The Planets 235 





lower row the comparative sizes of the sun as viewed from each of the planets. 



causes, but mainly to the varying distance from the 

 earth. 



From Figure 143 it is evident that the distance be- 

 tween Earth and Mars is much less when both planets 

 are in the same direction from the sun than when one is 

 on one side of the sun and the other on the other side. 



How to distinguish one planet from another. The 

 three brightest planets, if no others, should become 

 familiar to you so that you can recognize them as you 

 do the moon and the sun. Venus, when brightest, 

 gives us more light than any other heavenly body except 

 the sun and the moon. Look for it in the west after 

 sunset, or in the east before sunrise. When Jupiter is 

 in the eastern sky in the evening, it is unsurpassed in 

 brightness by any other heavenly body in that part of 

 the heavens, unless the moon happens to be there, too. 

 Mars, when in the east in the evening, is brighter than 

 any fixed star. It may be known from Jupiter by its 

 red color. 



