Sun, Moon, and Stars: Astronomy for Beginners · Part II, Ch. VIII · Part 2: Part II: A closer look at the Solar System
21. Saturn and its rings
Goal: Your child can describe Saturn's rings and what they are made of, and knows Saturn is light enough to float.
You'll need
- The book, open to Part II, Chapter VIII
- A paper plate, scissors and a ping-pong ball or small orange (for a ring model)
- A bowl of water and an apple (to show floating)
What's in the book
Saturn, nearly the size of Jupiter but much lighter, wrapped in clouds, with eight moons and three rings: the dusky Crape Ring, a bright middle ring, and a grayish outer ring. The rings are believed to be made of countless small bodies, and the chapter imagines what they would look like from different places on Saturn, including eight-year eclipses in its long winters.
The lesson, step by step
Read together
Read the chapter aloud. Stop at this line and talk about it:
He appears to be made of very light materials — not more than three-quarters as dense as water.
Saturn would float
Drop an apple into a bowl of water. It floats because it is less dense than water. Say: If you had a bathtub big enough, Saturn would float too.
Make a ringed planet
Cut the middle out of a paper plate so a ping-pong ball or small orange fits snugly in the hole. Color three bands on the rim: dusky purple inside, bright white in the middle, gray outside, with a thin gap (the book gives about 1,700 miles) between the bright and the gray.
Tilt it to see the rings wide open, then turn it edge-on and watch them almost vanish. From Earth, Saturn's rings look edge-on every 15 years or so.
What we know now
Saturn has many rings, made of billions of pieces of ice and rock, from specks of dust to chunks as big as a house. They are enormously wide but astonishingly thin.
Its largest moon, Titan, is bigger than Mercury, as the book says. It has thick air and lakes of liquid methane, and a probe landed there in 2005.
Saturn is mostly hydrogen and helium, not a molten ball cooling down. It has well over two hundred known moons. The Cassini spacecraft circled it for 13 years.
Tell it back
Ask your child to describe the view of the rings from Saturn, as the book imagines it: from the equator, from the poles, and in between.
Check questions
How many rings does the book describe, and what colors?
How long is Saturn's winter in each half of the planet?
About how much light does all of Saturn's eight moons together give, compared with our one full moon?
Notice it this week
Check a sky chart to see if Saturn is up. It looks like a steady, pale yellow star. Even a small telescope at a local astronomy club's public night will show its rings; many clubs welcome children.
Answers to the book's problems
Three: the inner dusky or purple Crape Ring, a very bright middle ring, and a grayish outer ring. About fifteen of our years. About one-sixteenth of the light of our full moon.
Worked out for this site from the scan. If a number in your copy differs, trust the book.