Why does the Moon not always look the same to us? Sometimes it is a big, bright, circle, but, other times, it is only a tiny sliver, if we can see it at all. The different shapes and sizes of the slivers of the Moon are referred to as its phases, and they change periodically over the course of a lunar month, which is twenty-eight days long. The phases are caused by the relative positions of the Earth, Sun, and Moon at different times during the month.

The Apollo moon landings were one of the most important engineering achievements of the 20th century, and a thorough understanding of the positions of the Earth, Moon, and Sun in space made it possible. Moon Rotation Axis Revolution Waxing Waning Identify the cyclic phases of the Moon. Explain the positioning of the Earth, Moon, and Sun at each phase. Distinguish between waxing and waning. Everyone has gazed at the Moon. Have you ever wondered why it appears to change shape? The week before presenting this lesson, give the students the preliminary assignment of viewing the Moon at night with their parents. Have them record what they see each night in a "Moon Log." If you wish, they can also take pictures. Also, have them flip through magazines and cut out all the pictures they see of the Moon to paste them into the back of their Moon Logs. On the day of the lesson, begin by splitting the students up into groups of 4 or 5. Within the groups, have them share the pictures and observations from their Moon Logs. Ask them why some of the pictures show the Moon as a circle and others show it as a crescent. Give each group a golf ball for the Moon, a softball for the Earth, and a basketball and a flashlight if available for the Sun. This could be done as a demonstration as well. Encourage them to speculate on the positions of each for different phases of the Moon using their prior knowledge and observations from the Moon Logs. Then, open the discussion up to the entire class and discuss their theories. As concepts come up, introduce the appropriate vocabulary. The Earth has only one moon that orbits about it, due to the pull of gravity. The same side of the Moon faces the Earth at all times because the time it takes the Moon to spin once on its axis is the same as the time it takes for the Moon to orbit the Earth once. Because the Moon orbits the Earth and changes its position relative to the Earth and Sun, it appears to have a different shape each night - these are called the phases of the Moon. The Moon shows progressively different phases as it moves along its orbit around the Earth. The phases of the Moon depend on how much of the sunlight can be reflected off the Moon at any one time. In the phase called the new Moon, the face is completely in shadow. About a week later, the Moon is in first quarter, resembling a luminous half-circle; another week later, the full Moon shows its fully lighted surface; a week afterward, in its last quarter, the Moon appears as a half-circle again. The entire cycle is repeated each lunar month. The Moon is full when it is farther away from the Sun than the Earth; it is new when it is closer. When it is more than half-illuminated, it is said to be in gibbous phase. The Moon is said to be waning when it progresses from full to new, and to be waxing as it proceeds again to full. Temperatures on its surface are extreme, ranging from a maximum of 127° C (261° F) at lunar noon to a minimum of -173° C (-279° F) just before lunar dawn. name given to the natural satellite of the Earth, and sometimes applied to the satellites of the other planets in the solar system the different shapes the Moon seems to have in the sky the spinning of an object on its axis This is an imaginary line about which something spins. For the Earth, it is a line extending between the north and south poles. the movement of one object around another object the phase when the entire lit side of the Moon is visible the phase when the entire Moon appears dark because the Sun is lighting the opposite side when only a small lit edge of the Moon can be seen the lit portion of the Moon increasing, progressing from new Moon to full Moon, this is when the Moon is "getting bigger" in the night sky the lit portion of the Moon is decreasing, progressing from full Moon to new Moon, this is when the Moon is "getting smaller" in the night sky A lunar eclipse occurs when the Earth's shadow blocks sunlight from reaching the Moon. At night, the moon appears dark instead of light when it should be a full Moon. A solar eclipse occurs when the Moon passes between the Earth and the Sun blocking sunlight from reaching the Earth. Lunar Lollipops The Moon can be seen from Earth because it reflects the light of the Sun back to Earth. Because the Moon orbits the Earth, it is positioned differently in relation to the Sun each night. Thus, different shapes of the Moon are reflected back to Earth. These are the phases of the Moon. There are eight phases: new Moon, waxing crescent, first quarter, waxing gibbous, full Moon, waning gibbous, last quarter, waning crescent. Tides are caused by the Moon's gravity pulling the ocean and the Earth toward it. The Moon's pull forms a bulge of water on the side of Earth nearest to the Moon as well as on the opposite side of the Earth. These bulges of water move around the Earth to follow the Moon and thus create the tides. The term blue moon is used to express the rarity of an occurrence. A blue moon is when two full Moons occur within one month and thus is very rare. The students should be able to explain why the Moon has different shapes at different times during the month using the appropriate vocabulary. The student should have constructed their own understanding of the concept through using models, drawing pictures, and acting out the phases of the Moon. Lunar Lollipops Clarke, Phillip, Corinne Henderson, Laura Howell, Kirsteen Rogers, and Alastair Smith. 2002. The Usborne Internet-Linked Science Encyclopedia, Usborne Publishing Ltd, London. Graham, Ian. The Best Book of the Moon. Kingfisher: New York. Simon, Seymour. The Moon. Simon & Schuster: New York.