Handbook of Nature-Study · Lesson CCXXXIV · Topic 38: The Sun and the Moon
234. The Moon
Goal: Your child can explain the Moon's phases with a lamp and a ball, keeps a month of Moon drawings, and can describe what a visit to the Moon would be like.
You'll need
- A lamp without a shade (the "Sun")
- A small ball or an apple on a pencil (the "Moon")
- A dark room
- A nature notebook and a pencil (colored pencils if you have them)
- A calendar for a month of Moon-watching
What's in the book
The lesson has a leading thought, a method (watch the Moon for a month, starting at full moon), an experiment with a lamp and two apples to show the phases and eclipses, sixteen observations, and thirteen thinking questions about "the physical geography of the Moon." The book's list of reference books follows.
The lesson, step by step
Safety
A bare light bulb gets hot: don't touch it, and keep paper away. An adult pushes the pencil or skewer into the apple (the book uses a hat pin). Never look at the Sun, even during an eclipse, except through proper eclipse glasses or by a pinhole projector.
The leading thought
The moon always has the same side turned toward us so we do not know what is on the other side. The moon shines by reflected light from the sun, and is always half in light and half in shadow.
Phases with a lamp
Darken the room, turn on the lamp, and let your child be the Earth. Hold the "Moon" at arm's length, a little above your head, and turn slowly in a circle, watching the Moon.
When just opposite the lamp, it shows its whole face lighted turned toward the earth.
Note that the moon always keeps one face toward the earth.
Point out new moon (between you and the lamp), crescent, first quarter, full, third quarter, and the old crescent.
Eclipses
Make an eclipse of the moon by letting the shadow of the earth fall upon it, and an eclipse of the sun by revolving the moon apple between the sun and the earth.
Watch the real Moon
Start at full moon and look whenever you can for a month.
Describe how the moon looks when it is full.
What do you think you see in the moon?
Does the moon rise earlier or later on succeeding nights?
The old moon is seen in the early morning; look for it in the east before school.
Thinking questions
Supposing you could do without air or water and should be able to visit the moon, what would you find to be the color of the sky there?
Would the stars appear to twinkle? Could you see the stars in the daytime?
If you could shout on the moon, how would it sound?
If a man can carry seventy-five pounds on his back here, how much could he carry on the moon?
What we know now
Since this book was written, a spacecraft photographed the far side of the Moon (1959), and twelve astronauts walked on it between 1969 and 1972. They found a black sky even in daytime, no sound, no wind, and footprints that will last for ages. The Moon's sunny ground reaches about 250 degrees Fahrenheit and its night drops to about 200 below zero. And while there is no water to drink or swim in, scientists have found ice hidden in cold, dark craters near the Moon's poles.
Nature notebook
Make a Moon calendar: a circle for each night, shaded to match what you saw, with the date and time. Leave a blank circle for cloudy nights.
Afterwards
Keep the Moon calendar for a whole month, from full moon to full moon.
Answers to the book's problems
Phases: the Moon is always half lit by the Sun; we see more or less of the lit half as it goes around us. The new crescent is seen in the west after sunset; the full moon rises in the east about sunset and sets about sunrise; the old crescent rises before the Sun and is seen in the east in early morning. Moonrise is about 50 minutes later each night. We always see the same side because the Moon turns once on its axis for each trip around the Earth. New moon to new moon takes about 29 1/2 days, so a day on the Moon lasts about two weeks and a night about two weeks. In a year the Moon goes around the Earth a little over 13 times, and we see about 12 1/3 rounds of phases. The old moon disappears because its lit side turns away from us; in an eclipse the Earth's shadow falls on a full moon. On the Moon the sky is black, stars do not twinkle and can be seen by day, and there is no sound because there is no air. At one-sixth the gravity: 75 x 6 = 450 pounds; a 100-yard throw becomes 600 yards; a 135-foot kick becomes 810 feet (in the book's simple reckoning).
Worked out for this site from the scan. If a number in your copy differs, trust the book.