Handbook of Nature-Study · Lesson CCXXV · Topic 37: The stars
225. The two Dippers and the Pole-star
Goal: Your child can find the Big Dipper, use the pointers to find the Pole-star, find the Little Dipper, and see that the Dipper circles the Pole-star.
You'll need
- A clear, moonless evening
- A red-covered flashlight
- A blanket and warm clothes
- 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 (begin when the Moon is in its last quarter, and draw the Dipper on the blackboard first), twenty-four observations and thinking questions about the Big Dipper, the Little Dipper and Polaris, and topics for writing.
The lesson, step by step
When and where
Any clear evening of the year, when the Moon is not up in the early evening (the book says start when it is in its last quarter). Go out about an hour after sunset. Face north. 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.
Before going out, draw the Big Dipper on paper with a line through its two end stars, the "pointers," to the Pole-star, as the book shows on its chart.
The leading thought
The North Star or Pole-star may always be found by the stars known as the pointers in the Big Dipper; the stars of the Big Dipper seem to revolve around the Pole-star once in twenty-four hours.
Find the Big Dipper
Can you find the Big Dipper among the stars
Which stars are the "pointers" in the dipper, and why are they called so?
How many stars make the bowl of the Dipper?
How many stars in the handle?
Does it move?
Does the Big Dipper remain in the same direction from the Pole-star all night? Look at it at seven o'clock and again at nine o'clock and see if it has changed position?
How could you tell the time of night by the Big Dipper and the Pole-star?
The Little Dipper
The end of the Little Dipper's handle is the Pole-star itself. Its stars are faint, so you need a dark sky.
Is the Little Dipper nearer or farther from the Pole-star than the Big Dipper?
How many stars make the bowl of the Little Dipper? Which of these stars are the brightest?
Thinking questions
Ask indoors, afterward:
If you could stand at the North Pole, where would the Pole-star seem to be?
How does the North Star help the sailors to navigate the seas and why?
What we know now
The Dipper turns once in a little less than 24 hours (23 hours 56 minutes), because the Earth turns. Polaris is not exactly at the pole, but within about one degree of it. The Earth's axis wobbles very slowly, so thousands of years from now another star, such as Vega, will be the pole star.
Nature notebook
Draw the Big Dipper, the pointers and the Pole-star as you saw them at a set hour. Go out again two hours later and draw them again on the same page.
Afterwards
Check the Dipper at the same hour once a month. Its position at 8 p.m. changes with the seasons, which the book asks you to record from January to April.
Answers to the book's problems
Four stars in the bowl and three in the handle; the handle is curved. The pointers point to the Pole-star. The Dipper circles the Pole-star counterclockwise (when you face north) about once a day, so it can be read like the hand of a clock. In the northern United States and Canada it never sets. At the North Pole, the Pole-star would be straight overhead, and the stars would circle around without rising or setting. The Pole-star cannot be seen from far south of the equator. A light-year is the distance light travels in a year, about six trillion miles.
Worked out for this site from the scan. If a number in your copy differs, trust the book.