ASTRONOMICAL

New Zealand Times, Volume LIII, Issue 12395, 15 March 1926, Page 12

ASTRONOMICAL

N.Z. ASTRONOMICAL SOCIETY INTERESTING AND INSTRUCTIVE NOTES Special to “N.Z. Timea” by “Alpha Centaur'i” (Contributions to these colums should be addressed to the Society, Dominion Observatory, Wellington.)

PHENOMENA FOR APRIL, 1926 N.Z.M.T. <l. h. m. 2 14 31 Saturn conj. Moon S. 3 13 15 Antares coni. Moon S. 6 OS 20 Moon .at last quarter. SO4 OS Mars conj. Moon N. 18 43 Jupiter conj. Moon N. 9 12 52 Venus conj. Moon N. 11 (4 41 Uranus conj Moon N. 13 52 Mercury conj. Moon N. 13 00 20 Full Moon. 15 06 10 Sunrise at Auckland. OG 20 Sunrise at Wellington. 00 31 Sunrise at'Christchurch. 00 43 Sunrise at Dunedin. 17 22 Sunset at Wellington. 17 27 Sunset at Auckland. 17 27 Sunset at Christchurch. 17 33 Sunset at Dunedin. 17 50 Castor on meridian. 17 55 Procyon on meridian. 18 01 Pollux on meridian. IS 49 Satnrn rises. 13 58 Antares rises. 19 41 Areturus rises. TO 55 Aldeharan sets. 20 23 Regulus on meridian. 21 38 Castor sets. 21 47 Betelgueso sets. 22 02 Rigol sets. 22 12 Pollux sets. 22 41 Alpha Cruois on meridian. 23 37 Procyon sets. 23 40 Spiea on meridian, i 23 51» Aeliornnr on meridian below pole. 10 10 20 Aldeharan conj. Moon S. 1J 00 30 Venus at greatest elong. "W., a morning star in Aquarius. 23 13 Pollux coni. Moon N. 20 10 53 Moon at first quarter. 22 07 40 Neptune conj. Moon S. 2! 03 Regains conj. Mann S. 23 22 17 Mars conj. Jupiter, Mars S. 27 <T3 53 Soma eonj. Moon S. 28 II 47 Full Moon. 17 3> Mercury at greatest elong. W., a morning star in Pisces. 29 17 59 Saturn conj. Moon S. 30 13 15 Antares conj. Moon S. SUNSPOTS, JANUARY, 1926 Note. —Detailed positions of sunspots trill not he published in these notes in future; but accurate records are still being kept, and those desiring further information should apply to the Dominion Observatory, Wellington. The year 1926 commenced with a large and active group nearing the Sun's western limb. This disturbance (No. 126 of 1925) was in latitude 24 deg. N., and had disappeared round the limb by January 4th. Spots of moderate size were recorded from the 4th to the 15th of the month, the predominance being in the northern hemisphere On the 19th two large spots were observed to eastward of the central meridian, one in lat. 22 deg. N., the other in lat. 30 deg. S. These remained conspicuous objects tuitil about January 28th, when the Sun's rotation carried them out of sight. On the 28th another large spot had entered the Sun’s disc in lat. 37 deg. S.

LIBRARY REPORT (Continued from list published in the notes for February, 1926.) Smithsonian Miscellaneous Collections, Vol. 77, Nos. 5,6, 7—papers on Solar Radiation anti Weather. Reprint from the-Monthly Notices of the Royal Astronomical Society for June, 1923—" A Modification of Gauss's Method for tho Determination of Orbits." The Observatory, Oct., Nov. and Dec., 1925, also duplicate copy of April, 1925. J/Astronomic, Oct., Nov., 1925. Popular Astronomy, Nov., Dec., 1925, and Jan., 1926. Bulletin do l’Observatoire de Lyon, Nov., Dec., 1925. Monthly Notices of the Royal Astronomical Society, Vol. 85. Nos.. 1,2, 3, 4 and 5 (1924 Nov. —1925 March). Publications of the Dominion Observatory, Canada, Vol, 9, No. 3- (Astrophysics). Astronomic Determinations (U.S. Coast and Geodetic Survey). Nautical Almanac, 1926, 1927 (presented by the Admiralty). New South Wales Bulletin, Nos. 31, 32 (Dec., 1925, Jan., 1926). Publications of the Lick Observatory, Vol. 15 (1925) —Meridian Circle Observations. N.Z. Surveyor, Vol. 12, No. 10 (Dec., 1925). Monthly Record of Meteorological Observations (Canada), March, 1925. "Long Period Variables" from the W. H. Smart Observatory. THE APPEARANCeTf METEORS (By R. A. Mclntosh, Hamilton, N.Z.) We have already dealt with the methods employed in observing meteors, and it is fitting that we should devote a little, time to the characteristics of individual meteors before passing to the more theoretical side of the subject. The position of the radiant influences in a remarkable degree the appearances of individual meteors emanating from it. If the radiant is within 50 deg. of the meteoric apex (90 deg. preceding the sun on the ecliptic) tho meteors, especially the brighter ones, leave streaks. They ore usually white, showing a high degree of incandescence. If the radiant is near the anti-apex, or in that hemisphere, the meteors are streakless, travel slowly and often leave trails of yellow sparks. A radiant near the horizon gives longpathed meteors of slow speed having a flaky appearance. Radiants which are nearly vertically overhead give short, darting meteors with dense streaks or trains. Tf the meteor is close to the radiant its track is usually slow and appears greatly foreshortened hv effects of perspective. ft is travelling nearly in tho line of sight and any streaks or offcome of sparks is dense because it is seen through the whole depth. Such meteors often have curved paths of 2 deg. to 4 deg. in length. Meteors at great apparent distances from their radiant travel in long pallia with great apparent" velocity, leaving little or no streaks in their wake. These deductions have been rnado by W. F Denning, the noted English meteor observer, from his own extensive observations. The actual velocity of indoors is affected by the direction in ■which they are travelling through apace. The greatrst velocity is attained when the meteors moot the earth, travelling in Hie opposite direction to it. Without going into mathematics assume "MV equals the velocity of tho meteor shower, RV ,equals the velocity of Urn earth in its'‘orbit, and V equals the individual meleor’.s nppa/vnt, velocity. Tn the case mentioned V equals MV plus KV. This is Ihe ca-o where the actual velocity reaches a maximum. The Leonids (November; Miower is an illustration of this ea«n. the minimum velocities occur when the earth and meteor stream are travelling in the same direction, and one overtakes tlie other. Whore the earth is overtaken bv the mdoor stream V equals MV minus BV, n.s in the oa* o of tho Amlrornedes (November) shower. Where the earth overtakes a meteor stream the velocity is also very low. In this case V equals KV minus MV. These extreme cases serve to explain the effect of orbital motion on the meteor’s velocitv The following tables taken from ove--6000 observations mafic by Dr. C. 1\

Olivier, are intended to give an indication of tho colours and magnitudes of the majority of meteors. Colours, 36.7 per cent, red; 17.2 per cent, orange; 15.4 per cent yellow; 19.1 per cent, green; 1.6 *per cent. blue; 0.9 per cent purple; 9.1 per cent, white. The terms "yellow" and "orange" were in most cases interchangeable. Blue, purple and green were difficult to distinguish from white unless bright or slow. Very few meteors below the third magnitude showed any colour. These results were obtained from 2010 meteors which had their colours recorded. The remaining 4000 should have been added to the _ percentage of white meteors, as white is the absence of any particular colour. Magnitudes.—Brighter than om. 1.3 per cent. Om. 1.1 per cent., lm. 2.9 per cent. 2m. 10.2 per cent., 3m, 29.4 per cent., 4m. 30.5 per cent., sm. 16.3 per cent., 6m, 2.3 per cent., fainter than Cm, 0.3 per cent. These results were obtained from ISB9 meteors observed at Lick Observatory, and it was found by Dr. Olivier that tho clearer sky was responsible fo* a great increase m meteors of the fourth and fainter magnitudes. At the McCormick Observatory third magnitude meteors were in the majority, whereas in tho clearer skies at Lick fourth magnitude meteors abounded. Dr. Olivier believes that faint meteors are far more numerous than bright ones, were our skies clear enough to observe them. The series representing meteor magnitudes is similar to that of stars, except that tho factor seems to bo less than 2.5. Exceptional meteors, including those which are stationery, variable in magnitude, with curved or irregular paths, and remni # -able trains, are very rare. (To be continu'ed.)