OF CURENT INTEREST

Taranaki Daily News, 13 October 1934, Page 13 (Supplement)

OF CURENT INTEREST

SOME NEW TELESCOPES

(By the

Rev. B. Dudley,

F.R.A.S.)

Canada, which has already achieved great things in the way of building larger telescopes, is shortly to make another addition to its credit. This is the 74-inch aperture about to be donated to the Toronto University by the widow and son of the late David Dunlop. It is one of their excellent ways of honouring his memory. The instrument will be of British construction, the firm of Sir Howard Grubb, Parsons and Co., Newcastle on Tyne, carrying out the contract, while another English firm is to build the observatory to house the telescope. All that is now required to complete the project is the Speculum, which is well on the way to completion. This mirror, Mr. Allan Bryce informs us, is 12 inches thick, of special pyrex glass, and the disc was produced at the Corning glass works, where also the disc for the projected 200inch telescope was cast. The Greenwich Observatory is also to be fitted with new equipment in the shape of a reflecting telescope of 36 inches aperture. This acquisition, together with the housing accommodation, is due to the generosity of William Johnston Yapp, being intended to mark his appreciation of Sir Frank Dyson’s good work as Astronomer Royal. The disc is 6 inches thick and weighs 5501b5. The dome, 34 feet in diameter, is of steel and papier mache, the whole capable of being operated by the observer at the eyepiece.

Sparcity of Comets. So far this present year has not been marked by the apparition of a new comet. During most years one or more of these bodies make their appearance for the first time, more particularly the fainter varieties; comets, that is to say, which require the aid of a telescope to see them. The periodic ''comet Encke, however, has been picked up by observers at the Lick observatory, California. This was on July 16-11. Only for a few weeks could it be followed, as early in September it became lost in the glare of the sun. Southern observers will see it during the latter part of the year, though by that time it will have become a rather faint object.

This comet was designated after the astronomer of that name. He was at one time director of the Berlin Observatory. It was first seen by Miss Caroline Herschel in 1786, but Encke calculated its orbit and period of revolution about the sun—three years, 112 days. It has the distinction of approaching the sun on its regular visits more closely than the planet Mercury, and its orbit is smaller than that of any known comet. It completes its revolution 2j hours earlier at each return. Formerly this contraction of orbit was thought to be due to a slight resisting medium In space within the orbit of Mercury, but more recently other causes are suspected. 5 . ; •

Comet or Minor Planet? There are some reasons for thinking that the comet of November,, 1927, which was* discovered by Professor Schwassmann and Dr. Wachmann by photograpic means, may be after all an asteroid. Its behaviour seems to suggest that probability. It has a period of revolution about the sun of approximately Iffi years. Peculiar to it are several facts. Its nearest distance to the sun. is further from that luminary than any comet known. The departure of its orbit from the circular form is less than that of any comet yet observed. It is subject, to most remarkable fluctuations of light, varying from magnitude 12 to magnitude 17 in a very peculiar and irregular manner. In July last it passed its aptelion, or point of maximum distance from the sun. At the present moment it is making for its minimum distance, or perihelion. Every years since its discovery it has been visible, and it is thought that astronomers may be able to follow it visually, without a break during the whole period of its journeys about the sun. No known comet has ever been thus kept under observation. Astrononers are hoping that by the time it has completed its path they will be able to furnish some reasonable explanation of its movements, several of which could be accounted for on the supposition of its being an asteroid.

Lapse of the Sun. The sun, which in accordance with expectations had become active during the early part of this ear, having recently passed its quiescent stages, has apparently lapsed into a state of inactivity, there having been but few sunspots to indicate disturbance. Those that have been lately visible were. small and of short duration. During April and May there were several large spots, or spot groups, most of these were persistant and were carried round the sun with its rotation, thus reappearing on the side of the solar orb turned toward us. There have also been several single spots. Some observers report a large prominence during August. Those interested in sunspots are or need to be on the watch as these phenomena are quite sure to increase in the near future.

The 24-hours System. Various objections have been raised jo the adoption of the 24-hour system of time registration. In England, while the press has frequently been against it, the British Broadcasting Company has favoured its general use. W. Alfred Parr, president of the British Astronomical Association, points out that the adoption of the system could be new only in a few countries, since in several it has obtained general vogue, proving to be an unqualified success by reason of its entire removal of any possible ambiguity in the quotation of a.m. or p.m. time data. “Some dissentient writers,” he states “consider that the system will be found cumbersome in social intercourse, but I can personally assure them from many years’ residence abroad that they need have no fear on this head since it is quite permissible for the old system to run parallel with the 24-hour scheme. Thus in' Italy all official announcements are given in accordance with a 24-hour day (as even now in England for the Army, Navy and Air Force”). The entire question of subdividing the day is dealt with in an excellent presentation of the subject in the Nautical Almanac for 1933. Some have thought that possibly the adoption of this system would tend to perpetuate the duo-decimal division Of the day, and thus postpone the adoption of what they consider to be a still better subdivision —the decimal system.