WHAT WILL HAPPEN.

Dominion, Volume 3, Issue 819, 17 May 1910, Page 6

WHAT WILL HAPPEN.

ABOUT COMETS' TAILS, WHY THEY POINT AWAY. FROM THE SUN. What will happen when we pass through the tail on May 19? (asks Professor S. A. Mitchell of tho Columbia University in an American paper). Will the ,cyanogen be enough to poison us?- Or if we escape will vegetation be blighted or disease be brought? Wo shall be directly in line at 9 p.m., Eastern standard time. The Japanese people will be directed towards the sun and comet and will form the central part of the bombardment of the particles of cyanogen gas. However, the modern theory of, the tails of comets tells us that though their size is enormous their weight is excessively small, and as a result the number of particles per cubic mile in the comet's tail is almost vanishing!}' small. The 'oniet of ISB2 was so situated that we could see through ten million miles of its tail, yet stars shone through it with undimmed lustre. Hence, though there may bo cyanogen gas in the tail it is there in such small quantities that could wo have a cubic mile of the tail concentrated into a glass, beaker in tho laboratory it would probably take tho greatest refinement of chemicil research to detect tho cyanogen. In addition the earth is covered over with a shell of atmosphere thousands of times denser than the comet's tail, and the particles could not possibly penetrate to tho earth's surface. An Interesting Theory. The tail of a comet always points awa\ from the sun and is more or less curved, depending on the. relative speed of tho particles that are shot oil to form the tail, and of the comet in its orbit. A splendid theory explaining the apparent negation of gravitation in comet's tails pointing away from the sun has lately been developed by the Swedish scientist Arrhonius. According to him the particles of the tail are excessively small, and they are driven from the sun by pressure of the sunlight'. In addition a new tail is continually being formed tho old material is loft behind in spaca and the comet is alowly

wasting away. The rarity of the tail may bo imagined when we realise that Halley's Comet lias lasted as we know for 2000 years, and still is not consumed. Although the comet will pass directly across the face of the sun on May 10, it is questionable if even an astronomer will be able to see the transit, and although we shall be enveloped in the tail for somo hours and shall be bombarded by cometary material wc probably shall be totally unaware of it, for the cometary particles are so small that probably not oven a meteor shower will take place. Indeed, so little of an unusual nature will occur that nothing would be known of it weTO it not for the calculations of tie astronomer. Wo Have Done It Before. The earth has more than once before passed through tho tail of a comet; it happened last in 1861, but no one was sure that anything unusual was observed. However, May 1!) will be a memorable day to the astronomer mid all the refinements of modern science will be cmployed. Meanwhile the comet, as it gets closer to the sun, is getting brighter and the tail is increasing in length. On February 3 Professor' Barnard estimated the length of tail on the photograph at 5,000,000 miles, while on February 27 this had increased to 14,000,000, and! this almost two months before the comet is closest to the sun and most active! The modern camera with the sensitive plate in the skilful hands of a great man like Professor BarnaTd will bring to us photographs of matchless beauty showing the many and varied changes taking place in the tail, while the spectroscope will help solve many perplexing questions of interest to the astronomer. From the length of the tail before passing through tho sun it*'seems almost certain that Halley's Comet will be such a magnificent spectacle that a quarter century hence we will tell our grandchildren about the great comet of 1910. Previous Appearances. As Halley's was the first periodic comet to be observed, the scientific interest in it has been very great, and previous visits to the earth have been caTefully investigated. As is given in the following table, authentic returns of the comet date back without a break to the year 11 B.C. Even 225 years -previous there was a comet observed that was undoubtedly Halley's, but tho records are not absolutely conclusive. The dates give the time of perihelion passage, or ■ the time when the comet was nearest tho sun, and instead of placing the day and month of the year the times aTe. expressed in decimals of a year, 1910.3 meaning that tho comet came to perihelion three-tenths of a year after the first "of January. The past appearances of the comet most worthy of note are those of 1066 and 1456. In the former year William of Normandy came over to England, and the Bayeux tapestry gives a representation of the popular belief of the connection of tho comet with the conquest of England and the death of Harold. Interval Interval Tear, in years. Tear, in years. B.C. 11.8 ... A.D. A.D. 989.7 ... 77.5 66.0 ... 77.8 1006.2 ... 76.5 141.1 ... 75.1 1115.3 ... 79.1 218.2 ... 77.1 1222.9 ... 77.6 295.2 ... 77.0 1301.8 ;.. 78.9 373.8 ... 78.6 1378.8 ... 77.0 451.5 ... 77.7 1456.4 ... 77.6 530.8 ... 79.3 1531.6 ... 75.2 607.3 ... 76.5 1607.8 ... 76.2 684.8 ... 77.5 1682.7 ... 74.9 760.4 ... 75.6 1759.2 ... 76.5 837.2 ....76.8 1835.8 ... 76.7 912.2 ... 75.0 19NU ... lUb VIEWED FROM CAPE PALLISER. Mr. Hansen telegraphs as follows from Cape Palliser Lighthouse:—"Magnificent view of comet this morning. The tail subtended an angle of 90 degrees; nucleus same magnitude and a little brighter than Saturn. Visible to the naked eye till 6.30. People having .clear easterly view should look out between five and six to-morrow morning, and may then see it." SEEN ON CORINTHIC. ALL THE WAT -FROM CAPE TOWN. "She came up over the port bow regularly every morning, and as the weather kept pretty clear throughout wo were never without our 'coffee and comet,'" said an officer of the Corinthic, which arrived from London via South Africa and Hobart yesterday afternoon. The sight of the great comet rising clear and clean out of the southern ocean is said to have been a particularly brilliant one, and those in Wellington who saw the oomot yesterday morning can have no doubt as to the beauty and impressiveness of the sight. • The ship's report, always a very stiff and forniaK document, records that "an inteiestiug observation made during the voyage was Halley's comet, which has been visiblo each.morning at about sunrise since leaving Cape Town, sometimes the corona, shining very distinct and bright." THE SUN AND THE COMET. On May 19 the comet will pass across the sun's disc between 1.50 and 2.50 pju., and after that date will appear in the western sky after sunset. Distance of Cometfrom the Earth. Comet Sun Millions Date. rises, rises, of miles a.m. a.m. May 17 -.. 5.17 6.52 18 May 18 5.58 6.53 16 May 19 6.49 6.54 15 Distance of" Comet from the Earth. Sun Comot Millions Date, sets. sets, of miles. p.m, p.m. May 20 _- 4.39 5.48 14 May 21 ~ 4.38 6.52 15 \ May 22 .... 4.37 . 7.33 16 Mav 23 4.3G 7.55 18 May 24 4.36 9.27 ' 21 May 25 4.35 10.0 24 May 26 '. 4.35 10.19 27 May 27 4.33 10.22 30 Mav 28 4.33 10.33 34 May 29 4.32 10.38 37 . May 30 4.32 10.44 41 NO FEAR OF EVIL CONSEQENCES. Sir Robert Ball on March 8 bade a crowded audience in the new Examination Hall at Cambridge have no fear of evil consequences from the visit of Halley's comet and our being immersed in its tail. Those who were alive in 1861 spent a couple of hours in a comet's tail and none was the worse for it. The only person ho had heard of who suffered was a clergyman, who had to light a couple of candles to see by because of the mistiness of the atmosphere. Nor need there be any fear of collision, although Halley's comet was contravening all the traffic regulations of the solar system.