SCIENCE UP TO DATE
MISCELLANEOUS RECENT ASTRONOMICAL DISCOVERIES. . [By James Collier.] XCIX. (Special Rights Secured by the ‘Star.’) Some stars “ swim into the ken ” of a “watcher of the skies.” Of these were the “non' stars” that rather blazed than swam into tho ken of Tycho Brahe and Dr T\ C. Anderson; and tho minor planet CcTcs'iiwam into the observation of Piazzi. But in general a star or a planet is first 4een by someone who is looking, for it or is looking for something else. Neptune was chased and run to sky by two mathematical astronomers, but Uranus was found by an astronomer who wan looking “at lairge,” as tho Scots laird swore. So have tho minor planets been specifically tracked, tho scent consisting of a guiding law that bore them in its bosom. —Bode’s Law.—
Concisely stated, this law, which was first formulated by Titius, of Wittenberg, lays it down that the planets of our system arcs separated from tho sun by an increasing sum amounting to double the distance of the next innermost planet. When it was confirmed by Herschel’s discovery of Uranus, which was found to bo at double the distance of the orbit of Saturn, general confidence was felt in it, and it sank into the minds of astronomers as a datum or first principle. But it was noticed that between Mars and Jupiter there was a gap. Does there not revolve an undiscovered planet in the vast intervening space? asked a young Berlin astronomer named Bode. He had, indeed, asked himself the question before tho discovery of Uranus, and for 15 years he was on the lookout for such a planet. In 1800 he got together a baud of six observers, who mapped out the zodiac into 24 zones. While these astronomers were having their respective shares assigned to them, they were startled to learn that the Italian astronomer Tiazzi, of the'observatory at Milan, had accidentally trapped tho missing planet. He was not “ out,” as American and now Australian politicians say, to discover the planet. He had gone, like .Saul, to seek his father’s asses, or to make a fool of a brother-astronomer, and ho came back with a new planet in his possession. —A Lost Planet.— Having been discovered on January 1, 1801, it was the first planet of the century, as Heine falsely pretended to be, on tho same terms, one of tho first men of the century. For six weeks he watched it, when ho became seriously ill. He had written in good time to Bade at Berlin and Oriani at -Milan, but in those times it took 56 days for a letter to reach Berlin, and (very strangely) 72 days for a letter to reach .Milan. Unfortunately, both letters arrived too late. The planet seemed to he gone beyond recall. It had travelled too closely to tho sun to be discovered through the telescope. —Rediscovered.— Piazzi had made a few observations, but they were very incomplete; they covered an'arc of only throe degrees. No, not from calculations so based~at least, with the ordinary methods—could the orbit of the tiny planet be ascertained, and for nearly a year it was lost to sight. Nothing less than a new mathematical method would avail. Tho great German mathematician of the day—one of the greatest of all time—Gauss, of Goettingen, then devised a method capable of grappling with such a problem, and expounded it in his 1 Theory of Motion,’ which at once enabled the truant to be discovered. Recording to Gauss himself, tho method was first applied in October, 1801, and the first clear night afterwards the mite of a planet was found. In reality (and tho two statements are not necessarily inconsistent) it was rediscovered by Von Zach at Gotha (using Gauss’s method) on the last day of tho year, as it had been discovered by Piazzi on tho first day of the year. Next night it was rediscovered afresh by Olbora at Bremen, who had eagerly searched for it through months. Never again could it be lost. —Pallas.— How account for the existence of planets so insignificant in size? By discovering* others as tiny. Olbers conceived that. Ceres and its possible comrades were the fragments of a largo planet that had exploded in mid-sky. As all bodies that revolve around the sun necessarily comeback periodically to their starting point, these planetary fragments would return to tho. place where the explosion had happened. Directing his telescope to that quarter of the heaven®, Olbers in 1802 found a second planetoid, which ho- named Pallas. Two years later (in 1804) Juno was discovered by Harding, and five years later (in 1307) Olbers added Vesta- to tho list of minor planets. For nearly 40 years no others wore found, and it gradually came to be believed that no more would be discovered. Not so did Herr Hencko believe (an cx-postmaster of Driessen, in Prussia), who had sought, for others for 15 years, and at last, in 1845, found Aslrtea. and in 1847 discovered Heho. In the same year as marked the discovery of Hebe Mr Hind, tho observer of an amateur residing near I-ondon, discovered Iris (a name suggested by Sir John llorschel) and Flora. Year by year others were added, till the number exceeded 500. New planets were cheap, but their names were dear. Millionaires paid handsomely tc have the honor of naming them. —Photography and Astronomy.—
The labor of searching for planets or planetoids has for many years been taken off the shoulders of astronomers and thrown on the back of. the camera. On this new star-trap and planet-trap each fixed star leaves its mark, and each planet, being in motion, makes its small trail. The new planet can thus bo at once do tcctcd. and it is by this agency that most new planets,' novee (or “new” stars), and returned or new comets have been discovered. Mrs Fleming, of the Observatory at Harvard, thus discovered a nova in Perseus in 1887, and five others at later dates. .She was, however, the first and only person who has found “ now stwira ” by photography, till Professor Turner found Move Oeminorum at Oxford in 1903. All were, m a manner, accidental, save those of Mrs Fleming, who made a deliberate search for “new stars” among the plates of the Observatory. Photography has not, indeed, entirely superseded telescopic or unarmed observation. Dr Anderson, the discoverer of the second 1 nova in the constellation Perseus, rarely used a telescope, of tenor a field glass, and generally the 'naked eye. On a fine night he sat at his open study window, and surveyed the outstretched heavens. There, as already told in these columns,' he was startled by the first nova of the century —a. worthy comrade of the planet Ceres, discovered exactly .a century earlier. —Some Now Points.— In an article published some months ago tho application of photography to astronomical discovery was described, but a few new points may he added. Tho pioneer of astronomical photography was Dr Common, of England. It jvas not at first adopted by tho French, but the French astronomer Chacornac initiated a series of star maps round tho Zodiac, but still used tho method of ocular, observation. So. at first, did the French brothers, Paul and Prosper Henry, huj when they sought to overcome the obstacles arising from the Zodiac's crossing the Milky Way they were swamped by the difficulty of the task. They then heard of Sir David Gill’s photographs of the comet seen at the Capo in 1882, and incidentally of stars, nor were these the first, and they applied the method to map the stars, and not only the Zodiac. Then came tho International Conference of 1887, held to prepare an astrographic chart. At a second conference tho Henrys’ very imperfect refracting instruments were recommended for adoption, though Professor Pickering, of Harvard, advised the adoption of the reflector. Eighteen observatories had, or were able to procure, the necessary funds. Two were Australian —Sydney and Melbourne. Tt was arranged that Melbourne should j.-ikp exactly the same; number pf puhto-.
graphic plates as London, or 1,149, while Sydney was to take ao fewer than 1,400* and the Cairo as many as 1,512. Oxford was to take 1,180, and Professor H. H Turner gives an account of the work there done. There in. 1903 they found the last nova as yet, Nova Geminoruni. lyi’.en the 18th new star blazed up it illuminated a surrounding dark nebula- Not till months after did the illumination reach portions of the nebula.. When did this happen? Hundreds or thousands of years ago, and it is otill doubtful whether tho nova caused the outburst.
—Migrations of Stars. —
Some month or two since, in a biographical sketch of Sir. W. Hersehel, .it was mentioned that a remarkable covery had been made by Professor Kapsteyn, who divided tho great mass of bright stars into two groups that fly through one another. A kindred discovery has since been made by Professor Less, who has found a particular immense group of stars in the constellation Taurus “ moving in parallel lines like a flock of migrating birds.” Such, like tire other, is a discovery due to the spectroscope, _ and thetdistance, shape, and dimensions of tho cluster have hmr ascertained. For it is moving just over our heads. One member of the cluster is quite “dose to our sun.’’ That is Birius, and so “close'” is it that it is only a trifle of three or (our “light years” from him. To compute the distance that light travels in a year is a task for an astronomer, but even thrice that stupendous distance is a jest to tire actual dimensions of tho cluster,” which is said to measure about 100 light years' from end to ond. Still another such migratory movement is announced, in a class of stars belonging to a particular specific type—class B spectrum—and they ore (or were) supposed to be travelling with a common motion of 10 kilometres a second. The alleged discovery was based on observations made at the Yerkes Observatory, and it is now doubted by the director of that observatory—Mr Campbell, who asserts that the conclusion is vitiated by “ the existence of a systematic error in the observations.” It was a case of tho Hnxleyan bathybius over again—a mare’s, a fish’s, or a star’s nest.
Quite lately Mr W. W. Campbell, of the Lick Observatory, hae found that the sun and his planets are journeying Lyraward at- the rato of two-thirds of the velocity of the earth in its orbit, or sufficient to carry the solar system 350 millions of miles in a year. —Sunspots.—■
Wo lately stated the law of sunspots as formulated by Schwabe. Professor Arthur Schuster, of Manchester, has now overhauled the observations and figured them differently. A cycle of lli • years was believed to be the corrected amount of tho variation, but Prof. Schuster (one German correcting another) found that there were other periodicities. Besides the main cycle there are periodicities of 4, 8, and 14 years; and the 11 years’ cycle is not continuous, but in the 18th century it occurred more frequently than tho 8-year or the 14-year cycles. So much for an accepted formula. A guess or two have been made regarding tho cause of sunspots. As the Leonid meteorswarm revolves in 55 years, and as several of the sunspot-periodicities are harmonics of a period of 55 years, there is a possible relationship, and that may one day be established. Again, Prof. E. W. Brown suggests that the cycle of 11 years was determined by the tidal action of Jupiter as periodically affected by two causes. As effected by tho eccentricity of Jupiter, if is prolonged to nearly I*2 years; as affected by tho motion of Saturn, to almost 10. But Prof. H. H. Turner gives reasons for doubting the conclusion. Tho explanation does not account for any other periodicities than tho 11-year cycle.
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SCIENCE UP TO DATE, Evening Star, Issue 15644, 7 November 1914
SCIENCE UP TO DATE Evening Star, Issue 15644, 7 November 1914
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