Sun, Moon, and Stars: Astronomy for Beginners · Part I, Ch. I · Part 1: Part I: Our family in the sky, and its neighbors
1. The Earth, one of a family
Goal: Your child can explain that the Earth is a round, moving planet, that every star is a sun, and how a planet differs from a star.
You'll need
- The book, open to Part I, Chapter I
- A globe or a ball
- Two small toy figures (or paper cut-outs) and a bit of tape
- A clear evening for star-watching later this week
What's in the book
The first chapter asks what our world is: once thought the flat, fixed center of everything, it is really a round globe that moves, one of a family of worlds called the Solar System. It explains that stars are suns, and that planets are worlds that shine by the Sun's light.
The lesson, step by step
Hook question
SayWhen you sit perfectly still on the couch, are you moving?
Let your child answer, then say you will find out the surprising answer in this book.
Read together
Read the chapter aloud, or take turns by paragraph. It opens like this:
What is this world of ours?
Something very great — and yet something very little.
Pause after the train example and ask if your child has ever felt a parked car or train seem to move when it was really the one next to it.
The big idea in plain words
People long ago thought the Earth was flat and still, with the Sun and stars going round it. In fact the Earth spins and travels, and the Sun and stars only seem to move, just as fields seem to rush past a train window.
Read the book's key sentences together:
A star is a sun. Our sun is nothing more nor less than a star.
so our earth or world is a planet, and planets are worlds.
Try it: which way is up?
Tape one toy figure on the top of the globe and one on the bottom. Each one's head points away from the Earth.
SayThe book says up is always straight away from the Earth, and down is always toward its center. So both of these people are standing the right way up.
Turn the globe slowly so your child sees neither figure is really upside down.
What we know now
The book says no one could tell how far the stars reach. Today we know our Sun is one star among hundreds of billions in a great star-city called the Milky Way galaxy, and that there are billions of other galaxies beyond it.
The book also says the stars keep their places. They do move, but so slowly and so far away that the star patterns barely change in a human lifetime.
Tell it back
Ask your child to tell you, in their own words:
What people used to believe about the Earth, and what we know instead.
Why the Sun looks so much bigger and brighter than the other stars.
How you can tell a planet from a star.
Check questions
What is the family of worlds that the Earth belongs to called?
Is the evening star really a star?
Why do the stars seem to rise and set every night?
Notice it this week
On a clear evening, go outside with an adult and let your eyes get used to the dark for 10 minutes. Look for the seven bright stars of the Great Bear (the Big Dipper) or, in winter, Orion. If you see a very bright point that does not twinkle, it may be a planet.
Afterwards
On another evening, look for a bright 'star' low in the west after sunset. Watch it for a minute: does it twinkle? If not, it is probably Venus or another planet.
Tip
If your sky is cloudy or too bright with city lights, a free planetarium app or website can show tonight's sky. Then look out when it clears.
Answers to the book's problems
The Solar System. No, the evening star (Venus) is a planet that shines by reflected sunlight. Because the Earth turns round once a day; the stars only seem to move. Model narration: People thought the Earth was flat and still in the middle of everything; now we know it is a round globe that spins and travels round the Sun. The Sun looks big because it is much nearer than the other stars. Planets usually do not twinkle, and they shine by the Sun's light, not their own.
Worked out for this site from the scan. If a number in your copy differs, trust the book.