THE SQUTHERN HEAVENS

Evening Post, Volume CIX, Issue 33, 8 February 1930, Page 21

THE SQUTHERN HEAVENS

A FASCINATING STUDY

(Reviewed by " Omega Centauri.")

It is a splendid omen for the future of astronomy in the South, that tho Government Astronomer of New South Wales has thought fit.- to write a book on the southern stars, specially designed for the use of those who have'little-or no knowledge'of astronomy. This grand science, can^ never take, the. place that it should in national life until there is .an. interested, educated, and appreciative public. A book iikp this, if widely read, will do much to spread the requisite interest and to give to all who study it a glimpse of the vast field of research in which astronomers are making most astounding discoveries. The objects described in the .book arc chiefly such as can bo observed with the naked eye or with a pair of field glasses. .. .» r ' Six simple maps show the constellations which can be observed from the latitude of Sydney during the evening of any day throughout the year. These maps will serve fair,ly:well for any place in Australia or New;. Zealand. In-Wel-lington, for instance, only 7-J degrees of the northern sky.as shown are hidden, and we can sco instead the same amount to the south. In using any one of these maps it : should always be held so that the point of the horizon directly in' front of the* observer is at the bottom of the picture. The constellations from the horizon to the zenith can then be read off. But if the heavens are: to make any adequate impression on, the observer, the strars.'must not be thought of as me.ro points of ...light. Some idea of, their: immensity and their stupendous characteristics must; lie acquired. Mr. Nangle/ therefore, wisely ■ gives an introduction, which includes a clear picture of the^way in which the apparent motions of the heavenly bodies are due in great'part to the real movements of the; earth, spinning on 'its..axis vas. it rushes'along its. vast orbit Tound the, sun. . Another :-noint: 'discussed is. the preeisb'meafynng.ro| the term "magniJuSe" as applied to stains. One of the,;most .iinportanti'cnapters tells, how the spectroscope enables 'astronomers \to classifyrstars and to, determine the dotails of .the.-chemical and physical conditions of'i'thejr1 surf aces, ;in» particular their ; (temperatures, aiid'also their motions in'the ;li?ie of sight."" In glancing at the .fascinating' subject of stellar variation' it'is ~etated i that over 5000 variable; stars are, now known, whereas qnly"iJß.";hii^'i'-'been'%diScovered 80 years ago.' '^pe'cial'-'attention! 'is .given 'to eclipsing variables and to Gcpheids. As;ronomers are able to give astonishingly complete pictures of the dimensions and motions of the former systems, and use the latter as 'Standard candles in determining , tlie size of the universe. The-short chapter on double and multiple stars makes the reader realise that thousands of the minute points of 'light,''-which-., he. sees with. -, his field glasses, are in , reality pairs, or more complex systems, of gigantic suhs r The vast distances which separate star from star are indicated by the recent estimate that light, speeding' over 186,000; miles'a second; would take 300,000 years to cross' the great spiral, system of tho Milky Way; ;' '■ • -:'"■ •.;:<■. ■-'■■"■■ ''■':■ The avitlior thfen passes on to. the ' cons tell ations. and, a "description of th c groups and -'-.objects ,in.different months. On page 40 a misprint gives the position of -Phoenix as east instead of west of Eridanus, and on page 60 Ara and Triangulum are said to be due east instead-of-south. ■; Four of the beautiful photographic /reproductions are from negatives taken at Sydney by H. C. Russell,-,and-tho. .frontispiece, is from o'rio taken by W. F. Galo. The book is published at the price of ,5s by iCessrs'.j Angus and Eobcrts6i^; Ltd.. 'of Sydney.1 ' >:: ; ■„;;■■;;; -'^'■',■}..{■/'. -, ',■-