[[125]]
Suppoſe then, agreeable to what has been ſaid, the Globe of Saturn, Fig. 4. whoſe Poles are A, B. G N is the Diameter of the Ring, as you view it ſideways, repreſenting a narrow Oval. Thoſe that live about the Poles within the Arches C A D, E B F, each of which are 54 Degrees, (if the Cold will ſuffer any Body to live there) never have a Sight of the Ring. The Appearances of the Ring in Saturn. From all other parts it is continually to be ſeen for fourteen Years and nine Months, which is juſt half their Year. The other Half it is hid from their View. Thoſe then that dwell between the Polar Circle C D, and the Equator T V, all that time that the Sun enlightens the Part oppoſite to them, have every Night the Sight of a Piece of it H G L, much in the Shape of a ſhining Bow, which comes from the Horizon, but is darken’d in the Middle by the Shadow of Saturn G H, which reaches moſt commonly to the outermoſt Rim of it. But after Midnight that Shadow by little and little begins to move towards the right Hand to thoſe in the Northern, but the Left [[126]]to thoſe in the Southern Hemiſphere. In the Morning it diſappears, leaving behind it a Likeneſs indeed of a Bow, but much paler and weaker than our Moon is in the Day time. For they, as I ſaid before, have an Atmoſphere, or an Air ſurrounding them enlightened by the Sun. Otherwiſe Night and Day they would have their Ring, their Moons, and all the fix’d Stars, equally conſpicuous. Another thing that muſt make the Sight of their Ring very curious, is, that by ſome Spots in it, it is diſcover’d to turn round upon it ſelf: A thing that thoſe that are ſo near cannot but take notice of, when we that live at this Diſtance can deſcry a great Inequality, the inſide of it being brighter much than the outſide is. When the Shadow of the Globe falls upon that part of the Ring G H, the Shadow of the Ring at the ſame time darkens another Part of the Globe about P F, which otherwiſe would have the Sun upon it. So that there is always a Zone of the Globe P Y F E, ſometimes of a larger extent than at others, which is depriv’d of the Sight [[127]]both of the Sun and Ring for a conſiderable time, the latter of which hides ſome part of the Stars from it too. And certainly an amazing Thing it muſt be, all of a ſudden to have the Sun intercepted and to become as dark as Midnight, without ſeeing any Cauſe of ſuch an Accident. All which time their Moons are their only Comfort. The other half of the Year the Hemiſphere T B V enjoys the ſame Light that T A U before did, and then this undergoes thoſe long Eclipſes that That before ſuffer’d. At the Equinoxes, when the Sun is in the ſame Plane with the Ring, the Inhabitants of Saturn cannot well perceive it: no not even we with our Glaſſes, by reaſon of its Darkneſs. This happens when Saturn, view’d from the Sun, is advanced one and twenty degrees and a half in Virgo or Piſces, as I have ſhow’d formerly in my Syſtem of Saturn: Where there is an Account given of the Riſings of the Sun above the Ring, throughout all the Saturnian Year. [[128]]
With Saturn in this Scheme you have the Globes of the Earth and Moon drawn in their true proportion, to put you in mind again of a Thing worth remembring, viz. how very ſmall our Habitation is when compar’d with that Globe or the Ring about it. And now any one, I ſuppoſe, can frame to himſelf a Picture of the Night in Saturn, with two Arches of the Ring, and five Moons ſhining about, and adorning him. This then is what I had to ſay to the primary Planets.
We are now come a little lower, to make an enquiry into the Attendants of theſe Planets, eſpecially our own. And here we ſhall not only conſider their Aſtronomy, but ſhall alſo ſearch into their Furniture and Ornament, if they are found to have any ſuch thing, which we have deferred conſidering till now.
Very little to be ſaid of the Moon. And here one would think that when the Moon is ſo near us, and by the Means of a Teleſcope may be ſo nicely and exactly obſerv’d, it ſhould afford us Matter for more probable [[129]]Conjectures than any of the other remote Planets. But it is quite otherwiſe, and I can ſcarce find any thing to ſay of it, becauſe I have not a Planet of the ſame Nature before my Eyes, as in all the primary ones I have. For they are of the ſame kind with our Earth; and ſeeing all the Actions, and every thing that is here, we may make a reaſonable Conjecture at what we cannot ſee in thoſe Worlds.
The Guards of Jupiter and Saturn of the ſame nature with our Moon. But this we may venture to ſay, without fear, that all the Attendants of Jupiter and Saturn are of the ſame Nature with our Moon, as going round them, and being carried with them round the Sun juſt as the Moon is with the Earth. Their Likeneſs reaches to other Things too, as you’ll ſee by and by. Therefore whatſoever we can with reaſon affirm or conjecture of our Moon (and we may ſay a little of it) muſt be ſuppos’d with very little Alteration to belong to the Satellites of Jupiter and Saturn, as having no reaſon to be at all inferior to that.
The Moon hath Mountains. The Surface of the Moon then is found, by the leaſt Teleſcopes of about [[130]]three or four Foot, to be diverſified with long Tracts of Mountains, and again with broad Valleys. For in thoſe Parts oppoſite to the Sun you may ſee the Shadows of the Mountains, and often diſcover the little round Valleys between them, with a Hillock or two perhaps riſing out of them. Kepler from the exact roundneſs of them would prove that they are ſome vaſt work of the rational Inhabitants. But I can’t be of his mind, both for their incredible Largeneſs, and that they might eaſily be occaſioned by natural Cauſes. Nor can I find any thing like Sea there, tho’ he and many others are of the contrary Opinion I know. For thoſe vaſt Countries which appear darker than the other, commonly taken for and called by the Names of Seas, are diſcover’d with a good long Teleſcope, to be full of little round Cavities; whoſe Shadow falling within themſelves, makes them appear of that Colour: and thoſe large Champains there in the Moon you will find not to be always even and ſmooth, if you look carefully [[131]]upon them: neither of which two But no Sea. Things can agree to the Sea. Therefore thoſe Plains in her that ſeem brighter than the other Parts, muſt conſiſt, I ſuppoſe, of a whiter ſort of Matter than they. Nor do I believe Nor Rivers. that there are any Rivers, for if there were, they could never eſcape our Sight, eſpecially if they run between the Hills as ours do. Nor have they Nor Clouds. any Clouds to furniſh the Rivers with Water: For if they had, we ſhould ſometimes ſee one part of the Moon darkened by them, and ſometimes another, whereas we have always the ſame Proſpect of her.
Nor Air, and Water. ’Tis certain moreover, that the Moon has no Air or Atmoſphere ſurrounding it as we have. For then we could never ſee the very outermoſt Rim of the Moon ſo exactly as we do, when any Star goes under it, but its Light would terminate in a gradual faint Shade, and there would be a ſort of a Down as it were about it; not to mention that the Vapours of our Atmoſphere conſiſt of Water, and conſequently that where there are no Seas [[132]]or Rivers, there can be no Atmoſphere. This is that notable difference between the Moon and us that hinders all probable Conjectures about it. If we could but once be ſure that there were Seas and Rivers in it, it would be no weak Argument to prove that it has alſo all other Furniture which belongs to our Earth, and the Opinion of Xenophanes might be true, that it has its Inhabitants, Cities, and Mountains. But as ’tis, I cannot imagine how any Plants or Animals, whole whole nouriſhment comes from liquid Bodies, can thrive in a dry, waterleſs, parch’d Soil.
The Conjecture of its Plants and Animals very dubious. What then, is it credible that this great Ball was made for nothing but to give us a little Light in the Night-time, or to raiſe our Tides in the Sea? May there not be ſome People there that may have the Pleaſure of ſeeing our Earth turn upon itſelf, preſenting them ſometimes with a Proſpect of Europe and Africa, and then of Aſia and America; ſometimes half of it bright, and ſometimes full? And muſt all thoſe Moons round Jupiter and Saturn [[133]]be condemned to the ſame Uſeleſneſs? I do not know what to ſay concerning it, becauſe I know of nothing like them to found a Conjecture upon. And yet ’tis not improbable that thoſe great and noble Bodies have ſomewhat or other growing and living upon them, though very different from what we ſee and enjoy here. Perhaps their Plants and Animals may have another ſort of Nouriſhment there. Perhaps the Moiſture of the Earth there is but juſt ſufficient to cauſe a Miſt or Dew, which may be very ſuitable to the Growth of their Herbs. This I remember is Plutarch’s Opinion, in his Dialogue upon this Subject. For in our Earth a very little Water drawn from the Sea into Dew, and falling down again upon the Herbs, would be ſufficient for all our Needs, without any Rain or Showers. But theſe are mere Gueſſes, or rather Doubts, but yet they are the Jupiter’s and Saturn’s Moons turn always the ſame Side to them. beſt we can make of this, and all thoſe other Moons: for, as I ſaid before, they are all of the ſame nature, which is proved likewiſe by this, that as our [[134]]Moon can afford us the Sight never but of one Side of her, ſo they turn always the ſame Face to their primary Planets. It may perhaps ſeem ſtrange, how we ſhould come to know this; but ’tis no hard matter, after that Obſervation which I juſt now made, that the outermoſt of Saturn’s Moons can never be ſeen but when ſhe is on the Weſt-ſide of her Planet. The reaſon of which is plainly this, that one Side of her is darker, and does not reflect the Light ſo much as the other, which when it is turned towards us, we cannot ſee by reaſon of its weak Light. This always happening when ’tis Eaſt of him, and never on the other Side, is a manifeſt proof that ſhe always keeps the ſame Side toward Saturn. Now ſince the outermoſt of Saturn’s and our Moon carry themſelves thus to the Planets round which they move, who can well doubt it of all the reſt round Jupiter and Saturn? And there’s a very good reaſon for it, namely, that the matter of which thoſe Moons conſiſt, being heavier, and more ſolid on the Side that is averſe from us, than on [[135]]that which we have the Sight of, does conſequently fly with a greater force from the Centre of its Orbit: for otherwiſe, according to the Laws of Motion, it ſhould turn the ſame Side always, not to its Planets, but to the ſame fix’d Stars.
This Poſition of the Moons, in reſpect of their Planets, muſt occaſion a great many very ſurprizing Appearances to their Inhabitants, if they have any, which is very doubtful, but may for the preſent be ſuppos’d. An enquiry into our Moon may ſerve for all the reſt. Its Globe is divided into two Parts, in ſuch a manner, that thoſe who live on one Side never loſe the ſight of us, and thoſe on the other never enjoy it. Except only ſome few who live on the Confines of each of theſe, who loſe us, and ſee us again by turns. The Earth to them muſt ſeem The Aſtronomy of the Inhabitants of the Moon. much larger than the Moon doth to us, as being in Diameter above four times bigger. But that which is moſt ſurprizing, is, that Night and Day they ſee it always in the very ſame part of the Heaven, as if it never moved: ſome of them as if ’twas falling [[136]]upon their Heads: others ſomewhat above the Horizon, and others always in the Horizon, ſtill turning upon it ſelf, and preſenting them every twenty ſour Hours with a View of all its Countries, even of thoſe that lie near the Poles (I could wiſh my ſelf in the Moon only for the ſight of them) yet unknown and undiſcovered by us. They have it in its monthly Wane and Increaſe, they ſee it half, and horned, and full, by turns, juſt as we do the Body of the Moon. But the Light that they receive of us is five times larger than what we receive from them. So that in dark Nights that part that hath the Advantage of being towards us, receives a very glorious Light from us, tho’ Kepler thought otherwise. Their Days are always of the ſame Length with their Nights; and the Sun riſing and ſetting to them but once in one of our Months, makes the time both of their Light and Darkneſs to be equal to 15 of our Days. If their Bodies were of the ſame Materials with ours, thoſe that have the Sun pretty high in their Horizon, would be almoſt roaſted [[137]]in ſuch long Days. For the Sun is not farther from them than he is from us. This will be the Caſe of thoſe that live upon the Borders of the two Hemiſpheres we mentioned; but thoſe that live under the Poles of the Moon will be juſt about as hot as our Whale-fiſhers about Iſland and Nova Zemla are, in the Summer-time: who are in ſo little danger of being roaſted, that in the middle of their Summer, in their Days of three Months length, they very often find it extreme Cold. I call thoſe the Poles of the Moon, round which the fix’d Stars ſeem to turn to its Inhabitants, which are different from ours, and alſo from thoſe of the Ecliptick, although they move round theſe latter, at the diſtance of five Degrees, in a period of nineteen Years. Their Year they count by the Motion of the Stars, and their return to the Sun, and ’tis the ſame with ours. They can eaſily do it, becauſe they have the Stars Day and Night, notwithſtanding the Light of the Sun: for they have no Atmoſphere (which is the only reaſon that we don’t every [[138]]Day enjoy the ſame Sight) to hinder their Obſervations. Nor have they any Clouds to obſtruct their View, ſo that it is eaſier for them to find out the Courſes of the Planets, but more difficult to make a true Syſtem of them. For they will be apt to lay a wrong Foundation, by ſuppoſing that their Earth ſtands ſtill, which will lead them into more dangerous Errors than This may be applied to the Moons about Jupiter and Saturn. ever it did us. All that I have ſaid belongs as well to Jupiter’s and Saturn’s Satellites as to our Moon, in reſpect of the Planets they move round. The Length of their Day and Night is always equal to the Time of their Revolution: For example, the fifth Moon moves round Saturn in 80 Days, and the Days and Nights there are equal to Forty of ours. Both their Summer and Winter (Saturn moving round the Sun in thirty Years) are fifteen Years long. Therefore it is impoſſible but that their way of living muſt be very different from ours, having ſuch tedious Winters, and ſuch long watching and ſleeping times.