STARS. 



Celeftial Bodies (p. 6i — 63. )> is of opinion, tliat fome 

 ftars, by their prodigious fwift rotation on their axes, may 

 not only aflume the figures of oblate fpheroids, but that by 

 the great centrifugal force ar'fing from Uich rotation'!, they 

 lij^y become of the figures of mill-ftoncs, or be reduced to 

 flat circular planes, f) tliin, as to be quite invifible when 

 their edges are turned towards us, a' Saturn's ring i; in fuch 

 pofition. But when very eccentric plamts or co nets go 

 round any flat ftar in orbits much inclined to its equator, the 

 attraftion of the planets or comets in their pcniiciions mult 

 alter the inclination of the axes of that itar; on which ac- 

 count it will appear more or lefs large and luminous, as its 

 broad fide is more or lefs turned towards us. And thus he 

 imagines we may account for the apparent changes of mag- 

 nitude and luftre of thole ftars, and likewife for their ap- 

 pea-ing and dilappeaiing. 



Hevelius (Cometograi)h. p. 380.) apprehends, that the 

 fun and ftars are furrounded with atmofpheres, and that, 

 whirling round their axes with great rapidity, they throw 

 off great quantities of matter into thofe atmofpheres, and 

 thereby caufe great changes in them ; and that thus it may 

 come to pafs, that a ftar, which when its atmofphere is clear, 

 fhines out with great luftre, may at an<ither time, when it is 

 full of clouds and thick vapours, appear grejtly dimiiiifhed in 

 brightnefs and magnitude, or even become quite invifible. 



The periodica! variation in the light of the ftars has alfo 

 been afcribed to the interpofition of the planets which cir- 

 culate around them ; but it is by no means probable, that 

 thefe planets, even if they do exill, are lufficiL-ntlv large to 

 obftrudt anv large portion of their light. Even when feen 

 from the earth, the light of our own fun is not fenfibly im- 

 paired, when Mercury and Venus are pafting over his difc. 



The ingenious Mr. Pigott has ventured a ftep farther 

 than any of his prcdtceilors in this branch of attronomy. 

 In his inveftigation of the phenomena exhibited by the va- 

 riable ftar of Subieflii's ftiield, the periodical changes of 

 which are affefted by very fingular anomalies, he fuppofes, 

 that the greater part of its dilc is unenlightened ; and that 

 a few luminous fpot", placed at certain intervals, produce, 

 by the rotation of the ftar, all, the variations which have 

 been obferved. Mr. Pigott fuppofes, that the body of the 

 ftars is dark and folid ; that iheir rotation on their axes is 

 regular; and that the furroui;ding medium is occafionally 

 generating and abforbing its luminous particles, by a pro- 

 cefs fimilar to what Dr. Hcrfchel fuppofes is going on in 

 the atmofphere of the lun. He imagines, that thefe lu- 

 minous panicles are fparingly dilperfed in the atmofphere 

 of the variable ftar of Sobielki, from the circumftance of its 

 diminiftiing even to the ninth magnitude ; and as the dura- 

 tion of its full luftre continues only about 9^ days, while it 

 performs a complete rotation in 62 days, he confiders the 

 luminous fpots to be f imewhat circular, and of no great 

 extent. Since this fmall portion of light may naturally be 

 fuppofed to diminifti and finally difappear, Mr. Pigott 

 imagines, that this may have been the caufe of the difap- 

 pearance of the new ftars of 1572 and 1604. Hence he 

 concludes, that there are others which have never fliewn a 

 glimpfe of brightnefs ; and that there are " primary in- 

 vifible bodies, or unenlightened (lars, that have ever remained 

 in eternal darknefs." Following out this notion, Mr. Pi- 

 ott conceives, that clulters of thefe dark bodies may be 

 ound, .".nd by intercepting " all more diltant rays," may 

 appear like dark fpaccs in the heavens, fimilar to what has 

 been obferved in the foufhern hemifpherc. 



Star.s, As for the Nature of the fixed, their immenfe 

 diftance leaves u^ greatly at a lofs about it. What we can 

 gather for certain from their phenomena is as follows : 



1 . That the fixed ftars are greater than our earth : be- 

 9 



I 



caufe, if that was not the cafe, they could not be vifible at 

 fuch an immenfe diftance. 



2. The fixed ftars are farther diftant from the earth than 

 the farthe!t of the planets. For we frequently find the 

 fixed ftars hid behind the moft diftant of the planets: and 

 befides, they are fuppofed to have no parallax, which the 

 planets have. 



3. The fixed ftars ftiine with their own liirht ; for they 

 are much farther from the fun than the rcmoteft planet, and 

 appear much fmaller ; but fince, notwithftaiiding this, they 

 are found to fhine much brighter than fuch planet, it is evi- 

 dent they cannot borrow their light from the fame fource aa 

 that does, viz. the fun ; but fince we know of no other 

 luminous body befide the fun, whence they might derive their 

 light, it follows, that they ftiine with their own native light. 



Belides, it is known, that the more a telefcope mag- 

 nifies, ti.e lefs is the aperture through which the ftar is feen ; 

 and, confequently, the fewer rays it admits into the eye. 

 Now fince the ftars appear lefs in a telefcope which mag- 

 nifies two hundred times, than they do to the naked eye, 

 infomuch that they feem to be only mdivifible points, it 

 proves at once that the ftars are at immenfe dillances from 

 us, and that they fhine by their own proper light. If they 

 fhone by borrowed lifjht, they would be as invifible without 

 telefcopes as the fatellites of Jupiter are ; for thefe fatellites 

 appear bigger, when viewed with a good telefcope, than 

 the larijeft fixed ftars do. Hence, 



1. We deduce, that the fixed ftars are fo many funs ; for 

 they have all the charafters of funs. 



2. That, in all probability, the ftars are not fmaller than 

 our fun. 



3. That it is highly probable, that each ftar is the centre 

 of a fyllem, and has planets or earths revolving round it, in 

 the lame manner as round our fun, ;'. e. it has opaque bodies 

 illuminated, warmed, and cherifhed by its light. As we 

 have incomparably more light from the moon than from all 

 the ftars together, it is abfnrd to imagine that the ftars were 

 made for no other purpofe than to caft a faint light upon the 

 earth ; efpecially fince many more require the affiftance of a 

 good teleicope to find them out than are vifible without 

 that inUrument. Our fun is furrounded by a fyftem of 

 planets and comets, all which would be invifible from the 

 neareft fixed ftar ; and from what we already know of the 

 immenfe diftance of the ftars, it is eafy to prove, that the 

 fun, feen from fuch a dillaiice, would appear no bigger than 

 a ftar of the firft magn-itude. 



From all this it is highly probable, that each ftar is a fun 

 to a lyftem of worlds moving round it, though unfeen by 

 us ; efpecially as the doArine of a plurality of worlds is 

 rational, and greatly manifefts the power, wifdom, and good- 

 iiefs of the great Creator. 



How immenfe, then, does the univerfe appear ! Indeed, 

 it muft either be infinite, or infinitely near it. 



Kepler, it is true, denies that each ftar can have its 

 fyftem of planets as our's has ; and takes them all to be fixed 

 in the fame furface or fphere ; urging, that were one twice 

 or thrice as remote as another, it would appear twice or 

 thrice as fmall, Inppofing their real magnitudes equal; 

 whereas there is no difterence in their apparent magnitudes, 

 jullly obferved, at all. But to this we oppofe, that Huy- 

 gens has nut only ftiewn that fires and flames are vifible at 

 diftances where other bodies, comprehended under equal 

 angles, difappear; but it (hould likewile feem, that the 

 optic theorem about the apparent diameters of objeii^s, 

 being reciprocally proportioiul to their diftances from the 

 eye, does only hold while the diameter of the object hsa 

 fome (enfible ratio to its dillaiiee. 



As for periodical ftars, &c, fee Chan^et, &c. of&TAV.s,fupra, 



Stars, 



