520 SCIENCE OF HOME AND COMMUNITY 



the summer than winter. This inclination of the sun's 

 rays has more effect in producing the change of seasons 

 than our distance from the sun. This explains the fact that 

 we have our winter when we do, in spite of the fact that we 

 are nearer the sun at that time. The fact that the sun 

 shines for a longer part of the day in summer than in winter 

 is another reason why our summers are hotter. In the 

 southern hemisphere the conditions and the seasons are 

 the reverse of those in the northern hemisphere. 



Moon. As the earth revolves around the sun, so the moon 

 revolves around the earth. While the earth's motion around 

 the sun takes a year, the moon's motion around the earth 

 takes a month (29^ days). It is the nearest of the heavenly 

 bodies, being situated about a quarter of a million miles 

 distant. Its diameter is about two thousand miles, or 

 one quarter that of the earth. 



Light of moon. The moon affects man in two ways, by 

 giving light and by causing the tides. The moon gives 

 enough light so that in some towns and cities the electric 

 street lamps are not lighted on clear moonlight nights, thus 

 effecting a saving in expense. The light that we get from the 

 moon is reflected sunlight, as the moon has no light-giving 

 power in itself. 



Tides. Another way in which the moon affects life on 

 the earth is by causing the tides. The tides have a beneficial 

 effect as they help to clear away decaying matter around 

 the shores, which might otherwise collect and become 

 offensive. The tides are caused by the attraction that the 

 moon has on the oceans, by which the water is lifted a few 

 feet toward the moon. As the earth rotates, these high tides 

 follow the moon, though lagging behind it. As the moon 

 rises later each day, so the high and low tides occur that 

 much later each day. The sun also has some influence in 

 forming the tides, but it is so far away that, in spite of its 

 great size, it hasn't as much influence as the moon. 



