238 ASTRONOMY. 



V E N U S 

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Is distant from the sun nearly sixty nine millions of miles, she revolves 

 round him in two hundred and twenty-four days and seventeen hours; 

 and on her own axis in twenty-three hours and twenty-three minuses. 

 She is seven thousand seven hundred and forty-three miles in diameter, 

 moves in her orbit at the rate of eight thousand two hundred and ninety- 

 five miles per hour, and her diurnal rotation is one thousand nine 

 hundred and forty-three miles in the same space of time. Her greatest 

 distance from the sun is never more than forty-eight degrees, so that she 

 never appears in the east when the sun is in the west, nor in the west 

 when the sun is in the east. When Venus is observable in the morning 

 before the rising of the sun, she is called by astronomers Phosphorus, 

 or the morning star, and sometimes, after the sun's setting, when she 

 is termed Hesperus, or the evening star. Venus is, of all planets, the 

 most beautiful, and emits the brightest rays ; she is the second planet 

 from the sun. 



THE EARTH, 



Like other planets, is not a perfect sphere, its equatorial diameter being 

 seven thousand nine hundred and sixty- four miles, while its axis is seven 

 thousand nine hundred and thirty miles; showing a difference of rather 

 more than thirty miles. Her distance from the sun is ninety-five millions 

 one hundred and seventy- three thousand miles, and she makes her revolu- 

 tion round him in three hundred and sixty-five days six hours nine minutes 

 and a quarter, which is her year. The axis of the earth is not perpen- 

 dicular to the plane of her ecliptic, but inclined to it at an angle of twenty- 

 three degrees twenty-eight minutes; round this axis she revolves in 

 twenty-three hours fifty-six minutes and four seconds, which is the 

 length of the astronomical day. 



The inclination of the earth's axis (says Mr. Pinnock), is the principal 

 cause of the variety or change of seasons ; for as the axis of the earth 

 always preserves its parallelism in her revolution round the sun, at one 

 part of her orbit she receives most of the light and heat on her northern 

 hemisphere, and at another part on her southern, according as her north 

 or south pole is turned towards the sun ; while in two points of her 

 orbit both hemispheres are equally enlightened. That the earth is a 



