THE INCALCULABLE MOON.

Star (Christchurch), Issue 11504, 28 September 1915, Page 4

THE INCALCULABLE MOON.

Greenwich ivha aoundc-tt by Charles IT,, the Westminster Onaette " says, nuiinly to;* tin- purple of investigating the move-mOnt* of the l moon fn the inioresU of navigation; but though generations of astronomers Jiavo in the intervening two and a. half centuries been working nL t!u> problem, the moon -has not yet. be. :i ithhU s amenable to t'lcir uis\Umnr;i.tirv. The astronomer-royn 1, in his report of the work at Greenwich dunn;;; the ]>ast) voir, call* attention t.> the increasingly hip deviation between tho calculated position of the moon in the. sky and its real pesifekm as xliown by the Greenwich observations. Tin < deviation has lately been increasing in a serious manner, the error year being more than tv.v!v« times as larger oh it wn.s twenty yen i's n v-»>- the average annual increase amounting during the two decades to half a second_ot nro in longitude. The cuusw ot 1 lie failure of astronomers to make the moon .ameiutblo' to their exact mathematics, based on the dynamical law of gravitation, is believed to be somo attractive force, of which we tire at present ignorant, though in all probahiiity one factor is the, true *b»pe or the eartli, which still :< accurate determination. .Fortunately. th r< chronometer and: wireless telegraphy haw 'Wide seamen practicably independent of lurior observations in ascertaining their position in. the- ocean:-. ■