TO KNOW THE STARRY HEAVENS 



259 



While so much occurs of special in- 

 terest we will have but little space to write 

 of those heavenly objects that are with us 

 for a longfer time. The possessor of a 

 small telescope will not fail to remember, 

 however, that the great nebulas of Orion 

 and Andromeda, the Praesepe. the Plei- 

 ades, the Double Cluster in Perseus, and 

 the stars. Sirius, Regulus. Capella and the 

 blood-red star in Lepus. are now all in 

 excellent position for observation. 



after attaining its greatest brilliance it 

 will rapidly fade away, and soon there 

 will be no trace of any object in this part 

 of the heavens, unless a telescope is em- 

 ployed. As with many variable stars of 

 this kind, it may be continuously followed 

 with telescopic aid. and as it grows fainter 

 will be seen to become a deep red color. 



Mira is a great sun which is usually 

 fainter than the ninth magnitude. At an 

 interval of about every eleven months. 



Figure 2. Curve showing the variation in the observed magnitude of Mira through 

 tvjro periods, or during an interval of about twenty-two months. During recent years the 

 maximum brightness has been slightly greater than even the first (Ligh) maximum here 



The Variable Star, Mira. 



This wonderful and interesting object 

 will be found in the position indicated in 

 Figure i. If the observer will face to- 

 ward the southwest in the early evening 

 he will probably have but little difficulty 

 in finding the quadrilateral formed by the 

 four stars, B, C, D and E, which at this 

 time are past the meridian but are still 

 well up from the horizon. These four 

 stars, together with either the star at A 

 or the two stars. A and H. form the figure 

 of a small inverted dipper. 



If now a straight line be imagined 

 drawn from E to D. and extended up- 

 ward, it will almost meet the star at F. 

 which star is Nodus, the knot in the cord 

 which binds the two Fishes together. It is 

 just below this star that there now shines 

 out the wonderful Mira. A few weeks 

 ago. had the observer looked at this part 

 of the heavens, he would have seen no 

 trace of this star with the naked eye. 



All of the stars in this region of the 

 sky are unfortunately rather faint ones — 

 it is the extreme eastern border of the 

 faint, summer heavens, but it is hoped 

 that from the above directions the reader 

 will be easily able to locate this variable 

 star. If he will look at it from time to 

 time as the weeks go by. he will see that 



however- some stupendous disturbance 

 begins within it and the amount of light 

 and heat which it pours out begins rapidly 

 to increase, until within a few weeks it 

 becomes thousands of times as great as 

 when the sun was quiescent. Sometimes, 

 for many years, Mira has only brightened 

 to a faint star of less than the fourth 

 magnitude ; in other years it has risen to 

 nearly the first magnitude, and it is re- 

 ported that sometimes for many vears 

 consecutively it has not grown bright 

 enough to be seen with the naked eye. 



The present maxinunn is due to occur 

 on January 8, but as the interval between 

 brightenings is for some reason quite 

 irregular, the date ma\- var\- even so much 

 as a week or two from this. Nor can we 

 predict exactly how bright Mira will 

 grow ; but since, during the past few- 

 weeks, its brightness has increased an 

 hundredfold it is probable that the pre- 

 sent brightening will be a notable one. 

 The magnitude of the star at B, Figure i, 

 is ^.6; that of the star at C is 3.8; of D 

 is 3.9; of E is the 3.6, and of F is 4.0. 

 Mira will certainly become conspicuously 

 brighter than any of these stars and it 

 will probably exceed even the star at H, 

 whose magnitude is 2.2. It will probably 

 become when brightest from three to six 



