An original theory or new hypothesis of the universe /

by Thomas Wright

LETTER the FOURTH.

Of the Nature of the heavenly Bodies continued, with the Opinions of the Antients concerning the Sun and Stars.

SIR,

Y

You tell me you begin to be a tolerable good Copernican, and would now be glad to have my Opinion further upon the Nature of the Sun and Stars, with regard to the Suggestion of their being like Bodies of Fire. This you say will go a great Way towards confirming you in the Notion you have begun to embrace of a Plurality of Systems, and a much greater Multiplicity of Worlds than our little solar System can admit of. Besides, shewing in a very evident Light, that the Authorities cited in my first Letter are founded upon the clearest Reason.

Anaxagoras, you say, believed the Sun to be a Lump of red-hot Iron; Euripides thought it a Clod of Gold; and others still more ridiculously have imagined it to be a dark Body, void of all Heat. That the Sun is a vast Body of blazing Matter, notwithstanding the various Opinions of those primitive Sages, will, I think, hardly admit of a Question: Since the known Warmth of his prolifick Beams, and the visible Effect of the Burning-glass, puts it quite out of the Power of our present Set of Senses, at least to argue against it; and how reasonably we may imagine the Stars to be all of the same or like Nature, will sufficiently appear from these following Considerations: First, it is well known to all Mathematicians, that any visible Object of any determined Magnitude may be reduced to the Appearance of [P]a physical Point, by removing the Eye of the Observer to a proper or proportionable Distance from it, within the finite View: And that the apparent Diameter of every luminous celestial Body, will always be diminished reciprocally, in Proportion to the Distance from the Eye, till they become altogether imperceptible.

[P] What is here meant by a physical Point, is a Point visible to the naked Eye, which human Art cannot divide; and so far it partakes of the Property of a mathematical one, which is only to be conceived, and not seen.

Thus the Disk of the Sun, which appears to us at Earth under an Angle of about half a Degree, if seen from the Planet Saturn, would appear not much bigger than the Planet Venus or Jupiter, in their most neighbouring Vicinity does to us; and consequently to an Eye placed in the Aphelion Point of the Orbit of the great Comet of 1680, his apparent Diameter would be so reduced as to seem but little bigger than the largest of the Stars; and by the same Analogy, or Way of Reasoning, admitting Space and Distance infinite, which I humbly apprehend is not to be disputed, were all the Matter in the Universe united, and conglobed in one Mass, with respect to ocular Sensation, it might be diminished so near to a mathematical Punctum, as to be almost adequate to our Ideas of Nothing.

This to any tolerable Optician, must be an evident Conviction of the Truth of the modern Astronomy, which now universally allow all those radiant Bodies the Stars to be of the same Nature with the Sun; and that as certainly they are no other than vast Globes of blazing Matter, all undoubtedly shining by their own native Light.

But as you have often objected to what has been said of the Distance of the Stars in general, and may possibly from a Supposition, that they are, or may be, much nearer to us, infer, that their Light, like that of the Planets, may be also borrowed from the Sun, or from some other radiant Body, which, from the Nature of the Supposition, must of Consequence be invisible to us, I judge it will not be amiss to throw a few demonstrative Arguments in your Way, in order to lead you a little out of the Path of an early Prejudice, and draw you as it were by Degrees through the Dawn of astronomical Reasoning, out of your original Error, and rescue your Imagination from the false Notions imbibed from Phænomena only in your younger Years. This I guess cannot fail of reconciling you to this more rational Way of Thinking, and make you acquainted with Truths of much Consequence, which perhaps you have yet been an intire Stranger to. The grand Deceptio Visus, which I must first endeavour to remove, and which as a sort of Paradox in Nature, has, as I may say, imprisoned the Understanding of many superficial Reasoners, and in general all incurious Men, is this.

Most People are too apt to think originally, that as the Heavens appear to be a vast concave Hemisphere, that the Stars must of course, as of Consequence, be fixed there, like so many radiant Studs of Fire, of various Magnitudes; and take it for granted, chiefly designed for no other Purpose than to deck and adorn the Canopy of our Night. This was long ago the Opinion of Thales the Milesian, and wants not the Authority of many of the Antients to back it. Others, in particular [Q]Ptolomy of Pelusium in Africa, who from his Experience in this Science, is called by some the Prince of Astronomers, believed them to be Loop-holes in the vast solid celestial Firmament, emitting the Light of the Crystalline Heaven through it to all within it. The famous Diogenes, Cotemporary with Plato, conceived them to be of the Nature of Pumice-stones, and inclined to an Opinion, that they were the Spiracula, or Breathing-holes of Heaven. Anaxagoras thought them Stones snatched up from the Earth by the Rapidity of its Motion, and set on Fire in the upper Regions above the Moon.

[Q] Ptolomy supposed two Heavens above that of the fixed Stars, which he called the eighth; viz. a ninth, the Crystalline, and a tenth the Primum Mobile. See Letter the second.

The sacred Sun, above the Waters rais'd,

Thro' Heav'ns eternal, brazen Portals blaz'd;

And wide o'er Earth diffus'd his chearing Ray,

To Gods and Men to give the golden Day.

But how ridiculous and absurd all these Opinions and Conjectures really are, will easily appear, if we but once consider the Nature of an unbounded Æther, and the amazing Property of infinite Space.

This, with what has been said before, will not a little assist your Imagination towards conceiving the Reasonableness of the Notion modern Astronomers are now confirmed in, of their being absolutely so many burning Balls, and which was no doubt, many Years ago, the Opinion of Manilius, as is evident from these Lines in his Poem of the Sphere.

For how can we the rising Stars conceive

A casual Production; or believe

Of the chang'd Heav'ns the oft renascent State

Sol's [R]frequent Births, and his quotidian Fate.

And again, in the same Poem:

The fiery Stars, and Æther that creates

Infinite Orbs, and others dissipates.

[R] Xenophanes believed the Stars to be no other than Clouds set on Fire, quenched in the Day-time, and rekindled in the Night.

Zoroaster, the first of all Philosophers we read of who studied the Stars, is reported to have believed them of a fiery Nature. Empedocles judged them to be Fire æthereal, struck forth in its Secretion, and blazing in the upper Regions. Plato thought them Fire, with the Mixture of other Elements as Cements. Heraclides Worlds by themselves, of Earth, Air, and Fire; and Aristotle, simple Bodies of the Substance of Heaven, but more condensed.

But that I may not take up too much of your Time with Opinions that has been imbibed in the Infancy of Astronomy, and has long ago been exploded, I shall attempt but one Thing more to confirm your Sentiments in this new Doctrine.

First, that the Stars are all at a Distance, not to be determined by the utmost Perfection of human Art, is manifest from their having very little, or no sensible [S]Parallax; and consequently, that any one of them is absolutely bigger or less than another, from the simple Laws of Opticks, cannot possibly come under our Observation to be ascertained; but that they all of them may be nearly of the same Size or Solidity, is as impossible, with any Shew of Reason to deny, since it is a known Principle in Geometry, that all visible Objects naturally diminish, as has been said before, or are magnified in a certain Proportion to their Distance from the Eye; and hence we may conclude, and not without Reason in its strongest Light to support us, that the smallest Stars, to the very least Denomination, are only removed respectively more distant from the Observer's Station; and that at least this we may be certain of, that they are all together undoubtedly an Infinity of like Bodies, distributed either promiscuously, or in some regular Order throughout the mundane Space: And, as Marino says,

Resplendent Sparks of the first Fire!

In which the Beauty we admire,

And Light of those eternal Rays,

The uncreated Mind displays.

[S] Mr. Bradley, Astronomer-Royal, has, in a great measure, proved that the Aberration of the Stars hitherto mistaken for a Parallax, may arise from, and indeed seems to be no other than the progressive Motion of Light, and Change of Place to the Eye, arising from the Earth's annual Motion and Direction.

It remains now I think to shew, and endeavour to prove, that the Stars are not only light Bodies of the Nature of the Sun, but that they are really so many Suns, all performing like Offices of Heat and Gravity, in a regular Order, throughout the visible Creation, in opposition to an Opinion you have formerly hinted at, of their being in another Sense of a secondary Nature.

All Objects within the sensible Sphere of the Sun's Attraction, or Activity, are in some measure magnified by a good Telescope: But the Stars are all placed so far without it, that the best Glasses has no other Effect upon them than making them appear more vivid or lively, but all innate opaque Bodies, reflecting only a borrowed Light from some primary one, contrary to this Property, are all observed to lose their Light, in the same Proportion, as they are magnified, and through all Glasses become more dull than otherwise they appear to the naked Eye: And hence we may infer, without any further Evidence, that the Stars are all light Bodies endowed with native Lustre; and that Bodies, like the known Planets, from the same Reasoning, it is as clear they cannot be, because their Distance, though uncertain as to the Truth of the whole, yet such a Part of it as cannot be denied, would render them all in such a Case invisible.

A Proof of this will plainly present itself, if we consider the Course of the known Comets, who all of them, without Exception, become imperceptible, and intirely disappear; though most of them much bigger than the Earth, or any of the lesser Planets, long before they arrive at their respective Aphelions.

But we are under a kind of Necessity to believe them either Suns or Planets, that is either dark or light Bodies; and since I have shewn the Improbability; nay, I may venture to say, the Impossibility of their being the first, it is natural sure to conclude, that they must be of the last Sort; and I am persuaded, if you but once consider how ridiculous it is to imagine so vast a Number of Bodies, all rolling round a Number of invisible Suns, which must otherwise be the Case, since they are seen on all Sides of ours, and cannot possibly be enlightened by him, or any, how all of them, by any one else, you cannot possibly have any sort of Difficulty in this Determination: But that no Arguments may be wanting to enforce your Belief of what is here concluded, it will not be amiss to put you in Mind of an optical Experiment or two, which cannot fail of convincing you of the vast Probability of what is here asserted of them; and next to a moral Certainty, demonstrate the Truth of what so many of the best Astronomers have advanced, as before namely, that the Stars are all, or most of them, Suns like ours.

Place any concave Lense before your Eye, and you will find all visible Objects will appear through it, as removed to a much greater Distance than they really are at, and reciprocally as much diminished. Now, if you look upon one of these Glasses of a proper Concavity, opposed to the Sun or Moon, you will respectively have the Appearance of a real Star or Planet, the first exhibited by the Body of the Sun, the other by the Moon, and either more or less diminished in Proportion to the Surface of the Sphere the Glass is ground to.

For Example, a double Concave, or Glass of a negative Focus, ground to a Sphere of about three Inches Diameter, will if opposed to the Sun's Disk at a proper Distance from the Eye, help you to a very good Idea how the Sun appears to the Planet Jupiter; and if a proper Regard be had to the Distance of the Planet Saturn, a Lense still more concave may be formed to give a just Idea of the Sun's Appearance to Saturn. Again, one much more concave than the former, proportioned to the Orbit of Mars, will naturally exhibit the solar Body, as seen from that Planet.

To the Planet Venus and Mercury, the Sun appearing much larger than to us at the Earth, to have any tolerable Notion of his varied Phænomena to them, it will be necessary to procure Glasses of a suitable Convexity, ground to reciprocal Concaves, which may easily be done to any Focus, so as to shew how the Sun, naturally appears to the Inhabitants of those two Planets.

The various Appearances of the Planets themselves to us at the Earth, may also well enough be had, if through Glasses analagous to their respective Distance and Magnitude, we look at the Moon, particularly all the Phases of Venus, and even of Mercury, and the Gibosity of Mars, &c. may be justly and beautifully represented at different Ages of the Moon, as those Planets appear through the largest and best Telescopes.

This Way you may convince even your Friend * * *, who you tell me has reasoned all his Senses useless, and yet continues so great an Atheist in Astronomy, as not to believe the World turns round upon its Axis, though he gives no better Reason for it than that of his not being giddy.

After all these Arguments, I hope no new Difficulties will arise to retard your Belief, or deprive the Stars of their solar Nature, so justly due to them: This Point gained, the next Thing to be considered is, whether all those glorious Bodies, the far greater Part of whom being invisible to the naked Eye, were made purely and purposely for the sole Use of this diminitive World, our little trifling Earth.

——Men, conceited Lords of all,

Walk proudly o'er this pendent Ball,

Fond of their little Spot below,

Nor greater Beings care to know,

But think those Worlds, which deck the Skies,

Were only form'd to please their Eyes.

The very Supposition not only implies a profound Ignorance of the Divine Attributes, but is as impious, and full of Vanity, as it is erroneous and absurd, and even a Blindness sufficient of itself, were there no other Cause for it, to introduce Idolatry in the Minds of Mortals, by sinking the divine Nature so near to the human.

It being granted that the Stars are all of the same Kind, I think it may be agreed, that what we evince of any one may be allowed to be true of any other, and consequently of all the rest. This Postulata gained, I shall next proceed to enquire what the real Use and Design of so many radiant Bodies are, or may be made for.

The Sun we have justly reduced to the State of a Star, why then in Reason should he have his attendant Planets round him, more than any of the rest, his undoubted Equals? No Shadow even of a Reason can be given for such an Absurdity.

May we not with the greatest Confidence imagine, that Nature as justly abhors a Vacuum in Place, as much as Virtue does in Time? Surely yes: And by supposing the Infinity of Stars, all centers to as many Systems of innumerable Worlds, all alike unknown to us; how naturally do we open to ourselves a vast Field of Probation, and an endless Scene of Hope to ground our Expectation of an ever-future Happiness upon, suitable to the native Dignity of the awful Mind, which made and comprehends it; and whose Works are all as the Business of an Eternity?

If the Stars were ordained merely for the Use of us, why so much Extravagance and Ostentation in their Number, Nature, and Make? For a much less Quantity, and smaller Bodies, placed nearer to us, would every Way answer the vain End we put them to; and besides, in all Things else, Nature is most frugal, and takes the nearest Way, through all her Works, to operate and effect the Will of God. It scarce can be reckoned more irrational, to suppose Animals with Eyes, destined to live in eternal Darkness, or without Eyes to live in perpetual Day, than to imagine Space illuminated, where there is nothing to be acted upon, or brought to Light; therefore we may justly suppose, that so many radiant Bodies were not created barely to enlighten an infinite Void, but to make their much more numerous Attendants visible; and instead of discovering a vast unbounded desolate Negation of Beings, display an infinite shapeless Universe, crowded with Myriads of glorious Worlds, all variously revolving round them; and which form an Atom, to an indefinite Creation, with an inconceivable Variety of Beings and States, animate and fill the endless Orb of Immensity.

That the sidereal Planets are not visible to us, can be no Objection to their actual Existence, and being there, is plain from this; it is well known, that the Stars themselves, which are their Central, and only radiant Bodies, are little more to us at the Earth, than mathematical Points. How ridiculous then is it to expect, that any of their small opaque Attendance, should ever be perceived so far as the Earth by us; and besides, to show the Impossibility of such a Discovery, we need only consider, what is, and what is not to be expected, or known in our own home System. All the Planets in this our sensible Region, every Astronomer knows, is far from being visible to one another, in every individual Sphere; for to an Eye at the Orb of Saturn, this Earth we live upon, which requires Years to circumscribe, and Ages to be made acquainted with, and is far from being yet all known, cannot possibly from the above Planet be seen: And further, since Saturn and Jupiter, two of the most material and considerable Globes we know of, except the Sun himself, are Bodies apparently of the same kind, and are observed to have each a Number of lesser Planets moving round them; why may we not expect with equal Certainty and Propriety, that all other Bodies, under the same Circumstances, are in like manner attended; that is, seeing the Sun is found to be the Center of a System of Bodies, all variously revolving round him? where lies the Improbability of his fellow Luminaries, the Stars, being surrounded in like sort, with more or less of such Attendance.

I shall offer but one Thing more to your Consideration in this Affair, and which I am in great Hopes will be sufficient to make you think these natural Suggestions a good deal more than probable, and that is this:

The modern Astronomers having, in a great measure, proved that the Stars are, in all respects, vast Globes of Fire like our Sun. Let us suppose a new-created Mind, or thinking Being, in a profound State of Ignorance, with regard to the Nature of all external Objects, but fully endowed with every human Sense and Force of Reason, suspended in Æther, exactly in the midway, betwixt [T]Syrius and the Sun; in which Case, both of these Luminaries would equally appear much about the Brightness of the largest of our Planets. Now should such a Being, determined either by Accident or Choice, arrive at this our System of the Sun, and seeing all the planetary Bodies moving round him, I would ask you what you think he would imagine to be round Syrius? Your Answer, I think I may venture to say, would not be nothing; and methinks I already hear you say, Why Planets such as ours.

[T] A Star of the first Magnitude in the greater Dog, and the most neighbouring to our Sun.