Sun, Moon, and Stars: Astronomy for Beginners · Part II, Ch. VI, part 2 · Part 2: Part II: A closer look at the Solar System
19. Mars, the red planet
Goal: Your child can tell what the book believed about Mars and what spacecraft have since found there.
You'll need
- The book, open to the Mars pages near the end of Part II, Chapter VI
- Paper and red, brown and white crayons
- The planet chart
What's in the book
The last pages of the chapter are about Mars: its two tiny moons, Deimos and Phobos, its lightness, its air, its reddish and dark markings (then thought to be continents and seas), its clouds, and its white polar caps that shrink and grow with the seasons.
The lesson, step by step
Read together
Read the Mars pages aloud. Enjoy the book's idea of a traveler who could go everywhere on Mars by land or by water.
Watch the ice caps
Read the part about the polar caps again. Draw Mars twice: once with a big white cap at the top and a small one at the bottom, once the other way round.
This is exactly what takes place in the summers and winters of our north and south poles.
What we know now
Mars has no seas or canals. The dark markings are darker rock and dust; great dust storms sometimes wrap the whole planet, which helps explain the changes the book mentions.
The polar caps are real ice, partly frozen water and partly frozen carbon dioxide (dry ice), and they do grow and shrink with the seasons, just as the book says.
Rovers have driven across Mars, and a small helicopter has flown there. They found dry riverbeds and rocks that formed in water, so Mars had lakes and rivers long ago. Its air today is very thin and mostly carbon dioxide.
Phobos and Deimos, the moons the book mentions, are small lumpy rocks only a few miles across.
Tell it back
Ask your child to tell you two things the book got right about Mars and two things we have learned since.
Check questions
What are the names of Mars' two moons?
Why does the book think Mars has seasons?
Why is it easier to study Mars than Venus from Earth?
Notice it this week
Ask a grown-up to help you check a sky chart or app to see whether Mars is in the evening sky. It looks like a steady orange-red 'star'.
Answers to the book's problems
Deimos and Phobos. Because its white polar caps shrink when that pole is turned toward the Sun and grow when it is turned away, just like seasons on Earth. Because Mars is outside our orbit, so when it is nearest it shows us its sunlit face, while Venus at its nearest turns its dark side to us (and Venus is covered in clouds).
Worked out for this site from the scan. If a number in your copy differs, trust the book.