ASTRONOMICAL NOTES.

Press, Volume LIX, Issue 17700, 28 February 1923, Page 6

ASTRONOMICAL NOTES.

FOR MARCH

(BPECiALtT mrms ros "the pbsss.")

B? E. G. Hogg, M.A., F.R.A.S,

The sun enters the zodiacal sign Aries on March 22nd, at 2.59 a.m.; day and night will be of equal length over all the earth on this date. The sun's distance from the earth will then be about 92,514,000 miles. The planet Mercury rises on March Ist at 3.25 a.m., and on March loth at 4.12 a.m.; between these dates its brightness increases from 0.2 to —O.l, and it should therefore be a very conspicuous object in the eastern sky. Venus rises on March Ist at 1.55 a.m., and on March loth at 2.18 a.m. Mar's sets on these dates at 8.29 p.m. and 7.57 p.m. respectively. Jupiter rises on March Ist at 9.27 p.m., and on March 15th at 8.26 p.m. Saturn rises on these dates at 8.22 p.m. and 7.24 p.m. respectively.

There will be a partial eclipse of the moon on March 3rd which will be partially visible in New Zealand. The eclipse will begin at 4.43 p.m., and the middle of the eclipse occurs at 0.2 2).ni, The moon will not rise that evening until 6.35 p.m., so the most spectacular part of the eclipso will not be seen in Christchurch. The moon leaves the umbra at 8.6 p.m.. and the eclipse ends at 9.21 p.m. At the middle of the eclipse only about two-fifths of the lunar disc will be hidden.

The annular eclipso of the sun on March 17th will not be visible in New Zealand. The narrow belt over which the sun will be seen as a bright ring starts in Patagonia, crosses the South Atlantic Ocean, and ends in South Africa. No very great scientific importance attaches to an annular eclipse of the sun, though to the expert photographer it may provide tho means of obtaining very accurate records of the relative positions of the sun and moon during the progress of the eclipso. As a spectaclo it is striking, though it is not accompanied by tho apparition of the corona, which constitutes the chief glory of a total eclipse.

There will be an occupation of the planet Saturn by the moon on March 6th, the earth, moon, and planet being in a line ut 3.13 a.m. The phenomenon will just be visiblo as a very brief occultation in the latitude of Christchurch; further south it will be seen as a close graze. In a recent issue of "Popular Astronomy," Mr J. A. Worthington stresses the need that exists for the establishment of an observatory, on or near the Equator, to bo specially devoted to the study 'of the planets and cognate bodies. It appears that out of 153 observatories listed by the Nautical Almanac, there are only seven at a height of 4000 or more feet above sea-level, and of these, those only are in the tropics, and none of them is equipped for or engaged in extensive planetary work. The site he suggests is the neighbourhood of Quito, where, at the altitude of 9500 feet, the conditions of observation are almost ideally perfect. Here, he considers, might be carried out, among other branches of research, an exhaustive effort to determine whether the earth possesses, as is quite possible, any minute moteoric satellites which circle round it liko the moon, but much nearer than that body; When wo call to mind that Jupiter's fifth satellite is only 2.66 radii from his centre, that Phobos revolves round Mars at a distance of only 2.76 radii, or 5850 miles from it, and that the inner edge of Saturn's ring is only 1.37 radii from his ccntro, we see that there is no inherent improbability in the supposition that the earth may hnvo a sntellitp at, say, a distance of 2.66 radii from its centre. If such a companion existed, it would revolve round the earth in six hours; it could never rise above the horizon to observers in latitudes 69 degrees north or south, and would appear low in the Bky to most of the existing obaerva-j tories. If it were fainter than the south magnitude it could scarcely be detected by the naked eye, and if caught in a telescope would probably be taken for a meteor. Such a body might, however, be occasionally seen as it passed across the sun's disc, and the history of astronomy reveals many I eases where anomalous black spots—which apparently were not "sunspots"—have been detected on the sun by various, observers. We know that when one of Jupiter's satellites crosses his disc, it appears as a round black spot, and it is not unreasonable to suggest that the interposition of an opaque I body between the earth and the sun i may explain' the spots observed on the ! solnr di3c. The search for such meteoric satellites can be made with greater hope of success at an equatorial observatory than elsewhere, and so we trust that sight will not be lost of Mr Worthington's suggestion. We are indebted to Professor W. IT. Pickering for recently drawing our attention to a strange phenomenon observed on the evening of February 9th, 1913, when what can be best descibod as a slowly-moving procession of fireballs and meteors, all following apparently the same path, passed across the'.sky from horizon to horizon. It was first seen near Mortlach, 65 miles west of Regina. It traversed successively Manitoba, Minnesota, Michigan, Ontario, New York, Pennsylvania, and New Jersey. It then went out to sea, appeared next in Bermuda, was seen from the steamship Bellusia, and last from the steamer Newland in latitude 3deg 20niin south, longitude 32deg 30min west. The distance between the first and last stations at which this meteor flight was seen was no less than 5659 miles!

There appear to have been from 40 to CO fire-balls, arranged' at first in four or five separate group 3, talcing part in the procession. The interval during which the larger meteors were visible seems to have been from 30 to 40 seconds, and the whole display lasted about five minutes. Several of them had long tails, doubtless due to the fact that in their rush through our atmosphere innumerable fine particles had been swept off them. In Canada their colour was usually described as yellow or reddish, but not white. They were generally compared to bright stars, but in Bermuda the two leaders looked like large arc lights, slightly violet in colour, and of diameter equal to that of the moon, from which Professor Pickering inferß that if the meteors passed at a distance of about 70 miles from the observers in Bermuda, the diameters of the two leaders were about 28 inches. Prom a careful examination of the data, Professor Pickering concludes that the meteors crossed Ontario at a height of about 35 miles above the ground, and continued practically at this elevation until reaching the Bermudas, when they rose slightly. When seen from the Bellusia their height was, he thinks, about 45 miles, but this level was not maintained for long, and when sighted from the Newlands they had sunk to within 14 miles of sealovel. Finally they plunged into the Atlantic ocean a fow hundred miles beyond the spot at which they were laßt seen. The whole episode is quite unique in tho nnnnls of astronomy, and opens up a wido field for speculation, but it will bo well perhaps to postpono any imaginative flights until o, furthor papor dQOling with other

points of interest -which Professor Pickering is writing comes to hand. A valuable addition to our knowledge of the larger Magellanic Cloud has been made by the discovery that certain faint objects in it which have hitherto been supposed to be nebular are reality globular clusters. Prom careful measurements which have been made of five of these clusters, it is inferred that the "cloud" as at a distance from the earth represented by no less than 110,000 years, a conclusion well in accord with that obtained some years ago by Hertzsprung from entirely different considerations. If this estimate of its distance be correct, it follows that about 15,000 years would be required for a ray of light to traverse a diameter of the cloud. This strange object in our skies is thus invested with a further interest when we realise its huge dimensions and know that within it exist starsnebulae and clusters, such as characterise our own galactic system. From the issue of "Nature" for December 9th, we learn that notice of the discovery on December Ist by a Eoumanian astronomer of a nova, or new star, had been furnished to all the leading observatories of Europe and America. Exact details as to its position and magnitude having been supplied, a search was made for the star as soon as favourable weather conditions admitted, but though the moon was reported as of the first magnitude no trace of it could—according to the next issue of "Nature"—be found, and a telegram to Bucharest elicited the fact that the Astronomical Society of that city was in ignorance of the discovery. It is, of course, possible that the. observer was honestly mistaken as to tho nature of what ho had seen and reported, but it is also possible that a reprehensible hoax has been perpetrated at the expense of the astronomical fraternity. The history of astronomy shows that such mistakes have been made or hoaxes indulged in before, but those who are responsible for them probably have not been aware of the loss of time and the dislocation of the work of the observatory they may have caused. The number of hours during which a large telescope can be used is limited, and the programme of observation for each night is carefully worked out, so that the number of minutes the telescope is idle may be reduced to a minimum. The advent of a new star of the first magnitude is an event of such importance that doubtless the work of the whole observatory would-be suspended so that all the available equipment could be utilised to gather information regarding the stranger, with the result that when the search is based on misleading information many valuable hours, which might have been devoted to other objects, are lost.