The Heavens 157 



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pole. The relative temperatures in the northern and southern 

 hemispheres are now about the same, while it is hottest at the 

 equator because the sun's rays strike it vertically. When the 

 earth is at the point represented by B, it is autumn in the north- 

 ern hemisphere and spring in the southern. 



Move the globe to point C, and then to D, and account for the 

 variations in the intensity of heat and light on the different parts 

 of the earth's surface. 



Make a labeled drawing showing the path of the earth around 

 the sun. Draw globes representing the earth at points C and D. 

 Draw lines which show how the rays of the sun strike the earth 

 on December 22 and March 21. 



Solar Eclipse. Whenever the moon comes between the 

 earth and the sun a solar eclipse occurs; that is, the direct rays 

 of the sun are prevented from reaching certain portions of the 

 earth. The eclipse may be partial or total. It is partial when 

 only a portion of the sun's disk is hidden, and total when the entire 

 disk is obscured. Total eclipses are not common. One occurred 

 on the 26th of January, 1925, that was visible in parts of this 

 country. 



Latitude and Longitude. Latitude is distance in degrees 

 north or south of the equator. Longitude is distance east or west 

 of a certain pole-to-pole line, or meridian, known as the prime 

 meridian. The prime meridian passes through Greenwich, near 

 London, in England. Knowledge of the latitude and longitude 

 of places is important in travel and in reckoning time. 



A circle contains 360 parts, or degrees. The distance between 

 the earth's equator and each pole, a quarter of a circle, is divided 

 into 90 parts, each about 69 miles long, or 1/360 of 25,000 miles, 

 the earth's circumference. Each part is called a degree and its 

 sign is (). The first east-west line, or parallel of latitude, 

 north of the equator is 1, or about 69 miles, from the equator. 

 The parallel 2 north is twice that distance, and so on. All points 

 on any one of these parallels are the same distance from the 

 equator and from each of the other parallels. So if you know 

 that a place you wish to locate is on the 9th, or the 43rd, or any 

 other parallel of north latitude, you can easily estimate how many 



