and the tide goes out.  What really happens is that the water goes up and  down.  Current is the sideways flow of water.  The current occurs when the water flows in and out during high and low tide.  The tide is the rise and fall of the water.  This is caused by the gravitational pull of the moon and the sun on the earths’ oceans.  
  The gravitational pull of the moon causes the water in the ocean to rise up in a mound toward the moon.  This is called a high tide.  Another mound forms on the opposite side of the earth.  This is caused by the spinning earths’ centrifugal force.  There are two high tides on the earth at any given time. There are two flat areas between the high tides.  These are called low tides.
   The earth rotates below the two high tides and low tides.  Because the earth rotates once every twenty-four hours there is about six hours between each high tide and low tide.  Because the moon is orbiting the earth from west to east, very slowly, there is a fifty minute delay in the tide (and moonrise ) each day.
  When the earth, moon an the sun line up, as in a Full Moon or New Moon, the gravitational pull will be greater on the oceans and the difference between   the high and low tide will be greater.  When the earth, moon and sun are at ninety degree angles, as in the First and Last Quarter, the gravitational pull will be less and the difference between the high and low tide will be less.
  Because of the positions (angles) of the earth, moon and sun, the moon will appear to change shape each month.  These are called phases.  They are very 
regular  and predictable each month. (The word month came from thee word moonth meaning the period of the four phases of the moon.)   These phases of the moon affect the tides in a regular and predictable pattern.

  PROCEDURE

   In this experiment we will plot the heights of the high and low tides during the Full Moon and Last Quarter Moon for the year 2007.  We will use data from a computer database to find the dates of these moon phases and the height of these tides.

                               STEPS FOR DATA ANALYSIS

-Connect to the Internet.
-Go to http://aa.usno.navy.mil/AAmap
-Go to data for phases of the moon from the years 2000-2010.  Scroll down 
 and choose the year 2007.
-Record the dates for the Full Moon and the Last Quarter Moon for each
 month.

-Next, go to http://www.tidesandcurrents.noaa.gov
-Scroll down and select the year 2007 to match your data.  This will bring  
 you to the homepage for the “Water Level and Tidal Predictions” for that
 year,
-Scroll down and choose “Massachusetts.”
-Next scroll down to “Steep Brook, Taunton River.”
-Click “Predictions” at the right end of the line.
  This gives you a list of the height of the tides for each day, for each moon
 phase, for each month of 2007.

  Use the moon phase data chart to find the date pf the Full Moon and the 
 Last Quarter Moon for each month of 2007.
  -Record the height of the high tide and low tide for each Full Moon and
 Last Quarter Moon for the twelve months of 2007.

TERMS, CONCEPTS AND QUESTIONS

  To do this exercise you should know the following terms:  Full Moon, Last Quarter Moon., Phases of the Moon, high tide, low tide, gravitational force, orbit rotation of earth.

-When are tides high and low?
-Is there a relationship between the phase of the moon and the position of the tide?
-What is the effect of a Full Moon on high and low tides?
-What is the effect of a Last Quarter Moon on high and low tides?