Heavenly Bodies Epub
Yvone Samiento
A treatise on celestial mechanics in the tradition of Newton's Principia. Here Laplace applied his analytical mathmatical theories to celestial bodies and concluded that the apparent changes in the motion of planets and their satelites are changes of long periods, and that the solar system is in all probability very stable. He gave methods for calculating the movements of translation and rotation of heavenly bodies and for resolving problemsof tides, from which he deduced the mass of the moon.
Sir William Rowan Hamilton, the eminentmathematician of Dublin, has, of all writersancient and modern, most fittingly characterizedthe ideal science of astronomy as man's golden chainconnecting the heavens to the earth, by which we"learn the language and interpret the oracles of theuniverse."
The oldest of the sciences, astronomy is also thebroadest in its relations to human knowledge andthe interests of mankind. Many are the cognatesciences upon which the noble structure of astronomyhas been erected: foremost of all, geometry and thehigher mathematics, which tell us of motions, magnitudesand distances; physics and chemistry, ofthe origin, nature, and destinies of planets, sun, andstar; meteorology, of the circulation of their atmospheres;geology, of the structure of the moon'ssurface; mineralogy, of the constitution of meteorites;while, if we attack, even elementally, thefascinating, though perhaps forever unsolvable,problem of life in other worlds, the astronomer mustinvoke all the resources that his fellow biologistsand their many-sided science can afford him.
Such results have been attainable only throughthe successful construction and operation of monstertelescopes that bring to the eye and visualize onphotographic plates the faintest of celestial objectswhich were the despair of astronomers only a fewyears ago.
So rapid, indeed, has been the progress of astronomyin very recent years that the present isespecially favorable for setting forth its salientfeatures; and this book is an attempt to presentthe wide range of astronomy in readable fashion,as if a story with a definite plot, from its originwith the shepherds of ancient Chaldea down topresent-day ascertainment of the actual scale of theuniverse, and definite measures of the huge volumeof supersolar giants among the stars.
Like life itself we do not know when astronomybegan; we cannot conceive a time when it wasnot. Man of the early stone age must have begunto observe sun, moon, and stars, because all thebodies of the cosmos were there, then as now. Withhis intellectual birth astronomy was born.
Onward through the childhood of the race hebegan to think on the things he observed, to makecrude records of times and seasons; the Chaldeansand Chinese began each their own system ofastronomy, the causes of things and the reasonsunderlying phenomena began to attract attention,and astronomy was cultivated not for its own sake,but because of its practical utility in supplying thedata necessary to accurate astrological prediction.Belief in astrology was universal.
The earth set in the midst of the wonders of thesky was the reason for it all. Clearly the earthwas created for humanity; so, too, the heavens werecreated for the edification of the race. All was subservientto man; naturally all was geocentric, orearth-centered. From the savage who could countonly to five, the digits of one hand, civilized manvery slowly began to evolve; he noted the progressof the seasons; the old records of eclipses showedThales, an early Greek, how to predict theirhappenings, and true science had its birth when[10]man acquired the power to make forecasts thatalways came true.
The earliest really sturdy manifestation ofastronomical life came with the birth of Greekscience, culminating with Aristarchus, Hipparchusand Ptolemy. The last of these great philosophers,realizing that only the art of writing prevents man'sknowledge from perishing with him, set down allthe astronomical knowledge of that day in one ofthe three greatest books on astronomy ever written,the Almagest, a name for it derived through theArabic, and really meaning "the greatest."
The system of earth and heaven seemed as iffinished, and the authority of Ptolemy and his Almagestwere as Holy Writ for the unfortunate centuriesthat followed him. With fatal persistencethe fundamental error of his system delayed theevolutionary life of the science through all thatperiod.
But man had begun to measure. Geometry hadbeen born and Eratosthenes had indeed measuredthe size of the earth. Tools in bronze and iron were[11]fashioned closely after the models of tools of stone;astrolabes and armillary spheres were first builton geometric spheres and circles; and science wasthen laid away for the slumber of the DarkAges.
Nevertheless, through all this dreary period thelife of the youthful astronomical giant was maintained.Time went on, the heavens revolved; sun,moon, and stars kept their appointed places, andArab and Moor and the savage monarchs of the Eastwere there to observe and record, even if the world-mindwas lying fallow, and no genius had been bornto inspire anew that direction of human intellect onwhich the later growth of science and civilizationdepends. With the growth of the collective mindof mankind, from generation to generation, we notethat ordered sequence of events which characterizesthe development of astronomy from earliest peoplesdown to the age of Newton, Herschel, and thepresent. It is the unfolding of a story as if with adefinite plot from the beginning.
Leaving to philosophical writers the great fundamentalreason underlying the intellectual lethargyof the Dark Ages, we only note that astronomy andits development suffered with every other departmentof human activity that concerned the intellectualprogress of the race. To knowledge of everysort the medieval spirit was hostile. But with thefounding and growth of universities, a new erabegan. The time was ripe for Copernicus and anew system of the heavens. The discovery of theNew World and the revival of learning throughthe universities added that stimulus and inspirationwhich marked the transition from the Middle Agesto our modern era, and the life of astronomy, long[12]dormant, was quickened to an extraordinary development.
It fell to the lot of Copernicus to write the secondgreat book on astronomy, "De Revolutionibus OrbiumCœlestium." But the new heliocentric or sun-centeredsystem of Copernicus, while it was the truesystem bidding fair to replace the false, could notbe firmly established except on the basis of accurateobservation.
How fortunate was the occurrence of the newstar of 1572, that turned the keen intellect of TychoBrahe toward the heavens! Without the observationallabors of Tycho's lifetime, what would themathematical genius of Kepler have availed in discoveryof his laws of motion of the planets?
Historians dwell on the destruction and violentconflicts of certain centuries of the Middle Ages,quite overlooking the constructive work in progressthrough the entire era. Much of this was of a natureabsolutely essential to the new life that was tomanifest itself in astronomy. The Arabs had madeimportant improvements in mathematical processes,European artisans had made great advances in themanufacture of glass and in the tools for workingin metals.
Then came Galileo with his telescope revealinganew the universe to mankind. It was the north ofItaly where the Renaissance was most potent, recallingthe vigorous life of ancient Greece. Copernicushad studied here; it was the home of Galileo.Columbus was a Genoese, and the compass whichguided him to the Western World was a productof deft Italian artisans whose skill with that oftheir successors was now available to construct theinstruments necessary for further progress in the[13]accurate science of astronomical observation. Evenbefore Copernicus, Johann Mller, better known asRegiomontanus, had imbibed the learning of theGreeks while studying in Italy, and founded an observatoryand issued nautical almanacs from Nuremberg,the basis of those by which Columbus wasguided over untraversed seas.
About this time, too, the art of printing wasinvented, and the interrelation of all the movementsthen in progress led up to a general awakening ofthe mind of man, and eventually an outburst inscience and learning, which has continued to thepresent day. Naturally it put new life into astronomy,and led directly up from Galileo and his experimentalphilosophy to Newton and the Principia,the third in the trinity of great astronomical booksof all time.
To get to the bottom of things, one must studyintimately the history of the intellectual developmentof Europe through the fifteenth and sixteenthcenturies. Many of the western countries were ruledby sovereigns of extraordinary vigor and force ofcharacter, and their activities tended strongly towardthat firm basis on which the foundations ofmodern civilization were securely laid.
Contemporaneously with this era, and followingon through the seventeenth century, came themeasurements of the earth by French geodesists,the construction of greater and greater telescopesand the wonderful discoveries with them by Huygens,Cassini, and many others.
Most important of all was the application oftelescopes to the instruments with which angles aremeasured. Then for the first time man had begunto find out that by accurate measures of the heavenly[14]bodies, their places among the stars, their sizes anddistances, he could attain to complete knowledge ofthem and so conquer the universe.
Copernicus, Tycho Brahe, Galileo, Kepler, Newton,all are bound together as in a plot. Not one ofthem can be dissociated from the greatest of alldiscoveries. But Newton, the greatest of them all,revealed his greatness even more by saying: "If Ihave seen further than other men, it is because Ihave been standing on the shoulders of giants."Elsewhere he says: "All this was in the two plagueyears of 1665 and 1666 [he was then but twenty-four],for in those days I was in the prime of myage for invention, and minded mathematics andphilosophy more than at any time since." All schoolchildren know these as the years of the plague andthe fire; but very few, in school or out, connectthese years with two other far-reaching events in[15]the world's history, the invention of the infinitesimalcalculus and the discovery of the law of gravitation.