THE TRANSIT OF VENUS.

Feilding Star, Volume III, Issue 50, 9 December 1882, Page 2

THE TRANSIT OF VENUS.

j This furiously expected phenomenon j sp in. port nt to a-tivii ->mers, and for_the ' nbc-Tvance of which such great prepara- : iic)i)s have been made in various parts of I he world, has passed off with treat suc-cest-in this colony, and at .Melbourne, as j will be seen by our teicg 'aphie despatches p ibiished elsewhere, and if the observers in the .Northern Hemisphere have been as fortunate, that big'. ly important prob" lem, n imely the true distance of the "strw irom our planet (at present estimated afc about 91 millions of miles), upon-which.-depends all other astronomical measurements beyond our moon, will have been satisfactorily solved as soon as the requi- ' site cdeubitions hare been made. Tl'e transit as observed in Feilding through the telescope was au exceedingly interesting spectacle. The sun rosejn-fe very clear sky with the planet Venus of the a parent size and shape of a cricket ball floating across his disc. 'Shortly afterwards, however, he was obscured for ab 'lit three-quarters of an hour, but the remainder of the transit was well seea with the exception' of a few light cirrus clouds which occasionally intervened} .and (as occurred at New Plymouth) the external contact at egress was not so well defined as it might have been owing to the in erfeiv nee ot a vexatious cloud just before it took place. Tiie internal contact of the planet with the outer limb.of fche suu was, however, well defined. *■ * The following short explanation of the modus operandi in determining the sun's distance hy means of a transit of Venus may be im resting to those of our r eders who are not acquainted with the subject. — A transit can, of course, only .tytke place when the planet is exactly betw^gi the earth and stm, which is of very rare occurrence, (two transits of S j'ears between them Uiking place about every 105 years.) The planet when thus situated, as seen by two observers placed at different stations upon the earth, the furfch r apart the better, appears to enter upon the sun's face at different points and cross its disc in parallel lines. JN'ow, the object to be attained is the distance between those lines, a problem which depends upon the accuracy with which each, ibserver is enabled to note the time wnen the planet enters upon and leaves the s m at each station. That distance being etermined, the distance from the earth to the sun is readily calculated by trigonometry on the we! -known mathematical ixiom that when two angles and Qne._si.d_ft of a triangle are known, the other two sides and angle can be easily ascertained.