Current Astronomical Errors.

Oamaru Mail, Volume XXXV, Issue 10014, 3 December 1908, Page 1

Current Astronomical Errors.

Some popular and familiar notions in trouomv are stated by Professor .T. K. ore to be fallacious. In an article conibuted to Knowledge and Scientific ews /London, September) he says, her things:— "It has heen stated that the moon as en with the highest powers of the ijrcnt erkes telescope appears 4 just as it avoulc! 4 seen "with the naked eye if it were susmded sixt-v miles over our heads.' Hut is statement is quite inaccurate. The oon as seen with the naked eye. or in a lesrope. shows us nearly a whole hemi- . there of its surface. But were the eye aced only siylv miles fvoni its surface c should see only a small portion of its - iaible hemisphere. In fact, it is a curi- • is paradox that the nearer the eye is • a t.b" less we s-ee of its surface! ' "he truth of this "will "he evident from the ' -,ct that on a level plane an eye placed a height of, say. five heot, sees a very nail no'tion nf Hie earth's surface in- (" ?ed, and the higher we ascend the more ' ? the surface we sre. 7 find that at a : i : stance of sixty miles from the moon's f ivface we should only see a small frac-' ton of its visible hemisphere (about ] 90th). The lunar features would also ci ipear under a different asp-ect. The view would be more of a landscape than that seen in any telescope. This view of the matter is not new. It lias beeiT previously pointed out, especially by M. Fhinimarion and Mr Whitmell, but its +vuth is not. I think, generally recognised. Professor Xewcomb doubtr, whether with any telescope the moon has ever been seen so well as it would be if brought within five hundred miles of the earth." -Anether common idea—that stars may be seen in the daytime from the bottom or a deep pit or high chimney—is stated by the writer to be quite incorrect: it has, he says, been often disproved, lie goes on : *

"Stars rmiv, however, be scon in the daytime with even small telescopes. Tt is said that a telescope of one-inch aperture will show stare of the second mnprniturle, like those in the 'helt-' of Orion or the brighter stars of the 'Plow'; of two inches, stars of the third magnitude: and of four inches, those of the fourth magnitude. V»nt X can not confirm tins from personal observation. Tt may lie so, but not tried the experiment." Current laudation of photographic me--Ihods in astronomy is not regarded by Professor Gore as altogether warranted. He says:— ''The photographic metliod of charting the stars, although a great improvement 011 the old system, seems to have its disadvantages. One of these is that the star images are liable to disappear from the plates in the course of time. The reduction of stellar photograph plates should therefore be carried out as soon as possible after they are taken. Dr "Roberts found that on a plate originally contain insr 364 stars, no less than 130 had completely disappeared in nine and onefourth years. "It has been assumed by some wfit ens on astronomy that the faint stars visible on nhotogranhs of the Pleiades are at practically the same distance from the earth as the brighter stars of the cluster, and that- consequently there must be an enormous difference in a ctual size between the brighter and fainter stars. P»ut there is Teallv no warrant for any such assumption. -Photographs of the vicinity show that the skv all round the Pleiades is equally rich in faint stars. Tt- seems, therefore, more reasonable to suppose tint most of the faint stars visible in the Pleiades are reallv behind the olust»'r in space. For if all the faint stars visible on photographs belonged to the cluster, then if we imagine the cluster removed, a 'hole' would lie left in the skv, whi<h is, of course, utterly improbable. An examination of the proper motions tends to confirm this view of the matter, and indicates that the Pleiades cluster is a comparatively small one and projected on a background of fainter stark."