The celestial worlds discover'd

by Christiaan Huygens

Fig. 5.

p. 139

[[139]]

Having thus explained the primary and ſecondary Planets round the Sun, we ſhould next ſet about the third Sort, the Sun and fix’d Stars; but before we do that, it would be worth while to ſet before you at once, in a clearer and more plain Method than hitherto, the Magnificence and Fabrick of the Solar Syſtem. Which we can’t poſſibly do in ſo ſmall a Space as one of our Leaves will but admit of, becauſe the Bodies of the Planets are ſo prodigiouſly ſmall in companion of their Orbs. But what is wanting in Figure ſhall be made up in Words. Going back then to the firſt Scheme, ſuppoſe another Fig. 1. like it, and proportionable, drawn upon a very large ſmooth Plain; whoſe outermoſt Circle repreſenting the Orb of Saturn, muſt be conceived three hundred and ſixty Foot in Semidiameter. In which you muſt place the Globe and Ring of Saturn of that Fig. 2. Bigneſs as the 2d Figure ſhows you. Let all the other Planets be ſuppoſed every one in his own Orbit, and in the middle of all the Sun, of the ſame Bigneſs that That Figure repreſents, [[140]]namely, about four Inches in Diameter. And then the Orbit or Circle in which the Earth moves, which the Aſtronomers call the Magnus Orbis, muſt have about ſix and thirty Foot in Semidiameter. In which the Earth muſt be conceived moving, not bigger than a grain of Millet, and her Companion the Moon ſcarcely perceivable, moving round her in a Circle a little more than two Inches Diameter, as in Fig. 5. the Figure here adjoined, where the Line A B repreſents a ſmall portion of that Circle which the Earth moves in: the ſmall Circle therein C is the Earth, and the Circle D E the Path of the Moon round it, in which the Body of the Moon is D.

The outermoſt of Saturn’s Moons moves in an Orbit whoſe Semidiameter is 29 Inches; that of Jupiter in a ſomewhat ſmaller, whoſe Semidiameter is 19 and a quarter.

And thus we have a true and exact Deſcription of the Sun’s Palace, where the Earth will be Twelve thouſand of its Semidiameters diſtant from him, which in German Miles makes above [[141]]ſeventeen Millions. But perhaps we may have a clearer Comprehenſion of this vaſt Length, by comparing it with ſome very ſwift Motion after the Example of Heſiod the Poet, who imagin’d that an Anvil let fall from the Top of Heaven, reach’d the Earth the tenth Day of its Journey, and in ten more arriv’d at the Bottom of Hell, the end of it: ſo making the Earth the mid-way between Heaven and Hell. I ſhan’t make uſe of the Anvil, but of ſomething as good, namely, a Bullet ſhot out of a great Gun, which may travel perhaps in a Moment, or Pulſe of an Artery, about a hundred Fathom, as is proved by thoſe Experiments that Merſennus in a Treatiſe of his relates; by which the Sound was found to extend itſelf eighty hundredth parts in the The immenſe diſtance between the Sun and Planets illuſtrated. ſame time. I ſay then, that ſuppoſing a Bullet to move with this Swiftneſs from the Earth to the Sun, it would ſpend 25 Years in its Paſſage. To make a Journey from Jupiter to the Sun, would require 125, and from Saturn thither 250 Years. This account depends upon the meaſure of the Earth’s [[142]]Diameter, which, according to the accurate Obſervations of the French, is 6538594 times ſix Paris Feet, one Degree being 57060 of that Meaſure. This ſhows us how vaſt thoſe Orbs muſt be, and how inconſiderable this Earth, the Theatre upon which all our mighty Deſigns, all our Navigations, and all our Wars are tranſacted, is when compared to them. A very fit Conſideration, and Matter of Reflection, for thoſe Kings and Princes who ſacrifice the Lives of ſo many People, only to flatter their Ambition in being Maſters of ſome pitiful Corner of this ſmall Spot. But to return to the matter in hand, now we have given you an account of the Sun’s proportion to thoſe Orbs and Bodies, we’ll ſee what more we can ſay of him.

No ground for Conjecture in the Sun. And ſome have thought it not improbable but that the Sun himſelf has alſo his Inhabitants. But upon what reaſon I cannot imagine, there being leſs ground for a Probability in him than in the Moon. For we are not yet ſure, whether he be a ſolid or liquid Globe; altho’, if my Notion of Light [[143]]be true, upon that account I ſhould rather think him liquid: which his Roundneſs and equal diſtribution of his Light to all parts are an Argument for. For that very ſmall inequality on his Surface, which is diſcovered by the Teleſcopes, (and that not always neither) which makes Men fancy they ſee boiling Seas and belching Mountains of Fire, is nothing but the trembling Motion of the Vapours our Atmoſphere is full of near the Earth; which is likewiſe The Faculæ in the Sun not eaſily ſeen. the Cauſe of the Stars twinkling. Nor could I ever have the Luck to diſcern thoſe bright Spots in the Sun which they boaſt as much of as they do of his dark ones, which latter I have very often ſeen; ſo that I have very good Reaſon to doubt whether there be any thing in the Sun brighter than the Sun itſelf. For by the moſt exact Obſervations, I could never find any ſuch pretended to be ſeen any where but juſt about his dark Spots; and it is no great wonder that thoſe Parts which are ſo near the darker, ſhould appear ſomewhat By reaſon of its Heat no Inhabitants like ours can live in the Sun. brighter than the reſt. That the Sun is extremely hot and fiery, is beyond [[144]]all diſpute, and ſuch Bodies as ours could not live one Moment in ſuch a Furnace. We muſt ſuppoſe a new ſort of Animals then, ſuch as we have no Idea or Likeneſs of among us, ſuch as we can neither imagine nor conceive: which is as much as to ſay, that we can make no Suppoſition at all about them. No doubt that glorious and vaſt Body was made for ſome noble End and Uſe, and fram’d with excellent Deſign. And I think we all very well know and feel its Uſefulneſs in that effuſion of Light and Heat to all the Planets round it; in the Preſervation and Happineſs of all living Creatures, and that not only in our Ball, but in thoſe vaſt Globes of Jupiter and Saturn, not contemptible when compared with its own. Theſe are ſuch great, ſuch wiſe Ends, that it is not ſtrange that the Sun ſhould have been made, if it had been only upon their account. For, as for Kepler’s Fancy, that he hath another Office, namely, to help on the Motion of the Planets in their own Orbs, by turning about his own Axis (which he would fain eſtabliſh in his Epitome of the Copernican [[145]]Syſtem) I ſhall give good Reaſons why I cannot aſſent to it.

The ſix’d Stars so many Suns. Before the Invention of Teleſcopes, it ſeemed to contradict Copernicus’s Opinion, to make the Sun one of the fix’d Stars. For the Stars of the firſt Magnitude being eſteem’d to be about three Minutes Diameter; and Copernicus (obſerving that tho’ the Earth changed its Place, they always kept the ſame diſtance from us) having ventur’d to ſay that the Magnus Orbis was but a Point in reſpect of the Sphere in which they were placed, it was a plain Conſequence that every one of them that appeared any thing bright, muſt be larger than the Path or Orbit of the Earth: which is very abſurd. This is the principal Argument that Tycho Brahe ſet up againſt Copernicus. But when the Teleſcopes took away thoſe Rays of the Stars which appear when we look upon them with our naked Eye, (which they do beſt when the Eye-glaſs is black’d with Smoke) they ſeemed juſt like little ſhining Points, and then that Difficulty vaniſhed, and the Stars may yet be ſo many Suns. Which is [[146]]the more probable, becauſe their Light is certainly their own: for it’s impoſſible that ever the Sun ſhould ſend, or they reflect it at ſuch a vaſt Diſtance. This is the Opinion that commonly goes along with Copernicus’s Syſtem. They are not all in the ſame Sphere. And the Patrons of it do alſo with reaſon ſuppoſe, that all theſe Stars are not in the ſame Sphere, as well becauſe there’s no Argument for it, as that the Sun, which is one of them, cannot be brought to this Rule. But it’s more likely they are ſcatter’d and diſpers’d all over the immenſe Spaces of the Heaven, and are as far diſtant perhaps from one another, as the neareſt of them are from the Sun.

Here again too I know Kepler is of another Opinion in his Epitome of Copernicus’s Syſtem, that we mention’d above. For tho’ he agrees with us, that the Stars are diffus’d through all the vaſt Expanſe of the Heavens, yet he cannot allow that they have as large an empty Space about them as our Sun has. For then ’twas his Opinion, we ſhould ſee but very few, and thoſe of very different Magnitudes: For, ſeeing [[147]]the largeſt of all appear ſo ſmall to us, that we can ſcarce obſerve or meaſure them with our beſt Inſtruments; how muſt thoſe appear that are three or four times farther from us? Why, ſuppoſing them no larger than theſe, they muſt ſeem three or four times leſs, and ſo on ’till a little farther they will not be to be ſeen at all: Thus we ſhall have the ſight of but very few Stars, and thoſe very different one from another; Whereas we have above a Thouſand, and thoſe not conſiderably bigger or leſs than one another. But this by no means proves what he would have it; and his Miſtake was chiefly, that he did not conſider the Nature of Fire and Flame which may be ſeen at ſuch diſtances, and at ſuch ſmall Angles as all other Bodies would totally diſappear under. A thing that we need go no farther than the Lamps ſet along the Streets to prove. For altho’ they are a hundred Foot from one another, yet you may count Twenty of them in a continued Row with your Eyes, and yet the twentieth Part of them ſcarce makes an Angle of ſix Seconds. Certainly [[148]]then the glorious Light of the Stars muſt do much more than this; ſo that it’s no wonder we ſhould ſee a Thouſand or two of them with our bare Eyes, and with a Teleſcope diſcover twenty times that number. But Kepler had a private Deſign in making the Sun thus ſuperiour to all the other Stars, and planting it in the Middle of the World, attended with the Planets: For his Aim was hereby to ſtrengthen his Coſmographical Myſtery, that the Diſtances of the Planets from the Sun are in a certain proportion to the Diameters of the Spheres that are inſcribed within, and circumſcribed about Euclid’s Regular Bodies. Which could never be ſo much as probable, except there were but one Chorus of Planets moving round the Sun, and ſo the Sun were the only one of his kind.