POPULAR ASTRONOMY

Otago Witness, Issue 2812, 5 February 1908, Page 88

POPULAR ASTRONOMY

NOTES FOR FEBRUARY.

By Rev. D. Dctton, F.R.A.S., F.G.S. . The Sun enters the sign of Pisces (the Fishes) on the 20tb and will be in the constellation of the same name from the middle of March to the middle of April. The Moon will be new on the 2nd, first quarter on the 9th, full on the 17th, last quarter on the 25th. The Planets. — Mercury is an evening ?rar. Venue is an evening star visible in the «outh-west after sunset. Mars comes to tbe meridan before 4 o'clock in the afternoon, and is, therefore, well advanced towards the western horizon at sunset. Jupiter is an evening star, and may bo seen in the north-east early in the evening. It is sosjn-ilhant that it can scarcely be , mistaken for anything else than the giant < planet. Saturn is an evening star, but is i too near the western horizon at nightfall 1 to be of much interest to the naked eye observers at present. The Constellations.— The Southern Cross is at,a higher altitude in the south-east than it was last month, and Alpha and Beta i Centauri, the pointers which always keep the same relative position to the Cross, aic also higher than they have been for some time past. Argo, the ship, with its leading star, Canopus, is well up towards the zenith. Argo is a very large constellation, and contains some hundreds of naked-ey* starsIn this group there is a very remarkable variable star "Eta Argus. Its mean magnitude appears to be between* the 6th and 7th. In 1837 it had so increased in 'brightness that Herschel, observing it from the Cape of Good Hope, said that, " Sirius and Canopus excepted, it^could only be compared with Rigel. which it .somewhat surpassed." Its maximum of brightness wai reached in the early part of January, 1838. It then began to wane, but flaied up again in 1843, when Maclear observed it to be brighter than Canopus. and, though it soon slightly faded, it remained one of the most brilliant stars in the southern sky until 1850, when it steadily declined till 1887, and was then rated as a star of the 7th magnitude, that is, below visibility to the naked I eye. Its brightness has increased slightly i during th* past few years, and may be I slowly rising to another maximum. Surrounding ihis variable star is a magnificent nebula rfombhiiff the great wbula in Orion. fiir John Her.«ehel says, "It 1.5 not easy for {mguage to convey a full impiov i sion of ? ':<z beaut \ and sublimity oi f Le

spectacle which ihe nebula offers as it enters the field of view of the telescope ; it forms a sort of climax in a part of the heavens otherwise full of interest." It" may be said that probably no pai-t of the sky is richer in 3tellar wonders than the regions covered by our circumpolar stars.

Taurus (tbe Bull) is between north and north-west, with the Pleiades lower and further to the north-west, Aldebaran, the fiery eye of the bull, is placed in the cluster called flic Hyades, and is conspicuous among the neighbouring stars by its brightness. It is of the first magnitude, and ranks among the 20 brightest stars. It is much larger than the Sun, and at the Sun's distance from the Earth would give upwards of 4-0 times more light than the Sun gives. We are thankful that a star of such dimensions is so far away as to be non-effective in increasing the Earth's temperature. There is no probability^of it getting any nearer, as it is said to be receding from us at the rate of about 30 miles a second. At present its light reaches us approximately in about 32 years. Dr Johnson defines the word "Hvades." as "a watery constellation," Spencer calls them the " moist daughters," and Tenn>eon, in bis "Ulysses, says: "Through scudding drifts the rainy Hyades vexed the dim sea." This has been the character attributed to the Hyades fiom the earliest times. The Roman country people called them the " Little pigs."' Pliny accounted for this familiar title by the fact that the continual rains of the season of their setting made the roads so miry that these stars seemed to delight in dirt-like swine. Canib major, with Sirius, is nearing the zenith ; lower, and between north-east and north, is Canis minor, with Procyon. A little to the north-west Orion is making a splendid figure. Towards the western horizon Cctus (the Sea Monster) may still be seen early in the evening. Aries (the Ram) is near the north-western horizon, below and further west than the Pleiades. Gemini, with Castor and Pollux, is between north-cast and north. The inconspicuous zodiacal constellation Cancer (the Crab) may easily be found from its being in tho r-osition occupied at present by Jupiter. Leo (the Lion) is coining into view above the north-eastern horizon. There should be no difficulty in recognising this constellation. A number of its stars are grouped in the form of a sickle, having Regulus, its principal star, in the handle of the sickle. Regulus is easily picked out by its superior lustre among the stars in which it is placed. Another interesting 1 star in Leo is Denebola, which is at some distance east, of Regulus, and which is said to form tho tuft of the Lion's tail. The sickle is supposed to represent the head and forepaws. Alphard ("the Solitary One"), the chief star in Hydra .has moved higher above the eastern horizon, and is better placed for observation. Between east and south-cast there are four stars forming a sort of irregular square. This is Corvus (the Crow). The sailor knows it by a name that is certainly more descriptive — "the Cutter's Mainsail."

In locating the stars it should be remembered that, the farther south the observer is placed the higher the southern stare will appear above the horizon, -and the northern stars will be lower. This, of course, is reversed as the observer goes vorthward.

ITEMS OF INTEREST.

A great name will henceforth be missed from ±\i& ranks of native workers in astronomy, though her work will remain a rich legacy of astronomical information, and her example of devotion to a chosen pursuit will abide as a perpetual incentive to other students in the came line of research. Miss Agnes M. Clarke, who passed away last year, was the most outstanding of women students and writers on astronomy. By her many published articles and books she attained a position of authority in the ranks of modern astronomers. _ Among her books may be mentioned "History of Astronomy during the Nineteenth Century " (a vvoik which met with the universal approval of astronomers). " The Hcrs«hels in Modern Astronomy," "The System of^ the Stars" (an exhaustive and up-to-date survey of the investigations, discoveries, and unsolved problems in tho realms of sidereal astronomy), " Problems in Astrophysics " (a survey of solar and stellar spectroscopy), and " Modern Cosmogonies," which was her last work, published 1906. So greatly was her work appreciated that she was elected an honorary member of the Royal Astronomical Society, an honour conferred upon only three "iother women — Caroline Herschel, Mary Surnmervillc, and Lady Huggins. Miss Clarke was far from being "an undevout astronomer." a being that the poet Young said "is mad." Her writings, all in the first rank in the litciature of astronomy, are pervaded with a sweet and captivating reverence for the Great and Beneficent Being " who made the stars al K o." The number of women interested in astronomy i-5 increasing, especially in America, and some are doing first-class work as practical astronomers. As yet, we do not know that tlie subject has taken on with any of our girl graduates. Probably this is due to the want of facilities in our seats of learning.

Mr Hector M'Phereon has communicated to an American journal a. very interesting article on " The Observatories of Scotland." While, admitting that the climate of Scotland is far from beinp; ideal for astronomical observation, he shows, as is generally acknowledged, that Scotland has reason to bo proud of her contributions to the progress of the great science. The office of Astronomer-royal of Scotland was creafjrd in 1834-, and the first appointment to the office was an excellent one in every way. The famous Thomas Henderson had thp honour of being the Astronomer-royal first in a succession of able men. There are two observatories in. Edinburgh, said to be among the best institutions of the kind in the three kingdoms — the Royal Observatory on Blackford Hill and the City Observatory on Calton Hill. The former, taking the place of the old Royal Observatory, was erected in 1888, and was largclv equipped by the Earl of Crawford from his private observatory in Aberdecnsliire. In 1889 the old Royal Observatory buildings were taken over by the City Council of Edinburgh, and became the City Observatory. A director was appointed, with the title of Astronomer to tho city of Edinburgh. The council was fortunate in securing as its first director a very accomplished practical astronomer in Mr W. Peck, F.R.A.S. This institution is popular, and is taken advanrage of freely by the citizens. It ha 3 tho laraest refracting telescope in Scotland — 22in — and a large reflecting telescope, and other smaller but powerful instrument*. The Glasgow University Observatory is the oldest in Scotland. In 1760 a sum of money for the erection of an pbsenatoiy was

bequeafec! by Dr M-acFarlane, a tsontleman resident in Jamaica. The observatory is well equipped with a first -class refractor of 9in and a reflector of 20in. Tho Royal and the Glasgow institutions have been presided over by a. succession of eminent directors, and among their assistants have been several who have made names for themselves in astronomical research. There are no observatories in connection with tho Universities of Aberdeen and St. Andrews or the College of Dundee. Mr M'Pheraon says this is to be regretted, as the climate of Aberdeen especially is excellent for observation. We may add that it is also to be regretted that there is no observatory in connection with the university of the Edinburgh of the South, where splendid results might be achieved in exploring those interesting regions referred to in a previous paragraph. We fervently hop© this want will be supplied in the near future by the public or private munificence of the oitizons. To the question, "What is the use?' we may give Professor Todd's reply — " Only a very small and unaspiring mind ever asks this question about any science which -*Ms to the gum total of our actual knowledge, least of all with reference to this — one of tbe most practical of the sciences. Astronomy binds earth and heaven in so close a bond that it even maps the one by means of the other, and guides fleet and caravan over wastes of sea and land otherwise trackless and impassable, and it is hardly an exaggeration to say that there is no civilized person whose comfort is not enhanced, whose life is not more worth living, or who is not affected at least indirectly by the work of astronomers, and by those who, though not astronomers, are yet practically applying the principles of the science to the affairs of everyday life."

Many people arc not aware of the important part played by dust in the atmospheric aspects of the sky. The fact, however, was deeply impressed upon the general intelligence by the results of the great v olcanic outburst at Krakatoa, near Java, in 1883. Vast quantites of voloanio dust were shot up into the higher reaches of the atmosphere and carried by air-currente all round the world, producing for many months the most wonderful and gorgeous sunrises and sunsets on record. Smokeclouds from extensive bush and grass fires may occasionally be the cause of highlycoloured sun and moon, but the principal cause is the dust particles with which the atmosphere is always more or less loaded. When the sun is rising or setting, its rays reach us in a slanting direction, and, therefore, have to pass through greater and heavier layers of dust and vapour laden atmosphere which obstructs the more delicate rays of sunlight, while the coarser red and yellow rays have, by their greater penetrative momentum, power to force their way through and make themselves visible in the glorious colouring often seen in the eastern and western skies at sunrise or sunset. There is a very interesting chapter on the "Importance of Dust" in Alfied Russel Wallace's book, " The AVonderful Century."'