9o6 Handbook of Nature-Study 



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is here. A letter which weighs an ounce here would weigh almost a pound 

 and three quarters on the sun; and a man of ordinary size in this world 

 would weigh more than two tons there, and would be crushed to death by 

 his own weight. Find how much your watch, your book, your pencil, your 

 baseball, your football would weigh on the sun. 



Our Sun and its Family 



First of all we shall have to acknowledge that our great, blazing sun is 

 simply a medium-sized star, not nearly so large as Vega, nor even as large 

 as the Pole-star ; but it happens to be our own particular star and so is of 

 the greatest importance to us. The sun has several other worlds, more or 

 less like our own, revolving around it on almost the same level or plane in 

 which our world revolves, but some of these worlds are much nearer the sun 

 and others much farther away than ours. Nearest of all is Mercury, but it 

 is not half so thick through as our earth, and it is so close to the sun that it 

 circles around in 88 days ; that is, its year is only 88 days long. Next comes 

 Venus, almost as large as the earth, with a year 225 days long; next comes 

 our earth, which completes its year in 3 6 5 days ; next beyond us is Mars, a 

 little more than half as thick as the earth and with a year 687 days long; 

 beyond Mars is a group of small planets which are not large enough to be 

 seen with the telescope, but we know that one of the largest of the group is 

 only 490 miles through; beyond this mysterious swarm of little worlds is 

 great Jupiter almost ten times as thick through as the earth, and it is so far 

 away that it does not circle about the sun but once in 1 1 years ; beyond 

 great Jupiter comes Saturn, not quite ten times the diameter of the earth 

 and so far from the sun that it takes 293^ years for it to move around its 

 orbit; beyond Saturn is Uranus, only about four times as thick through as 

 our world, and it has a year 84 years long; but the outermost of aU our 

 sun's planets is Neptune, little larger than Uranus, but so far from the 

 sun that 165 years are required for it to complete its circle. Just think 

 of a spring or a winter 41 years long! If Methuselah had lived on Nep- 

 tune, he would have died before he was five and one-half years old. 



Almost all of the Earth's sister planets are better o£E for moons than she ; 

 neither Venus nor Mercury has any moons. Mars has two moons, Jupiter 

 five and Saturn has nine besides some splendid rings ; and a queer thing 

 about one of Saturn's moons is that it revolves in an opposite direction from 

 the others. Uranus has four moons, while Neptune is not any better ofl 

 than we are, unless, there are some we have not been able to discover 

 because they are so far away. 



One peculiar thing about all of the planets of the sun's family and all of 

 their moons is that they all shine by reflecting the light of the sun, and none 

 of them are hot enough to give off light independently; but these sister 

 worlds of ours are so near us that they often seem larger and brighter than 

 the stars, which are true suns and give off much more light than our own 

 sun. After a little experience the young astronomer learns to distinguish 

 the planets from the true stars ; the planets alwaj^s follow closely the path 

 of the sun and moon through the sky ; they often seem larger and brighter 

 than the true stars and do not twinkle so much. The so-called morning 

 and evening stars are other planets of our sun's family and are not stars at 

 all. 



Dr. Simon Newcomb in his delightful book, "Astronomy for Every- 

 body," gives the best illustration to make us understand the place of our 



