Activities: The Moon is lit and unlit too

Transcription

1 Activities: The Moon is lit and unlit too Key objectives: This activity aims to help student to: Identify the different phases of the Moon Know that the Moon does not produce its own light, but reflects light from the Sun. Be aware that the Moon moves around the Earth once a month. Know to look for the Moon in the day and night sky. Moon myths Background information A month is the time taken for the Moon to make one apparent orbit of the Earth, travelling at an average speed of 3,680 km/h. The Moon rotates on its axis as it orbits the Earth, completing one rotation every 27.3 days. This is the same amount of time taken for the Moon to orbit the Earth; therefore we only ever see one side of the Moon from Earth. The other side is known as the far side. It was originally called the dark side, however this is misleading, as it is not always dark. For example, when we see a New Moon, the far side is lit and the side we see (the near side) is dark. The far side was first seen in December 1968, when astronauts travelling on Apollo 8 circled the Moon. What you need Copies of worksheets: Lit and unlit and Moon watch Myths from different cultures explaining phases of the Moon What to do 1. Read the worksheet Lit and unlit, in which Oscar is concerned about the Moon appearing to change shape. 2. Discuss with the children the observations they have made using their Moon watch worksheet (see What do Toys do at night activity). Ask them to write what their soft toy has noticed onto the Lit and unlit worksheet. 3. Read myths from various cultures which explain the day, night and phases of the Moon. Discuss any similarities/differences between the stories. Why aren t they factual? Ask the children to write their own myth. 33

2 Phases of the Moon Background information Research has shown that children will get confused if you draw the Moon and unlit area on a blackboard using white chalk. They will not be sure which area the blackboard or the shaded white chalk is meant to represent the unlit part of the Moon. Use a whiteboard or large sheet of paper if you are illustrating the phases in this way. Solar eclipses only occur during the time of the New Moon when the Moon lies between the Sun and the Earth. Lunar eclipses only occur during the time of Full Moon when the Earth lies between the Sun and the Moon. Eclipses are rare because the Moon's orbit is tilted by 5 compared to the Earth's orbit around the Sun. Therefore, during most months, the Moon passes either above or below the Sun as seen from Earth. When the Moon is thin, from Last Quarter through New Moon to First Quarter, it is called a crescent Moon. When the Moon is fat, from First Quarter through Full Moon to Last Quarter it is called a gibbous Moon. When the Moon appears to be growing from New Moon through First Quarter to Full Moon we say it is waxing. When the Moon appears to be shrinking from Full Moon through Last Quarter to New Moon we say it is waning. It takes about 25 hours between one Moon rise and the next. This means that the Moon rises about one hour later each day. For best times to see the different phases of the Moon, see the table below. Phase Moon rise Moon set Best daytime view Best night time view New Sunrise Sunset In daytime sky but Not in night sky difficult to see (none of the lit side is facing us) First Quarter Midday Midnight Afternoon in the eastern sky Evening in the western sky Full Sunset Sunrise Not in daytime sky In night sky (appears in the east at sunset) Last Quarter Midnight Midday Morning in the western sky Early morning in eastern sky 34

3 What you need Shadeless lamp with bright globe Access to a darkened room 5cm polystyrene foam balls Pencils What to do 1. Skewer the foam balls onto pencils so that the pencils can act as handles. Place the lamp in the centre of the darkened room with the children in a circle around it. (With large classes you may need to have only half the class participate at a time.) 2. Allow time for free play, with the children holding the ball and turning in different positions to notice the lit and unlit areas of the ball. 3. Have each child hold their foam ball in their right hand. Ask them to extend their arm in front of them so that the ball comes between their eyes and the lamp. 4. Explain that the light globe represents the Sun, the ball represents the Moon and they are the Earth. The view they get models what they see in the sky. Note that the ball is reflecting light from the lamp and that it does not produce its own light. 5. In the starting position the Moon blocks the Sun. (This is actually demonstrating a total solar eclipse which is very rare for any given location on Earth.) Usually the Moon passes above or below the Sun as viewed from Earth so have the children move their Moon up a bit so that they can also see the Sun. As they look up at their Moon they will only see its unlit side. This phase is called New Moon (like no Moon ). 6. The children should start to sweep their right arm back in a clockwise direction. By the 45 position they should see the left hand edge of the Moon illuminated as a crescent. The crescent will start out very thin and fatten up as the Moon moves around the Earth. When their arms are out by their side, the students will see the left half of the Moon illuminated. This phase is called First Quarter. As they continue to move their arm around behind them the Moon goes into its gibbous phase. 7. Ask the children to turn their heads to view the Moon with their arm behind their back. The section of the Moon facing Earth is fully illuminated (unless the student's head is causing a lunar eclipse). This is called the Full Moon. 35

4 8. Ask the students to switch the pencil and Moon to their left hand. They should hold the Moon behind them in the Full Moon position and move their arm forward continuing the clockwise motion. They will view a gibbous Moon with the right portion of the Moon illuminated. 9. Once their arm is straight out to their left they will view the Last Quarter Moon with the right side of the Moon illuminated. Continuing to move their arms in a clockwise direction, the children will then see a thinning crescent and a return to New Moon. 10.Throughout the demonstration, point out that half the Moon is illuminated at all times and that it s just our view of the Moon that changes as it moves around the Earth. Note: For smaller children this activity can be done by having the students turn around with their Moon so that it is easier for them to see the phases. This diagram shows the apparent rotation of the Moon around the Earth, as viewed from space. The inner ring of diagrammatic Moons shows that the side of the Moon facing the Sun is always lit. The grey arrows show our direction of sight. When looking at the Moon from the Earth, what we see is shown by the outer ring of Moon photographs. For example, when we see a New Moon, our view is of the unlit side of the Moon and when we see a last Quarter Moon, we see the right hand side lit and the left hand side unlit. 36

5 Moon through my window Background information As seen from the Southern Hemisphere, the left portion of the Moon is illuminated at First Quarter and the right side of the Moon at Last Quarter. At the equator, however, the top portion of the Moon is illuminated at First Quarter and the bottom portion at Last Quarter. In the Northern Hemisphere the right portion of the Moon is illuminated at First Quarter and the left side at Last Quarter, (exactly opposite to how we see the phases of the Moon). This difference occurs because the Earth is spherical. When we move from one hemisphere to the other, the positions of objects in the sky appear to rotate. It happens with all things in the sky, which is why those constellations named in the Northern Hemisphere (e.g. Orion) appear upside down to us in the South. What you need Copies of the two Moon through my window worksheets Scissors Butterfly clips What to do 1. Copy the two Moon through my window worksheets. For young children, make a starting hole so they can easily cut out the window pane. 2. Ask the children to cut out the window pane on the first worksheet and the Moon phase circle on the second worksheet. 3. Label each Moon phase. 4. Place the Moon phase circle in position behind the window pane and use a butterfly clip to fasten it. 5. Move the circle around to view the changing phases of the Moon. 6. Read Oscar s explanation for the changing phases. Extension Activities Act out some myths used to explain the phases of the Moon or day/night cycle. Learn the names of the months and the numbers of days in each. Investigate how each month got its name. Compare the size of the Earth and Moon and the distance between them. If you use a globe of the Earth with a 30cm diameter, a tennis ball of approximately 6cm diameter makes a good Moon. The Moon is about 30 Earth diameters away: in this case approximately 9 metres. The Sun is 450 Earth/Moon units away. In this case 450 x 9m = 4050 metres away. 37

6 Worksheet Photocopy this page. Lit and unlit Toys, I ve got another question. I think it has something to do with the Sun again, barked Oscar. What is it? asked Tina. Well, the Moon looked like a half circle when the cow jumped over it. Now look at it! It s a full circle. It looks a bit like a face, giggled Nellie. I ve noticed 38

7 Worksheet Photocopy this page. Moon through my window I understand now, said Oscar. Half of the Moon facing the Sun is always lit. The half facing away from the Sun is unlit. The Moon moves around the Earth and the view we see changes depending on how much of the lit side is facing the Earth. 39

8 Worksheet Photocopy this page. Moon through my window 40

9 Worksheet: Photocopy this page. Moon watch Look for the Moon during the day and night. Write down the time that you see it. What part of the sky was the Moon in when you saw it? Up high in the sky or low down? Could you see the Sun too? (Remember Never look directly at the Sun as it can hurt your eyes). Colour the picture of the Moon so it looks like the view you see. Monday Tuesday Wednesday Thursday Friday Saturday Sunday