Sun, Moon, and Stars: Astronomy for Beginners · Part I, Ch. V · Part 1: Part I: Our family in the sky, and its neighbors
6. The giant planets, and a model you can walk
Goal: Your child can name the four outer planets in order, and has paced out a scale model that shows how huge the distances are.
You'll need
- The book, open to Part I, Chapter V
- A ball about 8 inches across (a playground ball) for the Sun
- Pins, a peppercorn or two, a few beads, two hazelnuts or large marbles
- Index cards and a marker for labels
- A long open space: a park, a beach, or a quiet road with an adult
What's in the book
The chapter travels out past the asteroids to Jupiter, Saturn, Uranus and Neptune: their sizes, speeds, long years, moons and Saturn's rings. It ends with two scale models (from Proctor and Herschel): one shrinks the Earth to three inches, the other puts a two-foot Sun at the center with Neptune more than a mile away.
The lesson, step by step
Read together
Read the chapter aloud. Pause at each new planet to add it to the planet chart from last time.
Enjoy the book's birthday jokes: a 37-year-old would be 3 on Jupiter, and a 60-year-old would just have had a second birthday on Saturn.
The book's two-foot Sun
Read the last pages again slowly. With a two-foot Sun, the Earth is a pea 215 feet away, Jupiter an orange nearly a quarter of a mile off, and Neptune a plum about a mile and a quarter away.
These proportions as to size and distance, if carefully studied, will serve to give a clearer idea of the Solar System as a whole than learning a long list of numbers would do.
Walk a smaller model
Use an 8-inch ball for the Sun, one third the size of the book's. Then take big steps of about a yard each and place a labeled card for each planet:
Mercury (a grain of sand or pin-head): 9 steps from the Sun.
Venus and Earth (each a pin-head): 17 and 24 steps.
Mars (a smaller pin-head): 36 steps.
Jupiter (a large marble or hazelnut): 124 steps.
Saturn (a slightly smaller hazelnut): 229 steps.
Uranus and Neptune (each a peppercorn): 458 and 718 steps.
Most families stop at Jupiter or Saturn and just point toward the rest. That is fine: the point is how empty space is.
Look back at the Sun
From the Earth card, look back at the 8-inch ball. Say: That is how big the Sun looks from Earth compared with the distance. Now look from Jupiter.
What we know now
The book's eight planets are the same eight we count today. Pluto, found in 1930, is now called a dwarf planet.
Moons: the book gives Jupiter five, Saturn eight, Uranus four, Neptune one. We now know Jupiter has about a hundred, Saturn well over two hundred, Uranus more than two dozen and Neptune more than a dozen, and more small ones are still being found.
Saturn has many rings, not three, made of countless pieces of ice and rock. Jupiter, Uranus and Neptune have thin rings too.
Jupiter and Saturn are giant balls of gas and liquid with no solid surface to stand on. Neptune is a little narrower than Uranus but heavier.
Tell it back
Ask your child to name all eight planets in order from the Sun and say which is biggest, which has the famous rings, and which takes longest to go round the Sun.
Check questions
How many Earths would fit inside Jupiter, according to the book?
How long is a day on Jupiter?
How long is Neptune's year?
Afterwards
Make up a sentence to remember the order, one word per planet: for example, 'My Very Excellent Mother Just Served Us Nachos.'
Tip
If space is short, walk only to Mars in the backyard and use a map app to find a landmark about the right distance away for Jupiter (about 124 yards) and Neptune (about 718 yards).
Answers to the book's problems
More than twelve hundred. About ten hours. About 165 of our years. Order: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. Jupiter is biggest, Saturn has the famous rings, and Neptune takes longest.
Worked out for this site from the scan. If a number in your copy differs, trust the book.