In 1629, twenty years after the telescope had first been turned to the heavens, launching an explosion of astronomical discoveries, a prominent supporter of Copernicus had something interesting to say about the stars.
And therefore it is clear enough, that the fixed stars… are the visible Armies of God. Each day he calls them by name, and leads them out by number. In them he exercises his power. Indeed they are, as it were, the strongest attendants, the guard of the Palace of God. They endure the approach of any number of human beings who stumble their way onto the palace grounds, yet they will most gladly open the way, when Our Lord Jesus Christ will appear, in order that he may raise us gloriously to himself, and stand us before the Throne of God.*
Philips Lansbergen. The Phillipus Lansbergen Public Observatory in Middleburg, Netherlands, is named for him.This description of the stars comes from Considerations on the Daily and Annual Rotation of the Earth by the Dutch Copernican Philips Lansbergen (Philippe van Lansberge). According to historian Rienk Vermij, Considerations was the first pro-Copernican book to be written for a popular, non-mathematical audience. It was published in Dutch but in 1630 a Latin version was published which attracted attention across Europe. Wikipedia calls the book a “best-seller.”
So why would a prominent Copernican, writing twenty years after the advent of the telescope, call the stars “the armies of God”? The answer to that is simple. He needed an explanation for why the stars were so giant.
For every single one exceeds not only the Earth, but also the sun, and generally the whole orbit of the Earth…. They stand in heaven by rank like giants, and mighty warriors, without any motion. For no one is able to move Earth, except God alone who has built it (Haggai 2:22), and likewise no one knows how to stir up these immense and very powerful bodies, except God who created them. Therefore they are truly great and powerful armies of God, through which He brings about anything He wills (Psalm 115:3).
Why does Lansbergen say that every single star exceeds in size not only the Earth, but also the sun, and generally the whole orbit of the Earth? Because that’s what the astronomical data said.
To a person with excellent vision, stars appear as small, round dots of differing apparent sizes, or magnitudes. Magnitude means bigness. In the nineteenth century the magnitude scale was redefined in terms of the irradiance or brightness of a star, but originally the scale was about the apparent size of a star. Thus you find statements like this in old books—
The fixed Stars appear to be of different Bignesses…. Hence arise the Distribution of Stars, according to their Order and Dignity, into Classes; the first Class… are called Stars of the first Magnitude; those that are next to them, are Stars of the second Magnitude… and so forth, ‘till we come to the Stars of the sixth Magnitude, which comprehend the smallest Stars that can be discerned with the bare Eye….
—or like this (talking about the changing magnitude of a nova)—
…from the sixteenth to the twenty-seventh of the same month… it changed bigness several times, it was sometimes larger than the biggest of those two stars, sometimes smaller than the least of them, and sometimes of a middle size between them. On the twenty-eighth of the same month it was become as large as the star in the beak of the Swan, and it appeared larger from the thirtieth of April to the sixth of May. On the fifteenth it was grown smaller; on the sixteenth it was of a middle size between the two, and from this time it continually diminished till the seventeenth of August, when it was scarce visible to the naked eye.
And regarding bigness, the first magnitude stars have an apparent diameter of roughly one fifteenth that of the moon. That’s what Tycho Brahe, Ptolemy, Al-Farghani, and Al-Battani all said. That’s what your neighbor—the one who knows nothing about astronomy but who has good eyesight and who is in the building trades and thus often makes measurement estimates by sight—will say if you ask him to look up at a bright star and at the waxing crescent moon and to tell you how many copies of that star could be lined up side-by-side between the two horns of the crescent.
Those stars are a problem for a heliocentric universe. Earth’s annual orbital motion about the sun should be reflected in the stars—an effect called annual parallax. No annual parallax of stars could be detected with the instruments of four centuries ago, so Copernicans assumed the stars were so distant as to make Earth’s orbit vanishingly small by comparison to the distance of the stars. Vastly distant stars would explain the lack of annual parallax.
Illustration from NASA of annual parallax. If the star is sufficiently distant, then the Earth’s orbit will be negligible by comparison, and no parallax will be observed.
Illustration of a star as seen through a telescope of very small aperture, by the prominent nineteenth-century astronomer John Herschel, showing its appearance of measurable size. The appearance is spurious, a result of the small aperture and the wave nature of light. If you wish to see this phenomenon yourself, cut a clean, round, dime-sized hole in a large piece of thin cardboard (like a cereal box). Aim your telescope at a bright star and focus it. Then place the cardboard over the aperture of your telescope, so the only light from the star to enter the telescope passes through the hole. If you can obtain pictures of the star both with and without the cardboard mask, send me copies at christopher.graney [at] vaticanobservatory.org and I will try to feature them in a future post.Now here comes the problem. As Brahe noted, for the stars to be so distant and yet appear the size they do, they would have to be extremely large—comparable to Earth’s orbit, and utterly dwarfing the sun. After Brahe’s death in 1601, telescopes showed naked-eye estimates of the apparent sizes of stars to be too large. But those early small telescopes still showed stars to have clearly measureable sizes. Moreover, those telescopes increased sensitivity to parallax, requiring stars to be still further away, and thus negating whatever improvement in the problem came from the smaller apparent sizes.
Johann Georg Locher in his 1614 Mathematical Disquisitions Concerning Astronomical Controversies and Novelties succinctly stated the Copernican star size problem. Locher, who also commented in his Disquisitions on how the telescope had called into question older estimates of star sizes, noted that the Copernican theory requires the Earth’s orbit to be imperceptibly small compared to the distance to the stars. However, he said, the stars themselves are of small but measurable size (not imperceptibly small) against the dome of the sky, and thus also of measurable size compared to their distance.** Since “small but measureable” is larger than “imperceptibly small,” every star must be larger than Earth’s orbit.
And that is why Lansbergen stated that every single star exceeds the size of not only the Earth, but also the sun, and the orbit of the Earth. And according to Lansbergen, this just points to the glory of God, and it is supported by scripture. All those huge stars must put out a lot of light, and that points to all the light God dwells in beyond the stars—
Indeed, if the light of one Sun may be so excellent that the eyes may not consider it without injury; how much stronger will be the light of the so many and so much brighter Bodies which are gathered together in the starry heaven? Therefore rightly the Apostle has said, 1 Timothy 6:16, God dwells in unapproachable light. For if the splendor of the starry sphere (which is the Atrium of the Divine Palace) may be so illustrious; how strong and unapproachable will be the Radiance of the Habitacle of the Divine Majesty itself?
The stars being God’s armies is also backed up by scripture, he says, with help from telescopic observations. First,
The fixed stars God has placed at a distance in the firmament, as an army…. thus the stars are the battling Armies of God, which obey and execute His orders.
After all, stars come in different ranks (magnitudes), and formations (constellations). And while one might have once objected that there are too few stars to comprise a great enough army for God—since we can see only a few thousand stars, and of course many human armies have boasted far greater numbers than that—Lansbergen notes that the telescope reveals there to be countless stars! And so, says Lansbergen,
it is again made clear that the Army of the Fixed Stars is not only great; but also greater than all armies which have ever been on Earth: so they may rightly merit to be called the Armies of the Lord.
And what scripture supports this? Isaiah 40:26, for one—
Lift up your eyes on high, and see who has created these: He leads out their army and numbers them, calling them all by name. By his great might and the strength of his power not one of them is missing.
—and the Canticle of Deborah and Barak, for another (Judges 5:20)—
From the heavens the stars, too, fought; from their courses they fought against Sisera.
At this point, O Reader, you may be thinking, “well, Lansbergen is an oddity—one Copernican with weird ideas.” Consider the figure at right, Thomas Digges’s famous 1576 illustration of the Copernican system in infinite space. Click on it and enlarge it. Note the words Digges writes among the stars:
The palace of felicity, garnished with perpetual shining glorious lights innumerable, far excelling our sun both in quantity and quality, the very court of celestial angels, devoid of grief and replenished with perfect endless joy, the habitacle of the Elect.
In the same work Digges writes regarding the starry heavens—
And this may well be thought of us to be the glorious court of the great God, whose unsearchable works invisible, we partly by these his visible, conjecture; to whose infinite power and majesty, such an infinite place, surmounting all other both in quantity and quality, only is convenient.
And when Tycho levelled the star size argument against the Copernican Christoph Rothmann, Rothmann wrote back that he did not care how large the stars had to be: “It reckons that the greater the King, so much more greater and larger the palace befitting his Majesty”—what could be too large a palace for God? Rothmann asked. And even Copernicus himself in his De Revolutionibus invoked the work of God when discussing the stars and the lack of annual parallax.
Yet none of these {parallax} phenomena appears in the fixed stars. This proves their immense height, which makes even the sphere of the annual motion, or its reflection, vanish from before our eyes. For, every visible object has some measure of distance beyond which it is no longer seen, as is demonstrated in optics. From Saturn, the highest of the planets, to the sphere of the fixed stars there is an additional gap of the largest size. This is shown by the twinkling lights of the stars. By this token in particular they are distinguished from the planets, for there had to be a very great difference between what moves and what does not move. So vast, without any question, is the divine handiwork of the most excellent Almighty.
Today we know that the stars are not all the size of Earth’s orbit or larger. A few stars are indeed that giant, but sun-sized stars are much more common, and the most common are stars smaller than the sun (the vast majority of stars are thought to be feeble little red dwarfs that put out but a small fraction of the sun’s light). Brahe, who thought giant stars were absurd, would no doubt be very satisfied to know this. The source of the star-size problem was an illusion—the wave nature of light causes light passing from a tiny source through a circular aperture (like a small telescope lens) to spread out, creating a spurious appearance of a much larger physical size (such as is seen in the Herschel sketch above). You can measure the apparent size of a star, either by means of your eye or by means of a small telescope, but that apparent size tells you nothing about the actual size of the star.
Why did Lansbergen not consider that perhaps something was amiss regarding the star sizes? To be fair, astronomers would struggle with the star-size issue for almost a century after Lansbergen’s Considerations first appeared. But still, stars as God’s armies? The giant, battling, guardians of the gates of heaven? God’s infinite power and majesty on display? Twenty years after Considerations, the Italian astronomer Giovanni Battista Riccioli—a Jesuit, and an anti-Copernican—would say regarding such ideas that, while no one can deny the power of God, they do not satisfy the more prudent person. Was there not a better answer to the stars question in 1629 than a direct appeal to the infinite?
*I refer those readers who want full details regarding the translations of Lansbergen and others in this post to “Stars as the Armies of God,” Journal for the History of Astronomy (2013), or to the chapter by the same name in Setting Aside All Authority (2015).
**Suppose a star has apparent size a. The star’s physical size is then s=πr(a/180°), where r is its distance and a is measured in degrees. Thus s/r is proportional to a/180°, or s bears the same ratio to r as the apparent size of the star bears to the entire dome of the sky (180° from horizon to horizon). Meanwhile, a star’s parallax is determined by the ratio between the size of Earth’s orbit and r. Therefore, so long as a star’s parallax cannot be detected, but its apparent size can be detected, the star’s physical size must exceed the size of Earth’s orbit.
