|
|
The natural time for beginning star study is in the autumn when the days are shortening and the early evenings give us opportunity for observation. After the polar constellations are learned, we are then ready for further study in the still earlier evenings of winter, when the clear atmosphere and beautiful blue of the heavens make the stars seem more alive, more sparkling, and more beautiful than at any other period of the year. One of the first lessons should be to instruct the pupils how to draw an imaginary straight line from one star to another, and to perceive the angles which such lines make when they meet at a given star. A rule, or what is just as effective, a postal card or some other piece of stiff paper which shows right-angled corners, is very useful in this work. It should be held between the eyes and the stars which we wish to connect, and thus make us certain of a straight line and a right angle.
To use the chart take it in the hands, face the Pole-star and hold the chart above the head so that the side marked east will extend eastward.
During the evenings of January, February and March the splendid constellation of Orion (o-ri'on) takes possession of the southern half of the heavens; and so striking is it that we find other stars by referring to it instead of to the Pole-star. Orion is a constellation which almost everyone knows; three stars in a row outline his belt, and a curving line of stars, set obliquely below the belt, outline the sword. Above the belt in the evening sky we can see the splendid red star Betelgeuse (bet-el-gerz), and below the belt, at about an equal distance, is the white star Rigel (re-jel). West of the red star above, and east of the white star below, are two fainter stars, and if these four stars are connected by lines, an irregular four-sided figure results, which includes the belt and the sword. In this constellation the ancients saw Orion, the great hunter, with his belt and his sword; Betelgeuse was set like a glowing ruby on his shoulder, and the white star Rigel was set like a spur on his heel. Thus, stood the great hunter in the sky, with his club raised to keep off the plunging bull whose eye is the red Aldebaran (al-deb'a-ran). And beyond him follows the Great Dog with the bright blue star Sirius (sir'i-us) in his mouth, and the Little Dog branded by the white star Procyon (pro'si-on). However, our New England ancestors did not see this grand figure in the sky; they called the constellation the Yard-ell or the Ell-yard.
The three beautiful stars which make Orion's belt are all double stars; the belt is just three degrees long and is a good unit for sky measurement. The sword is not merely the three stars which we ordinarily see, but is really a curved line of five stars; and what seems to be the third star from the tip of the sword and which looks hazy, is in fact a great nebula. Through the telescope this nebula seems a splash of light with six beautiful stars within it. Betelgeuse is a brilliant red star, and is the first star in the constellation to appear above the horizon. It is an old, old star and is growing cold, as is shown by its red glow. It glows redder sometimes than at others; it is so far away that we have not been able to measure its distance from us surely, and it is receding from us all the time. About fifteen minutes after Betelgeuse rises, and after the belt and sword are in sight, a white sparkling star appears at the southwest of the belt. This is Rigel, and this star, too, is so far from us that we do not know the distance, and it is also receding.
Leading thought—Orion is one of the most beautiful constellations in the heavens. It is especially marked by the three stars which form Orion's belt, and the line of stars below the belt which form the sword.
Method—Place on the blackboard the outline of Orion as given in the diagram. Ask the pupils to make the following observations in the evening and give their report the next day.
Observations—
1. Where is Orion in relation to the Pole-star?
2. How many stars in the belt of Orion? How many stars in the sword? Can you see plainly the third star from the bottom of the sword?
3. Notice above the belt, about three times its length, a bright star; this is Betelgeuse. What is the color of this star? What do we know about the age of a star if it is red?
4. Look below the belt and observe another bright star at about the same distance below that Betelgeuse is above. What is the color of this star? What does its color signify? The name of this star is Rigel.
5. Note that west of the red star above and east of the white star below are two fainter stars. If we connect these four stars by lines we shall make an irregular four-sided figure, fencing in the belt and sword. Sketch this figure with the belt and sword, and write on your diagram the name of the red star above and the white star below and also the name of the constellation.
6. Which star of the constellation rises first in the evening? Which last?
7. Write an English theme on the story of Orion, the great hunter.
Supplementary reading—Stories of Starland, Proctor; The Stars in Song and Legend, Porter; Storyland of the Stars, Pratt.