TO KNOW THE STARRY HEAVENS 



189 



heavens from the east to the west. 



It is the conspicuoiisness of the Pleia- 

 des al this tiiiK' which has given to No- 

 veniher the name of the Pleiad month. 

 It was with this monlli that many of the 

 primitive people began their year; on the 

 "Pleiad Night" which was the night on 

 which the Pleiades were found due south 

 at midnight, no petition was presented in 

 vain to the ancient kings of Persia. The 

 Pleiad Night of the present year will oc- 

 cur on November 20. A memory of the 

 midnig"ht rites of the Druids on the first 

 of November still survives in our Hallow- 

 eve. 



Probably nearly every reader of these 

 monthly articles is familiar with the three 

 brilliant winter constellations now shining 

 just above the ground in the east. They 

 have examined the wonderful golden star, 

 Capella, and perhaps traced out all of its 

 constellation, Auriga, and also the inter- 

 esting Perseus now just above it. They 

 have perhaps many times examined the 

 wonderful double cluster of stars at C. 

 figure I, and watched one or more of the 

 eclipses of the remarkable variable star, 

 Algol, at K — the star which loses no less 

 than five-sixths of its light at the constant 

 interval of a little less than sixty-nine 

 hours. 



But many observers are not aware of 

 the wealth of interesting objects to be 

 found within the borders of au)^ one of 

 the fainter, little known, constellations. 

 This month, for example, the widespread 

 group of Cetus, or the Sea Monster, is in 

 excellent position for observation, and 

 will well repay a careful exploration with 

 a small telescope. 



Its brightest star, at D, has a bluish, 

 fifth magnitude companion west of it 

 which is easily visible in a small glass, 

 Mhile the stars at E, B and P are also all 

 beautiful doubles. The first of these 

 is the most beautiful double star in this 

 part of the sky, its principal sun being 

 golden and its companion blue ; around 

 the last there are many distant compan- 

 ions, one of which, lying due north of it. 

 is an interesting double star. 



The most interesting feature of Cetus, 

 however, is the remarkable group of vari- 

 able stars which are found within its 

 borders. One of these at the point F, a 

 little to the left of the line joining H and 

 L, varies from the seventh to the tenth 



magnitude in a period of eleven months, 

 while the star at N changes from the 

 seventh to the thirteenth magnitude in 

 one-half of this lime. 



* :!: * :;: * 



The Variable Star, Mira. 



But the most remarkable of all the 

 variables is the bright star at M, Figure i, 

 which is known as the Mira, or the 

 "Wonderful Star." This great sun in- 

 creases in brightness sometimes fifteen 

 hundred- fold at a quite regular interval 

 of about eleven months. xAnd its wonder- 

 ful increase of briglitness will take place 

 during the present month when the con- 

 stellation is favorably situated in our 

 evening heavens ; the observer will there- 

 fore have a very unusually favorable op- 

 portunity of witnessing it. 



On November i the star may be seen 

 with some difficulty with the naked eye, 

 though with a pair of opera glasses it 

 may readily be found, almost on a straight 

 line between the brighter stars, A and B. 

 As the weeks go by, it will at once be 

 noticed that its brightness is increasing 

 very rapidly indeed, until by the end of 

 the month it may become a conspicuous 

 naked eye star. The date of its greatest 

 brightness will be about December 5 ; it 

 will remain thus bright for a week or ten 

 days and then rapidly fade away. 



Sometimes when at its brightest this 

 star has been known to almost equal 

 Aldebaran ; at others it has been but lit- 

 tle brighter than the Pole star, while a 

 very few of its outbursts have been so 

 feeble that it has even been scarcely visi- 

 ble to the naked eye at all. We cannot 

 therefore predict to exactly what bright- 

 ness the star will rise during the present 

 month, but it is quite certain that it will 

 furnish a most interesting object for 

 study. As to the causes which lead to 

 such enormous increases in its light and 

 heat, we are, as yet, wholly ignorant. 

 Eclipses of Jupiter's Satellites. 



Several letters have been received from 

 those who have been observing Jupiter's 

 satellites, asking for a more complete ex- 

 planation of the, at first sight, peculiar 

 behavior of these little bodies. One ob- 

 server has noticed that while the first and 

 second moons are never seen to go into 

 eclipse, yet they are seen to emerge from 

 it, and that the third, moon, after it has 

 passed behind the planet and again re- 



