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Learning Lesson: Moonlight Serenade |
| OBJECTIVE |
Observe how different angles between the sun, earth and moon affect the phases of the moon we see each month. |
| OVERVIEW |
Students, acting as the earth, will see differences in light and dark sides of their "moon" they hold. |
| TOTAL TIME |
10 minutes |
| SUPPLIES |
Table lamp (or another light source) for class. (A clear light bulb will work better than a frosted bulb.)
Per pair of students: pencil, white styrofoam ball (approximately two to three inches in diameter).
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| PRINTED/AV MATERIAL |
Observation form (pdf) |
| TEACHER PREPARATION |
A room that can be darkened. |
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| Background |
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The moon orbits the earth approximately every 27¼ days. The moon reflects sunlight on to the earth. It is over a quarter of Earth's diameter which is much larger in comparison with its planet than any other in the solar system.
However, despite its size, gravity on the moon is about a sixth of that on the earth. For example, an object weighing 100 pounds on the earth would weight only 17 pounds on the moon.
Because there is no atmosphere on the moon, there is no weather systems. The lack of atmosphere also means there are large temperature swings from the sunlite side to the dark side. On the sunlite side, temperatures are as high as 250°F (>100°C) falling to as low as -250°F (-173°C) on the dark side.
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| Procedure |
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- Divide the students into pair and distribute one observation form to each student.
- Place a lamp on a table or desk and remove the shade. Turn the lamp on.
- Stick the styrofoam ball on the pencil.
- Darken the room.
- Have one of the pair of students hold the ball, by the pencil, at arms length blocking out the light from the lamp. Explain they represent the earth, the ball is the moon, and the lamp is the sun.
- Comparing the light and dark side of the ball, on the observation form, under the "View from Earth" column, have that person draw/shade what their "moon" looks like. Have the student label this as "New Moon".
- Have the other person mark the location of the moon relative to the earth and sun on the dotted line (representing the Moon's orbit) under the "Position in Space" column.
- Have the student holding the "Moon" rotate 45° counter-clockwise. Repeat steps 6 and 7. Label this as "Waxing Crescent".
- Rotate another 45°. Repeat steps 6 and 7. Label this as "First Quarter".
- Repeat steps 6 and 7 for each additional 45°, labeling them as "Waxing Gibbous", "Full Moon", "Waning Gibbous", "Last Quarter", and "Waning Crescent" respectfully.
- Have the students switch positions and repeat the process again.
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| Discussion |
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Each student will see their "moon" from two vantages points; from earth's viewpoint and from "space". They should quickly observe that the position of the moon, relative to the earth and sun, is the reason for the various phases of the moon.
They will also observer to phenomena at the new and full moon positions. At "new moon", when the moon is between the earth and sun, the moon will block the sun's light, called a solar eclipse. At "full moon", the earth blocks light from reaching the moon causing the moon to be darkened. This is called a lunar eclipse.
You can explain that since the moon's orbit is inclined to the earth's equator that these eclipses typically occur just twice a year.
Also, as the moon orbits the earth, the moons tidal pull also moves around the earth. As a result, the difference between the height and high and low tides changes each day. When the moon, earth and sun are inline (twice a month), the tidal pull by the moon and sun are at their greatest producing "Spring Tides", where the difference between the daily high and low tide are at their greatest.
When the earth, moon and sun are at right angles to each other (also twice a month), the difference between the daily high and low tides are their least, called "Neap Tides".
The "Spring Tide or Neap Tide" wheel (above right) can be print and cut-out to help illustrate how the orbit of the moon affects the spring and neap tides. |
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| Back: Tides |
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National Weather Service
Southern Region Headquarters
819 Taylor Street
Fort Worth, Texas 76102 |
www.srh.weather.gov
Updated: March 29, 2006 |
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