THE HEAVENS IN JULY

Evening Star, Issue 19290, 1 July 1926, Page 13

THE HEAVENS IN JULY

, PLANETS AND ‘G6HSTELLATIOHS [By the Director Wanganui Observatory.] ■—The Sun—■ i! 1 constellation Gemini till the 20th, when ho makes his entry into Cancer. Having reached his greatest northern declination on the 22nd of last month, his movement is ngain to--1 wards the south, giving him a greater altitude in our latitudes by 6.6 degrees, nearly, during the month. Sunspots, though not of great proportions', have been fairly plentiful during the past month ? and should be looked for at this time, a great disturbance being likely at any time during this period. A partial eclipse of the sun will take place on, the 10th. _ It is annular in the Northern Hemisphere, and, although visible in Northern Australia, will _ not be seen in any part of- this dominion. * —The Moon- ' moving night by night amongst the stars, apparently towards the east, passes the various bodies visible to us, and serves as a convenient pointer to them. She will bo nearest Mercury on the evening of the 12th, Venus on the morning of the 7th, Saturn on the nights of the 20th and 21st, Jupiter on the nights of the 26th and 27th, Mars on the 3rd and again on the last day of the month. —Mercury—is an evening star at the beginning of the month, and attains his greatest elongation east on the 11th, when he is over_26deg from the sun, and is an evening star, easily visible shortly after sunset. Ho is in aphelion on the 19th, and stationary amongst the stars on the 24th. He will be in lunar conjunction on the 12th. —Venus—• is a morning star during the month, moving through Taurus and Gemini, towards the east. She will bo iu conjunction with the moon on the morning of tha 7th, about I.sdeg north of the moon, when she may easily bo picked up by the naked eye in full daylight. —Marais a morning star, in Pisces, at the beginning of the month, rising just after midnight. He becomes an evening star iu the early days of the month, and may be observed in the early morning hours, but still too distant to be of much use to any but the possessors of very large telescopes. His distance from the earth on the loth is about ninety-one millions of miles. He is in lunar conjunction on the morning of the 3rd, and again on the last of tha month, and will bo in perihelion on the 19th. • —Jupiter—i is an evening star during the mouth, rising at 9 p.ra. during early days of July, and being unmistakable by reason of his great brilliancy at this time. The varied detail of his “ Bolts ” will well repay the observer at this time, being the possessor of a good telescope, and giving the planet anything more than 30deg of elevation- under good seeing conditions. He will he in lujiar conjunction on the morning of the 27th. —Saturn —• is an evening star, being high in the eastern sky at sunset, and making a triangle with the stars Alpha and Beta of Libra, Saturn to the right, or south. His ring system is now well worthy of careful scrutiny on any fmo morning by those interested in the beautiful which space is prepared to reveal in a good telescope. PLACES OF CONSTELLATIONS. The constellations are given below as they may be seen in the sky at 9 p.m. of the Ist, 8 p.m. of the loth, and 7 p.m. of the 30th. Looking due north, we see, nearest the horizon, Hercules on the right and Bootes on the loft, with the. Northern Grown between these and just passing the meridian. Over Hercules is Ophiuchus and Serpens. Working round towards the east, we find Lyra just rising, the brilliant Vega being well above the horizon at this time. Cygnus is just emerging over the north-east, its fine star, Beta, or Albireo, the beak of tho*Swan, being a beautiful double star, the components of which are green and yellow. Aquila lies well up, and over Cygnus, and under the more eastern part of the Eagle may be seen tho Dolphin. Aquarius is just coming up duo east, and abovo this may bo seen Capricornus and Sagittarius, with tho Scorpion reaching up to the zenith. Over the south-east is Gras, the Southern Crane, with Pisces and Indus. _ Looking due south Eridanus and its fine star Achernar is seen low down to the left of the southern meridian, while the more brilliant Canopus, the lucida of _ the Ship, Argo, is at about equal .distance from tho meridian "towards tlic right. Mydims and Toucan are higher and east of the meridian, while Pavo and the Southern Triangle, with the Altar, Ara, is nearer the zenith. By this time wo find tho Southern Cross has turned in the sky, and may now bo seen declining to the west from its highest over the Polo, followed by the pointers of Centaurus, Alpha and Beta. The fine stars of Argo are in a bunch over the south-west and embedded in the Milky Wav, which at this time reaches from N.IJ. to S.W. Hydra, the Water Snake, is now seen with its head buried beneath the western horizon, the ''two small constellations of Crater and Corvus. The last of Leo is seen in the western sky, - followed by Virgo and Libra. OBSERVATIONS OF THE SUN. To Dr Georgo E. Halo and his body of indefatigable workers, backed up by the generous assistance of various wealthy patrons of astronomy, wo are indebted for a steady and continuous advance in our knowledge of the sun. Everything possible to ensure the best results has been effected at this station. Great towers of skeleton jonn in stool, rising to a height of 75ft and 160 ft above the earth’s surface, cany on their tops domed structures containing louses and mirrors, wherewith the sun is brought down to a focus in a pit dug deep down, into ■ the earth. This provision was found necessary to overcome the great atmospheric waves which on any day of hot sunshine were found to be continually rolling over tho mountain top to a height of over 100 ft. The most powerful instruments of research in the world are here located. First in importance is the instrument devised by Mr Hale and known as a spectroholiograph, or _ a spectroscope adapted to take sun pictures in light of certain orders. With this instrument pictures of the sun can be taken in tho light which comes to us through hydrogen gas, or again from glowing calcium and other elements. By this it may he understood that as these different elements have their positions mainly at different levels of the solar surface, so the astronomer using such an instrument may learn what is taking place in the sun’s outer layers and at different levels as well. From the report, recently to hana, of the year’s work we learn all about the latest discovery" made at that station, whereby it is found that the sun spots, of which eighty-seven groups were observed, change their polarities and intensities of magnetic fields from one spot period to another. In this way it .has been determined_ that if, in the present cycle, preceding spots in the Northern "Hemisphere of the sun have south-seeking conditions, while those in tlio Southern Hemisphere have the reverse, *we may be sure, oven predict with certainty, that the reverse will hold good for the next cycle of solar activity, just as surely as that the con-

dilions in this c.vclo ara opposite tn those which prevailed in the cycle before this present one. Just why the preceding spot of a group should at one time be positive and at another.^ negative, while the following spot is exactly the opposite at each period to this, is still very much of a problem. It is 0)10 that" will yet be found; to have an influence upon terrestrial magmatic conditions ruling upon our earth, and may lead to results of great importance. If, as has been suspected, those changes are intimately associated with the quality of radiation, as well as quantity, that tho_ elements malting up the outer covering of the sun, especially that of the photosphere, the intensely bright layer from which_ we receive the greater part of our light and- heating properties, and upon which all that lives upon the surface of this earth of ours is dependent, is intimately affected by the changes made manifest in the spots, then the importance of this discovery begins to be appreciated. Coupled with these precise measurements of magnetic phenomena are others for determining the ultraviolet radiation. These are measured by sensitive apparatus in which the galvanometer plays its part, and records are made,every minute during the day.