The Astronomy of Milton's 'Paradise Lost', Thomas Nathaniel Orchard [best selling autobiographies .TXT] 📗
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Galileo did not afford his opponents much time to oppose or controvert with argument the discoveries made by him with the telescope before his announcement of a new one attracted public attention from those already known. He, however, exercised greater caution in disclosing the results of his observations, as other persons laid claim to having made similar discoveries prior to the time at which his were announced. He therefore adopted a method in common use among astronomers in those days, by which the letters in a sentence announcing a discovery were transposed so as to form an anagram.
Galileo announced his next discovery in this manner, and which read as follows:—
This, when deciphered, formed the sentence:—
Galileo perceived that Saturn presented a triform appearance, and that, instead of one body, there were three, all in a straight line, and apparently in contact with each other, the middle one being larger than the two lateral ones. In a letter to Kepler he remarked: ‘Now I have discovered a Court for Jupiter, and two servants for this old man, who aid his steps and never quit his side.’ Kepler, who excelled as an imaginative writer, replied: ‘I will not make an old man of Saturn, nor slaves of his attendant globes; but rather let this tricorporate form be Geryon—so shall Galileo be Hercules, and the telescope his club, armed with which he has conquered that distant planet, and dragged him from the remotest depths of Nature, and exposed him to the view of all.’ Continuing his observations, Galileo perceived that the two lateral objects gradually decreased in size, and at the expiration of two years entirely disappeared, leaving the central globe visible only. He was unable to assign any reason for this peculiar occurrence, which caused him much perplexity, and he expresses himself thus: ‘What is to be said concerning so strange a metamorphosis? Are the two lesser stars consumed after the manner of the solar spots? Have they vanished and suddenly fled? Has Saturn, perhaps, devoured his own children? Or were the appearances, indeed, illusion or fraud, with which the glasses have so long deceived me, as well as many others to whom I have shown them? Now, perhaps, is the time to revive the well-nigh withered hopes of those who, guided by more profound contemplations, have discovered the fallacy of the new observations, and demonstrated the utter impossibility of their existence. I do not know what to say in a case so surprising, so unlooked-for, and so novel. The shortness of the time, the unexpected nature of the event, the weakness of my understanding, and the fear of being mistaken, have greatly confounded me.’ After a certain interval those bodies reappeared; but Galileo’s glass was not sufficiently powerful to enable him to ascertain their nature nor solve the mystery, which for upwards of half a century perplexed the ablest astronomers.
The elucidation of this inexplicable phenomenon was reserved for Christian Huygens, who, with an improved telescope of his own construction, was able to declare that Saturn’s appendages were portions of a ring which surrounds the planet, and is everywhere distinct from its surface.
Galileo next directed his attention to the planet Venus, and as a result of his observations was led to communicate to the public another anagram:—
This, when rendered correctly, reads:—
The phases of Venus were one of the most interesting of Galileo’s discoveries with the telescope. When observed near inferior conjunction the planet presents the appearance of a slender crescent, resembling the Moon when a few days old. Travelling from this point to superior conjunction, the illumined portion of her disc gradually increases, until it becomes circular, like the full Moon. This changing appearance of Venus afforded Galileo irresistible proof that the planet is an opaque body, which derives its light from the Sun, and that it circles round the orb—convincing evidence of the accuracy and truthfulness of the Copernican theory.
It was in this manner that Galileo announced his discovery of the phases of Venus, the peerless planet of our morning and evening skies, whose slender crescent forms such a beautiful object in the telescope, and who, as she traverses her orbit, exhibits all the varied changes of form presented by the Moon in her monthly journey round the Earth. These varying aspects of Venus were not unknown to Milton; and, indeed, he may have been informed of them by Galileo in his conversation with him at Arcetri; nor has he failed to introduce an allusion to this beautiful phenomenon in his poem. In his description of the Creation, after the Sun was formed, he adds:—
Repairing, in their golden urns draw light,
And hence the morning planet gilds her horns.—vii. 364-66.
Galileo also discovered that the planet Mars does not always present the appearance of a circular disc. When near opposition the full disc of the planet is visible, but at all other times it is gibbous, and approaches nearest to that of a half-moon when at the quadratures.
In the year 1610, on directing his telescope to the Sun, Galileo detected dark spots on the solar disc. Similar spots, sufficiently large to be distinguished by the naked eye, had been observed from time to time for centuries prior to the invention of the telescope, but nothing was known of their nature. In 1609 Kepler observed a spot on the Sun, which he thought was the planet Mercury in conjunction with the orb; the short time during which it was visible, in consequence of clouds having obscured the face of the luminary, prevented him from being able to determine the accuracy of his surmise, but since then it has been ascertained that no transit of Mercury took place at that time, and Kepler afterwards acknowledged that he had arrived at an erroneous conclusion. Galileo was much puzzled in trying to find out the true nature of the spots. At first he was led to imagine that planets like Mercury and Venus revolved round the Sun at a short distance from the orb, and that their dark bodies, travelling across the solar disc, gave rise to the phenomenon of the spots. After further observation, he ascertained that the spots were in actual contact with the Sun; that they were irregular in shape and size, and continued to appear and disappear. Sometimes a large spot would break up into several smaller ones, and at other times three or four small spots would unite to form a large one. They all had a common motion, and appeared to rotate with the Sun, from which Galileo concluded that the orb rotated on his axis in about twenty-eight days. Galileo believed that the spots were clouds floating in the solar atmosphere, and that they intercepted a portion of the light of the Sun.
The Milky Way, that wondrous zone of light which encircles the heavens, remained for many ages a source of perplexity to ancient astronomers and philosophers, who, in their endeavours to ascertain its nature, had arrived at various absurd and erroneous conclusions. On directing his telescope to this luminous tract, Galileo discovered, to his inexpressible admiration, that it consists of a vast multitude of stars, too minute to be visible to the naked eye. He also discerned that its milky luminosity is created by the blended light of myriads of stars, so remote as to be incapable of definition by his telescope. In his ‘Nuncius Sidereus’ he gives an account of his observations of the Galaxy and expresses his satisfaction that he has been enabled to terminate an ancient controversy by demonstrating to the senses the stellar structure of the Milky Way. When engaged in exploring the celestial regions with his telescope, Galileo observed a marked difference in the appearance of the fixed stars, as compared with that of the planets. Each of the latter showed a rounded disc resembling that of a small moon, but the stars exhibited no disc, and shone as vivid sparkling points of light; all of them, whether of large or small magnitude, presenting the same appearance in the telescope. This led him to conclude that the fixed stars were not illumined by the Sun, because their brilliancy in all their changes of position remained unaltered. But, in the case of the planets, he found that their lustre varied according to their distance from the Sun; consequently, he believed they were opaque bodies which reflected the solar rays. On directing his telescope to the Pleiades, which, to the naked eye, appear as a group of seven stars, he succeeded in counting forty lucid points. The nebula Praesepe in Cancer, he was also able to resolve into a cluster of stars. Galileo made many other observations of the heavenly bodies with his telescope, all of which he describes as having afforded him ‘incredible delight.’
Shortly before the failure of his eyesight, Galileo discovered the Moon’s diurnal libration, a variation in the visible edges of the Moon caused by its oscillatory motion, and the diurnal rotation of the Earth on her axis.
Though Milton has not favoured us with any interesting details of his interview with Galileo, nor expressed his opinions with regard to the controversies which at that time agitated both the religious and scientific worlds of thought, and which eventually culminated in a storm of rancour and hatred that burst over the devoted head of the aged astronomer, and brought him to his knees, yet he informs us that he ‘found and visited’ Galileo, whom he describes as ‘grown old,’ and cynically remarks that he ‘was held a prisoner of the Inquisition for thinking in astronomy otherwise than the Franciscan and Dominican licensers thought.’ Milton does not allude to his blindness, and yet it would be natural to imagine that, had his host suffered from this affliction at the time of his visit, he would have referred to it. We learn that Milton arrived in Italy in the spring of 1638. In 1637, the affection which, in the preceding year, deprived Galileo of the use of his right eye, attacked the left also, which began to grow dim, and in the course of a few months became sightless; so that, although Milton has not alluded to this calamity, Galileo had become totally blind at the time of his visit.
How much Milton was impressed with the fame of Galileo and his telescope becomes apparent on referring to his ‘Paradise Lost.’ In it he alludes to the instrument upon three different occasions, twice when in the hands of Galileo; and the remembrance of the same artist was doubtless in his mind when he mentions the ‘glazed optic tube’ in another part of his poem. The interval that elapsed from the date of Milton’s visit to Galileo in 1638, to the publication of ‘Paradise Lost’ in 1667, included a period of about thirty years, yet this length of time did not erase from Milton’s memory his recollection of Galileo and of his pleasant sojourn at Florence.
The first allusion in the poem to the Italian astronomer is in the lines in which Milton describes the shield carried by Satan:—
Hung on his shoulders like the Moon, whose orb
Through optic glass the Tuscan artist views
At evening, from the top of Fesolé,
Or in Valdarno, to descry
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