ii82 Home Nature-Study Course. 



(8). How far apart from each other are the nearest neighbors of the 

 Pleiades ? 



(9). What do the astronomers think about the Pleiades and why 

 do they think this? 



Facts for teachers. — Almost in line with the belt of Orion and northwest from 

 it may be seen in winter evenings a rosy star not so red as Betelgeuse. This is 

 Aldebaran which lies about half way between the belt and Pleiades. Aldebaran 

 is a comparatively near neighbor, as it takes only thirty-two years for its light 

 to pass from it to us. This ruddy star marks the end of the lower ann of a V- 

 shaped constellation composed of this and four other stars, which is called the 

 Hyades. Aldebaran is a part of the constellation called Taurus, the bull, and 

 is the eye of the infuriated beast. 



Although the eye is attracted by many bright stars in the winter sky, yet there 

 is a little misty group of stars which has ever held the human attention and of 

 whom the poets of all ages have sung. These stars are called the Pleiades, and 

 some eyes can count six stars in the group while others can see seven or eight. 

 There are nine larger ones, seen through the telescope, which bear names; but 

 sky photography has revealed that there are more than three thousand stars in 

 this little group. Perhaps no stars in the heavens give us such a feeling of the 

 infinity of the universe as do the Pleiades; for astronoraers believe that they form 

 a great star system which is now evolving from a nebula. The reason for this 

 belief is that these stars are surrounded by the brilliant mist which sometimes 

 seems to be looped from one to another, and they are all of the same stage of 

 development and chemical composition, and are all moving together in the same 

 direction. These stars which look so close together to us are so far apart that our 

 own solar system could roll in between them and never be noticed. It would 

 require several years for light to travel from one of these stars to another and 

 the group is so far from us that we cannot estimate its distance, but know that 

 it takes light several hundred years to reach us from it. There is a mythical 

 story found in literature that once the unaided eye could see seven instead of six 

 stars in the Pleiades. 



Lesson XXXI. 



THE DOG STARS SIRIUS (So're-US) AND PROCYON (Pro'se-Ofl). 



Purpose. — To learn to know and to find the Dog Stars. 



(i). After Orion is well up in the sky a straight line drawn through 

 and dropping down to the eastern horizon and about as far southeast 

 from the belt as Aldebaran is northwest, is the most beautiful star in 

 our skies, called Sirius, the Great Dog Star. 



(2). What color is Sirius and from its colors what stage of develop- 

 ment do you think it is in ? 



(3). How large is Sirius compared with our sun? 



(4). How near is it to us and why is it called the Dog Star? 



(5). Imagine a line drawn from Betelgeuse to Rigel crossing Orion's 

 t>elt, then from Rigel to Sirius, and then try to complete this square 



