Handbook of Nature-Study · Lesson CCXXX · Topic 37: The stars
230. Capella and the Heavenly Twins
Goal: Your child can find Capella and the Twins, Castor and Pollux, high overhead on winter evenings.
You'll need
- A clear winter evening
- A red-covered flashlight
- A nature notebook and a pencil (colored pencils if you have them)
What's in the book
The lesson has a leading thought, a method for finding Capella with lines drawn from the Big Dipper and the Pole-star, and seven observations on Capella, its constellation and the Heavenly Twins. A short introduction to the stars of summer follows.
The lesson, step by step
When and where
Evenings in January and February, about 8 or 9 p.m. Look almost straight up; lying on a blanket helps. Stargaze with an adult, in a dark spot away from roads, such as a back yard or a field you have permission to use. Dress warmly, bring a blanket, and cover a flashlight with red cellophane or a red balloon so your eyes stay used to the dark.
The leading thought
There are, during the evenings of January and February, three brilliant stars almost directly overhead. One of these is Capella, the other two are the Heavenly Twins.
Find Capella
Draw a line from the Dipper's pointers to the Pole-star. From the Pole-star, turn a right angle away from the Dipper's handle. That line passes through a big, bright yellow star: Capella.
What color is Capella, and how does its color compare with that of our sun?
Can you see the shield-like constellation of which Capella is a part? Do you know the name of this constellation?
The Twins
Why are these stars called the Heavenly Twins? What is their Latin name? What are the names of the two stars? Are these twins set nearer together than the pointers of the Big Dipper?
How can you tell the Heavenly Twins from the Little Dog Star and its companion?
What we know now
The book invites you to find out whether the Twins are really as near together as they seem. They are not: Pollux is about 34 light-years from us and Castor about 51, so they only look side by side. Castor is itself a family of six stars, and Capella is a pair of big yellow giant stars circling each other, too close together to see apart even with a telescope.
Nature notebook
Draw the Big Dipper, the Pole-star, Capella and the Twins with the lines you used to find them.
Answers to the book's problems
Capella is yellow, like our Sun. Its constellation is Auriga, the Charioteer. North of about 44 degrees latitude Capella never sets. The Twins are Gemini; the two bright stars are Castor and Pollux. They are farther apart than the Dipper's pointers. Ancient sailors thought of the Twins as protectors of ships.
Worked out for this site from the scan. If a number in your copy differs, trust the book.