The Creation and Constitution of the Firmament

Inspired by the Apologetics Commentary by Dr. Robert Sungenis in "The Catholic Apologetics Study Bible: Volume IV: The Book of Genesis Chapters 1-11"....

The Creation and Constitution of the Firmament – Job 37:18

“Can you, like Him, spread out the skies, hard as a molten mirror?” (Job 37:18)

In the early 17th century, when the Catholic Church was confronting the growing support for the Copernican (heliocentric) model of the universe, a Carmelite friar named Paolo Foscarini was censured—not just for supporting heliocentrism, but also for claiming that the heavens were thin and not solid.

Unlike today, the Church at the time took this idea very seriously. One of the reasons Foscarini’s views were condemned was because they directly contradicted Scripture, especially verses like Job 37:18, which describes the heavens as being "hard as a molten mirror"—not thin, not vaporous, but solid and strong.

The Church Fathers and theologians believed that Scripture spoke not only with divine authority about faith and morals, but also about the natural world. They held that God, as the Author of both nature and Scripture, would never lie to us. So when Scripture said the heavens were solid, this was not treated as poetic or symbolic, but as factual.

Job 37:18 vividly affirms this: it describes the heavens as something that God spread out, strong and firm like metal that has been cast or molded. This was seen as supporting the idea that the firmament—the sky above—is not empty or formless, but a real, created structure with substance.

This understanding is consistent with the long-standing geocentric and Christocentric view of the universe, in which the Earth is at the center and the heavens move around it. The idea of a solid firmament that was eventually spread out into an ethereal space fits this model, reflecting a cosmos where everything has its God-ordained place and structure.

Interestingly, even modern science has shown that space is not completely empty, as once thought. It is filled with extremely fine and dense forms of matter and energy. So, this ancient biblical description is not out of place in today’s scientific understanding—it reminds us that divine Revelation has always guided human knowledge toward truth, even when it challenges the assumptions of modern popular unproven theories of modern science.

The Nature of the Firmament in Sacred Scripture

The "firmament" described in Genesis and elsewhere in Scripture refers to the entire expanse between the Earth and the outermost bounds of the universe. It is the vast region into which God placed the stars, planets, sun, and moon.

This firmament is not simply "space" as we think of it today—an empty void—but rather a created structure with form and substance. If space were, in fact, nothing, then there would be no space between any object from another. Also, the sacred authors, under divine inspiration, chose a specific word for it that emphasizes its firmness and order. They did not use other Hebrew terms that might imply simple distance or airy openness. Instead, they spoke of the heavens as something hard and as something spread out and ethereal.

This is why translators have consistently used the word “firmament” to describe this part of creation—a term that conveys both strength and malleability. In other parts of Scripture, the firmament is described as something that has been hammered out or stamped, like metal being shaped and formed. This imagery gives us a powerful understanding: the heavens are not formless or chaotic but were crafted by God with intention, strength, and purpose.

Scripture presents a mysterious duality: the heavens are both rigid and flexible. To the eye, the sky may seem open and empty, yet divine revelation tells us that it possesses an underlying solidity—a hidden strength not immediately apparent to human observation.

This very understanding was affirmed by the Church during the time of Fr. Paolo Foscarini, when his claim that the heavens were "thin and tenuous" was rejected. The Church, relying on the firm witness of Scripture, held to the truth that the heavens, while appearing transparent, are in fact composed of a real and enduring substance.

Unlike certain modern or Protestant interpretations that reduce the firmament to a simplistic solid shell or a purely symbolic image, the Catholic understanding—rooted in both faith and reason—respects the full richness of Scripture. It upholds that God's creation, including the heavens above, reflects both His power and His order. What science may later observe in part, the Church has long held in whole through the sacred deposit of faith.