Other Stars and Constellations 



205 



FIG. 131. Canis Major, or the Big Dog. 

 Sirius, the brightest star in the heavens, 

 is in this constellation. 



at the middle of the 

 sword, is hazy. A tele- 

 scope shows that it 

 consists of six stars and 

 a great quantity of star 

 mist, forming a nebula. 

 With a telescope many 

 nebulae can be seen in 

 the heavens, but with 

 the naked eye very few. 

 The sun, with the earth 

 and other bodies that 

 revolve around it, is 

 believed to have been a 

 nebula hundreds of mil- 

 lions of years ago. 



Sirius, the Dog Star. Orion, the Hunter, is followed 

 by the Big Dog, Canis Major, whose brightest star is 

 Sirius. Canis Major is south of the ecliptic and rises 

 a little later than Orion. Sirius is farther south than 

 any other first-magnitude star visible in this latitude 

 throughout the winter evenings. It is the brightest in 

 the heavens, giving us n times as much light as an 

 average first-magnitude star. If it were no farther away 

 than the sun, it would give us more than 40 times as 

 much light as the sun ; but it is about 550,000 times as 

 far away. Consequently the light we receive from it is 

 i i 



7 \- or > 



(5 50,OOO) 2 302,500,000,000 



of the amount we should receive if it were at the sun's 

 distance. 



