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Project Summary

Difficulty	3
Time required	Very Short (a day or less)
Prerequisites	None
Material Availability	Readily available
Cost	Very Low (under $20)
Safety	No hazards

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Abstract

Objective

In this experiment you will investigate how the phases of the moon correspond to the changing tides.

Introduction

You may have heard that the tide comes in and the tides goes out, but in fact a tide is the vertical movement of water and only goes up and down. Current is the horizontal or sideways flow of water. The current floods in which makes the tide rise and ebbs out which makes the tide fall. A tide is the rise and fall of water caused by gravitational forces of the moon and sun on the oceans of the earth.

How do the movements of the sun and the moon affect tide? The gravitational pull of the moon tugs on the surface of the ocean until its surface mounds up and outward in the direction of the moon. When the mound of water has reached its highest point it is called high tide. On the opposite side of the earth from the moon, the centrifugal force caused by the earth's rotation produces another mound of water and high tide. Between these two high tides are two flat areas on the surface of the ocean which are the low tides.

Each day there are two high tides and two low tides. The time between high and low tide is a little over 6 hours and the entire tidal cycle repeats itself four times each day. The regularity of the tides corresponds to the regular orbit of the moon around the earth and the rotation of the earth as it orbits around the sun.

Depending upon the position of the moon relative to the earth and sun, a moon can have different phases. The phases of the moon are also very regular, and have been used for thousands of years to keep track of time using the lunar calendar. In addition to the daily movements of the moon, these monthly lunar cycles can also impact the tides.

In this experiment, you will compare the heights of high and low tide during the full moon and the new moon to determine if the phases of the moon affect the tides. You will use data that has been generated by a computer database to predict the timing and height of the tides. You will also use the lunar calendar to compare your tidal data to the lunar cycle.

Terms, Concepts and Questions to Start Background Research

To do this type of experiment you should know what the following terms mean. Have an adult help you search the internet, or take you to your local library to find out more!

• new moon
• full moon
• phase of the moon
• high tide
• low tide
• gravitational force
• orbit
• rotation of the earth

• When are tides high and low?
• Is there a relationship between the phase of the moon and position of the tide?
• Are tides high or low during a full moon? A new moon?

Bibliography

• 2000. "Boat Safe Kids! How Does the Moon Affect Tides?" Stuart, FL: Nautical Know How, Inc. [1/20/06]
  http://www.boatsafe.com/kids/tides.htm
• 2005. "The Phases of the Moon." U.S. Naval Observatory Astronomical Applications Dept., Washington, D.C. [1/20/06]
  http://aa.usno.navy.mil/data/docs/MoonPhase.html
• 2005. "Tides Online." NOAA, Washington, D.C. [1/20/06]
  http://tidesonline.nos.noaa.gov/
• Bonnet, R.L. and Keen, G.D. 1992. Space and Astronomy: 49 Science Fair Projects NewYork, NY: McGraw-Hill Inc.

Materials and Equipment

• computer
• Internet
• printer
• 2 highlighters in different colors
• graph paper

Experimental Procedure

1. First, get on your computer, connect to the Internet and open up your web browser.
2. Type the URL, or Web address, for the U.S. Naval Observatory "Phases of the Moon" website into the navigation bar: http://aa.usno.navy.mil/data/docs/MoonPhase.html
3. You will see data for phases of the moon from years 2000–2010. Scroll down to choose the data for the year you want to study (2005). You need to print this part of the page for a reference:

4. Using a highlighter, mark the dates for the full moon in pink and the new moon in yellow. This is the data you will use for your experiment, the other data you will need to ignore.
5. Next, type the URL, or Web address, for the NOAA "Water Level and Tidal Current Predictions" website into the navigation bar: http://www.co-ops.nos.noaa.gov/tide_pred.html
6. Scroll down and select a year to match your data for the phase of the moon (2005).
7. This will bring you to the homepage for the "Water Level and Tidal Predictions" for that year. Scroll down and choose the state you are interested in. You will then need to choose the region within the state, and then a particular naval station. When you see the naval station you are interested in, click on the "Predictions" link for that station.
8. This will give you a long list of the predicted height of the tide at your chosen location for that year. You will also want to print this page for your reference:

9. Each row of data on this page will list one day of the year, followed by the time (in local standard time, LST), height (in feet, ft) and peak (either high or low, H or L) of each of the 4 tides of the day. There should be 2 low tides and 2 high tides in alternation each day, either H L H L or L H L H.
10. The good news is that you will need to ignore most of the data! The bad news is that you will have to find the right data. To do this, you will need to use your moon phase data for the dates of the full moon and the new moon for the year.
11. Using a highlighter, mark each date that matches with a full moon in pink and the new moon in yellow. This will help differentiate between the two phases and make them easier to see. For one year, there will be 12 new moons and 11 full moons, so you should have highlighted 23 days total from your data.
12. Now that you have your data chosen and organized, you will want to make a graph. Using your graph paper, set up your graph like this:

13. Now choose one color to represent the full moon, and another color to represent the new moon. Using the correct color, place a dot on the graph of the high and low tides of the day. You should have two dots for the high tide, and two dots for the low tide for each day. If the low tide goes below zero, you can draw your graph to include negative numbers on the Y-axis.
14. When you are finished you can look at and analyze your results. Is there a difference between the high and low tides during a full moon compared to a new moon?
15. You might also want to make a bar graph to represent your data. Try calculating the difference between the high and low tides by subtracting, then you can make a bar graph to represent your data. Is the difference between high and low tide the same or different for new moons and full moons?

Variations

• This experiment uses computer generated data that has been predicted using mathematical formulas. You can make your own natural observations to verify the accuracy of the predicted data. If you live near a marina, see if they have a tide guage that you can use to make readings. You can also use a piece of wood secured to a bulkhead to track the height of the tide each day. To track the changes in the moon keep a lunar logbook. Go outside each evening to draw the changes in the moon's appearance. How close do your recorded measurements come to the predicted data? Are computer generated models useful for this type of astrological data gathering?
• In this experiment tide height was tracked for a year during the new moon and full moon. How do the other phases of the moon affect the tide? You can add to the complexity of the above experiment by adding in the data from the first quarter and last quarter lunar phases. You can also Do a different experiment by comparing the daily tide height and lunar phase for a full lunar month. Can you observe a cycle or pattern?
• The lunar calendar was very important during the early days of agriculture. We call the fall moon a "harvest moon" because the giant red colored moon coincides with the time of year when crops are harvested. Does the moon have any effect on plants and agriculture? Do an experiment to test the effect of lunar phase on the germination of beans by planting beans during different lunar phases. Are seedlings more successful during a particular lunar phase? Do an experiment to test if plants need moonlight in thier leaves to stay healthy by covering a plant in the evening, shielding it from moonlight. Do plants need the moonlight to stay healthy?

• For more science project ideas in this area of science, see Astronomy Project Ideas.

Credits

Sara Agee, Ph.D., Science Buddies

Last edit date: 2006-02-15 15:34:29

Career Focus

If you like this project, you might enjoy exploring careers in Astronomy.

Astronomer Astronomers think big! They want to understand the entire universe—the nature of the Sun, Moon, planets, stars, galaxies, and everything in between. An astronomer's work can be pure science—gathering and analyzing data from instruments and creating theories about the nature of cosmic objects—or the work can be applied to practical problems in space flight and navigation, or satellite communications.

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