Universe Cycle - Earth (2)
Pre Lab 

   
OBJECTIVES:
  • Comparing the Earth and the Moon.
  • Discovering why the Moon changes at night.
VOCABULARY:
  • atmosphere
  • hydrosphere
  • planet
MATERIALS:

Students trace the phases of the Moon.

BACKGROUND:

The Moon is the Earth's satellite. Students are familiar with the Moon because they see it at night. However the Moon changes its shape from night to night. There also seems to be a cycle to these changes. Every month the Moon goes through a cycle of phases from new (cannot see it) to full (can fully see.) It takes 27.3 days for the Moon to complete one orbit of the Earth. The Earth also moves relative to the Sun at the same time the Moon is revolving around the Earth, so the Moon must complete more than one orbit to return to the same phase as seen from Earth. The time that the Moon takes to complete one cycle or "phases of the Moon" is 29.5 days.

Each spot on the Moon is subjected to two weeks of day light, during which the surface temperature reaches about 100 degrees centigrade (boiling point). The next two weeks are night and temperatures fall to -170 C. The Moon has no atmosphere. There is evidence that there is water ice in some deep craters near the Moon's south pole which are permanently shaded.

There are two primary types of terrain on the Moon: the heavily cratered and very old highlands and the relatively smooth and younger mare (or maria). The mare (which comprise about 16% of the Moon's surface) are huge impact craters that were later flooded by molten lava. Most of the surface is covered with regolith, a mixture of fine dust and rocky debris produced by meteor impacts. For some unknown reason, the mare are concentrated on the near side.

PROCEDURE:


Not quite a full moon.

  1. Read the book The Moon Seems to Change to the class. The book attempts to show the students why the Moon changes its shape. The book includes a demonstration using a flashlight and an orange, showing the different positions as shown on the student’s worksheet. You may want to try this with the class, either individually or as a group. This visualization helps students to understand the movements involved with the phases of the Moon.
     
  2. Have the students complete the worksheet. Have them color the bright part of the Moon in yellow, as well as the sunlight arrows. Have them draw arrows to indicate the direction of the Moon's revolution around the Earth. The arrows should go counterclockwise. If the students seem to grasp the concept, you can also have them draw the Moon’s rotational axis and direction of spin (also counterclockwise).
     
  3. If you have internet access you can view all the phases of the Moon from 1800 to 2199 AD, even the day you do this lesson!

    http://tycho.usno.navy.mil/vphase.html

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