IN STARRY SKIES

Evening Post, Volume CXIX, Issue 33, 8 February 1935, Page 10

IN STARRY SKIES

METEORS, FIREBALLS, AND

METEORITES

1 - (By "Omega Centauri.").

Watchers of the starry skies on any night of the year, but especially after midnight are sure to see an occasional streak of light. These luminous streaks arc mostly faint, and appear and disappear in a fraction of a second. But each tells that a speck of matter of some kind has entered the earth's atmosphere. The number of those which are bright enough to be seen with the naked eye is estimated to be several millions every twenty-four hours, and the number of telescopic ones is very much greater. They enter the earth's atmosphere at very high speeds, generally between 9 and 45 miles per second, and are consequently vaporised by friction with the air in a very short time. They appear to be of all sizes, ranging from that of the tiniest grains of sand, up-to huge masses of stone or iron weighing many tons. The,smallest ones produce only evanescent streaks of light, the' large ones produce far more striking effects. "The first we call meteors, the second fireballs. The latter frequently explode in the air, and sometimes fragments reach the ground. These •we call meteorites. When a fireball

is seen all possible .particulars should be recorded at once, and a full account sent to Mr. R. A. Mclntosh, F.R.A.S., 23 JJollywood Avenue, Epsom, Auckland' 5.E.3, who is'the Director of the Meteor Section of the • N.Z.A.S. (The journal of the R.A.S., of Canada, gave last February a very useful list of the points that should be mentioned inteporting a bright meteor. These are: 1, The. name of the observer, the place ,and time of the observation. 2. The position of the meteor, its azimuth and altitude and the slope.of its path. 3. The appearance of the meteor, its brightness, its colour! and its speed. 4. Any after-effects such as the duration and motion of any train it leaves behind it, and any sounds that are heard). If sufficient accurate observations are sent in many interesting details can be calculated with regard to the. path of the meteor,, and possibly with- regard "to ,its connection with some known meteoric swarm. J.lany records exist of .remarkable fireballs in recent years. A very fine one, on September 12, 1923, recorded part of its flight on a photograph taken by Klcpestra.at the National Observatory of Czechoslovakia. It was observed by so many people in different places that it was possible to determine its path through air. It was found that when first noticed it was at a height of 85 miles, and that after travelling fifty-five miles at the rate of 37 miles per second, it disappeared whilst still 35 miles above the ground. A fireball seen from South Africa on June 16, 1930, was visible over an area of -200,000 square miles. It travelled 655 miles at a speed of 15 miles per second.

On July 21, 1931, a fireball crossed over the Irish Sea from near the Irish Coast to the Bristol Channel. It was found to have travelled S5 miles at 12 miles h second, falling whilst doing so from a height of 44 to only 9 miles' above the water. In the B.A.A. Journal for March,l932, Mr. Mclntosh gives full details of two New Zealand fireballs. One of these was seen over Worth-eastern Otago on-July 30 1930 Reports of it were received from Dxxacdin, Oamaru, and Patearoa, the latter being 100 miles from Dunedin. The meteor is described, as dazzling and is said to have lighted up the road .like the headlights of a car. It exploded violently when about six miles above the sea, far east of Palmerston or Waikouaiti. The sound of* the ex Plosion is described as terrific and like tnunder, and one observer says that gunfire <in Trance was nothing com.pared tp it. Another fireball passed over the North Island on February 19

>lfl(J!,;t|j»velling over 90 miles iji three seeoocis, and falling only from a height of about 31 to. 25 miles. One observer records hearing a report like the discharge of a gun.

Occasionally a fireball is so large , that it is riot completely vaporised in passing'through'the air, and some portions of it reach the ground.' The majority of these are composed of stone, some of iron. Although comjparatively few: in number iron meteorites are much more frequently found, because they can be more easily i-ecog-nised. The largest stone meteorite actually seen to fail and subsequently recovered is probably the one that appeared over .Paragould in Arkansas on February 17, 1930. Independent observers in different directions, and each about a hundred miles from the place where it fell, mistook it for an aeroplane .going down in flames. At places within 70 miles of the spot •where its, wild rush ended, the detonations : attracted even more attention Jhan the dazzling light, although the was described as brighter than that of day. The meteor whilst still at a height of 18 miles seems to have burst into three parts which disappeared at heights of about five'miles above the ground. A few hours afterwards, one portion, weighing 801b, was recovered from a hole nearly three feet deep. A month- later another weighing 8201b was recovered from ,a hole 'Bft deep,;situated on a farm five miles "from that on which the first fragment t was found. A larger stone meteorite, which fell;'in Kansas, is believed to have weighed over 12001b, but it ap-

pears to have been broken on striking a ledge of rock, and the date of its fall is unknown. The resistance of .the air is so great at low levels that although most fireballs are found to have velocities of many miles per second, the meteorites when they reach the ground have speeds less than a tenth of a mile per second. .It is recorded that near Upsala in Sweden in January, 1869, when a number ofmeteorites fell, each weighing'more than a pound, several struck the ice on a lake and rebounded without damaging themselves or breaking the ice, which was only a few inches thick. Meteorites often explode and fall in scattered fragments, but it is probable that, many are travelling in groups before they encounter the atmosphere. On June 9, 1866, several'thousand meteorites fell at Khyahinya in Hungary. They were spread over an area 9x3 miles, and the largest, which weighed 647 ib, penetrated 11 feet into the ground. ' It is extremely rare for-anyone, to be, injured by a meteorite. The "Encyclopaedia Britannica" gives a list of marvellous escapes, but only one fatal accident. . The meteorite weighing 561b which fell near Wold Cottage in Yorkshire, on December 12, 1795, struck the ground ten yards from a labourer, but many others had more startling experiences. One meteorite went through the roof of a cottage, another fell beside a lady in'her garden, another close to a little girl, one between two carters on a road, and another broke'the pavement in a French town. • . -

The largest meteorite ia any museum collection weighs 36£ tons. It probably owes its undamaged condition to having fallen on snow, and therefore only partly burying itself in the bed of boulders below. It is the largest of three masses found- on • the shore of Melville Bay in Greenland. Its approximate size is 10.9 x 6.8 x 5.2 feet The greatest fall in the twentieth ceni^o waSv Probably that, of June 30 ISOB. The unusual luminosity of the sky for a couple of days was observed in Great Britain, Holland, Denmark Germany, and Austria. But little was generally known of the effects produced in. the region, where, it fell in Siberia .until 1927. Professor Kulik & fOl!! ld- that the forest ha<* been .destroyed over some hundred square miles, the trees blown down with- thedr trunks pointing radially outwards, and partly destroyed by fire, in the crater ?♦"* diStUl" bed arCa n "™* crater pits were- discovered, showing that when the meteor stuck the grounds was in many separate &£