TO KXOW THE STARRY HEAVEXS 



357 



The star at K, for example, is made up 

 of two beautiful suns, three seconds 

 apart, of which the larger is greenish- 

 white and the fainter one blue. A some- 

 what similar beautiful double pair is 

 in Leo at L, while the brilliant Regu- 

 lus has a deep blue companion, one 

 minute away, which is itself a double 



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The April Stars. 



To the east of Leo, there is the very 

 large summer group \^irgo, which for 

 the first time this year is seen to have 

 completely entered the evening sky. 

 The beautiful Spica is the most strik- 

 ing object of this constellation. This 

 remarkable star is now known to be 

 revolving about a dark and unseen 

 companion with a speed of fifty-six 

 miles a second. It thus passes com- 

 pletely around its orbit, which is six 

 millions of miles in diameter, in the 

 course of only four days. The system 

 is very like that of the well-known 

 Algol, at M, Figure i, but the path of 

 Spica lies in such a position that we 

 never see the dark companion pass 

 between the bright star and us, and so 

 cut ofif its light, as so frequently hap- 

 pens with Algol. It is in the region, 

 N, of this constellation that there are 

 found more of these wonderful shin- 

 ing clouds called Nebulas than in any 

 other equal area of the sky. 



North of Virgo the observer will at 

 once notice the great golden star, 

 Arcturus. This is at the foot of 

 Bootes, the Driver, who with up- 

 stretched arms is forever driving the 

 Bear before him in its ceaseless jour- 

 ney around the Pole. And below 

 Bootes is the beautiful Northern 

 Crown, while still nearer the ground 

 there has now fully appeared the 

 group Hercules, with its wonderful 

 cluster of sixty thousand stars, at R. 

 In short, the whole southern and east- 

 ern heavens are so crowded with ob- 

 jects of interest, that we need not regret 

 the withdrawal of the brighter winter 

 stars, which is now proceeding so rap- 

 idly in the west. 



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A New Periodic Comet. 



There are two new comets in our 

 northern heavens, both of which are 

 extremely faint objects and only visi- 

 ble in larger telescopes. Nevertheless 

 the first of these is of great interest be- 

 cause it has been found to be following 



so very small an orbit around the sun 

 that it is destined to continually re- 

 appear in our heavens in the years to 

 come. Many most interesting specu- 

 lations arise from a study of these 

 periodic comets, especially when they 

 move in paths so small that they may 



Figure 



The path of the new comet about the sun. 



be observed from the earth during a 

 great part of their motion. 



The path of the new periodic comet 

 is shown in Figure i. It was discov- 

 ered at the Cape of Good Hope on last 

 December 2, at which time it was very 

 near the western end of the Belt of 

 Orion. Its apparent motion carried it, 

 first through Taurus, and then into 

 Gemini ; during the present month it 

 will move from the latter constellation 

 into the faint group of stars known as 

 the Lynx. 



When a new comet is thus found 

 moving among the stars, it is only 

 necessary to determine accurately its 

 position on three dififerent nights ; know- 

 ing these three positions the mathe- 

 matician can compute its exact path 

 in space and tell where it Avas to be 

 found in the heavens at any desired 

 date, either in the past or in the 

 future. Nearly all comets fall toward 

 our sun from an immense distance 

 away, swing around that body, and 

 recede into space never to be seen by 

 us again. The paths of such comets is 

 a curve called a parabola, which close- 

 ly resembles the curve MPN, Figure 2. 



The long computation necessary to 

 find how a comet is moving is much 

 shortened if we assume in the begin- 



