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The Moon And Earth

The Moon And Earth image
Parent Issue
Day
20
Month
February
Year
1880
Copyright
Public Domain
OCR Text

Tiikn if we pass back into tha preceding ages we must compute the time for the earth to cooi down from a molten state. Biaohoff, the. Germán determines by experimenta wiih moltei rock, and he is stipported by llehi! boltz, that tho period required for tht, earth to cool from 2,000 deg. Centrigrade to 200 deg. is 350,000,000 yews. BUchoff probably erred in ander estimating rat her' than iu overestimating tlic period; but if we take this period as probable and add to it the sueoeeding Unie. we have 460,000,000 y.uirs since the earth was a nebnlar niass, and in round numbers nmy declare 00,000,000 yeaw the age oí our planet. Mucn longer periods are required for the larger planeta, lii estiiuating time in planetary life we must upply Newton s principie tliat the larger the planel the longer the stages of its exlStenoe. We lind that if we heat two iron balls, one un inch in diameter and the other two iuehes in diameter, it will take twice as long for the lattcr to cool as the formcr, for although it has four times as imich mass it has eight times as much surfaee from wliich all heat must depart. The planet Júpiter in mass is nearly 34;S times as large as the earth; 348 is equal to the cube of seven; for Júpiter, theu, to reaeh the same density of the earth, it would take seven times as many years, or seven times 850,000,000, equal to 2.4.50,0007000, and ailowing the same proportion for subsequent changos, for Júpiter to reaeh the po'mt the earth has would require 3,000,000,000, or 3,000.000,000 more years than the earth. lint Júpiter is still far younger in development than is our planet. When we turn to the sun we reaeh far higher figure Following the same rul, as thentó,.of the sun is 340,000 times greater than that of the earth, its age will be seventy times as gréat, and we flnd that it would take 35,000,000,000 years ior the sun to reaeh the earth' s present state. Considering the smaller orbs, as the moon, we find that the past pe.riod is comparatively brief, but that the earth will reaeh the same condition fai in the remote ful ure. The moon in nass is 81 times less than the earth, nd its surface is as 1 to 13. By dividiug 81 by 13 we find how many times thj comparative age of the moon is less than the earth' s. This gives 83,000,000 years as the time it took for the moon to reaeh a condition similar to thé present stage of the earth's existence, The earth is behind the moon aboit 420,000,000 years, and, as the moon goes on six times as fast as the earth, 420,000,000 multiplied by 6 gives us 2,505,000,000 years before we sliall see th earth as the moon now is. From the present condition tf the moon we learn what to expect on our earth. Our planet, now in full life, will in 2,500,000,000 years bc .h cvtreme oíd age. These periods of normous duration of time sink into.nsi"-nilicance before the historj of the solar system as a whole. We find a wide relation between the parts of the solar system, iu that sll the planeta, from tho mightiest globe to the smallest satellite, except one of Uianus, move in their paths in the same lirection. Astronomers would be as much surrrised to see one of the asteroids - of which 200 have been discoveied - going in the opposite directionas to see the sun rise in the west. All the heavenly bodies are pans of some mighty whole. By the nebular hypothesis, the whole solar system was once an enoraious mass of gaseous matter, which began turning like a disc. Then the outer part became dissevered and formed one orb; the next and the next lol owed, until there was only a central sun left to rule the entire system. Eaeh planet went througï the same procesa, rings af ter rings and satcllites aftor salellites were formed. This nebular theory accounts fat the general features. It is not opposíR by facts. The meteoric system must also be considered. Professor Newtoi, of ï ale College, estimates that the rth is iucreased by 400,000,000 every ff&T. This may amount to thousands of tons of matter, but it is nothingasconipared with the mass of tho earth. Still we may say the earth is growtag; but her growth is only like that of one who has already attained full stature. These meteors are only the residue of a residue, the few left out of the raillions of the past. In the remote ages the earth must have met far more. From a rough calculation I made, I find that my assumption must have been wrong, or the earth would have increased ten-fold more than she did. But we may rightly contend that no small part of the mass of the earth is formed from meteoric aggregations. If we take La Place' s theory with the meteoric, we may account for the present condition of our planet. And as the earth, and indeed all matter we know - our bodies and brains - have come down from the heavens, is it any wonder that ai] our higher thoughts and aspirations are heavenward 't -Report in N. Y. Tribune af a Recent Lecture by Prof. Proctor.

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Subjects
Old News
Ann Arbor Argus