Sun, Moon, and Stars: Astronomy for Beginners · Part II, Ch. III · Part 2: Part II: A closer look at the Solar System
15. Yet more about the Sun: prominences, the corona, and the Sun's pull
Goal: Your child can describe a solar prominence and the corona, and compare how much they would weigh on the Sun, the Earth and the Moon.
You'll need
- The book, open to Part II, Chapter III
- Paper and pencil, or a calculator
- A bathroom scale (optional)
- Black paper and white and red crayons or pastels
What's in the book
The chapter describes a giant eruption Professor Young watched in 1871 at the edge of the Sun, the shapes and heights of the red prominences, and the many descriptions of the corona seen in eclipses. It ends with the Sun's size, density and enormous pull.
The lesson, step by step
Read together
Read the chapter aloud. At the story of Professor Young, pause: he was called away for half an hour, and when he came back the great cloud of fire had been blown to shreds.
SayHe watched it with a special instrument, the spectroscope, not with his bare eyes.
How big are the flames?
Read:
The earth, Venus, Mars, and Mercury would lie like little toy-balls at its foot.
Draw a curved Sun edge on black paper, a red prominence rising from it, and a tiny dot for the Earth at its foot.
The corona
Read a few of the book's descriptions of the corona aloud. Let your child add a soft white crown with streamers around the Sun picture, in the style they like best.
Weigh yourself on other worlds
The book says a person would be crushed by their own weight on the Sun and could leap over a house on the Moon. Use real numbers: on the Sun's surface you would weigh about 28 times as much as on Earth; on the Moon, about one sixth.
Take your child's weight. Work out their 'Sun weight' (times 28) and 'Moon weight' (divided by 6).
What we know now
The book says knowledge of the corona was 'in its infancy'. We now know it is the Sun's very thin, extremely hot outer air, over a million degrees, and a spacecraft, the Parker Solar Probe, has flown through it.
The eruption Young saw is what scientists now call a coronal mass ejection: a huge cloud of the Sun's gas thrown out into space.
The book is right that the Earth is about four times as dense as the Sun.
Tell it back
Ask your child to tell Professor Young's story as if they were the professor writing in a diary that evening.
Check questions
What gas are the prominences mostly made of?
When can people see the corona without special instruments?
Why is the pull of gravity so strong on the Sun?
Afterwards
Hang the black-paper Sun picture up and label: photosphere, prominence, corona.
Answers to the book's problems
Glowing hydrogen gas. Only during a total eclipse of the Sun, when the Moon covers the bright face. (Photographs of eclipses are the easy way to enjoy it.) Because the Sun is so enormous; even though it is less dense than the Earth, its huge size gives it great weight and pull.
Worked out for this site from the scan. If a number in your copy differs, trust the book.