The Birmingham age-herald., 1921-06-05
THE STARRY SKIES NV JUNE

Our map of the heavens for June has one feature of unusual interest. It has been possible for us 10 mark on the map the position of the planet Mercury. This planet Is very seldom be- yond the horizon at the time for which the maps are made. 9, p. m Mercury is often called the elusive planet" because being the planet closest to the sun, it is seldom seen far from the sun. It sets soon after the sun or rises just before the sun and hence can only, be seen in the twilight in those brief periods when it's distance from the sun is unusually large. A few days before and after June 10 constitute one such period. The sun ct this time, being far north of the equa- tor, sets late, and Mercury. being near its greatest distance east of the sun, sets at a longer interval than usual after the sun As shown OH the map. Mercury is below the well-known twin stars. Castor and Pollux, we'll to the north or west Mercury !S brighter than either of these stars. The pIanet will be very close to the ground at p. m. To see the planet one should look soon after the sun has set.
 Jupiter and Saturn are now in the Il soon be in unfavorable positions, leaving the evening sky without con spicious planets. On June 29 Mars passes the sun and becomes a morn Ing star. It is too close to the sun to be seen now. Venus Is brilliant as morning star. Summer b. gins when the sun attains it's greatest dis tance north of the equator, as it does June 21, at 6:3ofp. m.
 The Pons- Wfnnecke Comet
 The path of this interesting comet IS shown in figure 2, the Trdinary comet approaches the sun in an ap- proximately parabolic path and leaves the sun 10 return, If at all, after al exceedingly long period of time. This comet in coming toward the sun nass- ed near the great planet Jupiter so changed it's path that instead of ieav. Ing the sun it moved about the sun Tn the elliptical path shown Jupiter's ln1Iuence Is shown by the facts that the part Of the comets patcn furtherest rom the sun lies near the orbit :, Jupiter. and that the comet crosses the pianes of the earth's and Jupiters or- pits near the orbit of Jupiter Such a comet IS called periodic comet. There are apout 30 such comets, which are called Jupiter's family of comets The outer planets also have small families oI comets. This comet revolves about
 
 ana, as the figure shows, once in each period comes close to the sun and the earth. We can only see the comet in that part of its path. From B 10 F the comet is above the plane of the earlhs orbit, and elsewhere below.
 Ihe angle between the two planes is 1s degrees.
 This comet was discovered by Pons m France June 12. 1919. On March 8. leoS' Winnecke, at Bonn, Germany, olscovered comet which proved to De the same comet. Hence we call 1t the Pons-Winnecke comet. A comet was seen by Pons three days in 1908. nnis may nave been the same comet me calculations necessary to prove the identity have not been made. comet which was seen in 1766 also ap- pears likely to have been another a.. pearance of this same comet Since lS59 the comet has been known to be periodic comet and it's return has been expected at regular intervals of petWeen ? and years. The comet was seen In 1883, 1869, 1875, 1SS6 1892, 1898 lso9. and 1915. It was not seen in 1880 ana 1894 because of it's unfavora ble positions at those times
 lhe comet is periodic comet of snort period which has been seen many i times! For this reason alone it is in- teresting. It has never been con- r ~eA.io- 4SoHo or these snort < period comets are. Their many returns . 10 positions near the sun seems to < eAnaust their power to produce tails and gradually wear the comet itself away.
 The influence of Jupiter on the com cts path Is great In 1s19 for in- stance, the inclination. of the plane of the comets path to that of the earth was 10 degrees AS minutes and the 5 comets perihelion distance was 72,000,- Uoo. These quantities are now 19 de- siees minutes and 94,000.000 miles, ' resreetlvely The comet was at A. the point farthest from the sun, about An gust. 1918. At this time Jupiter was at '. This close approach to Jupiter has AHlA lHhl TIA