By Daniel B. Gallagher

Around the corner from my old office in the Apostolic Palace is the Torre dei Venti, a sixteenth-century tower housing the sundial Pope Gregory XIII used to correct the Julian calendar. Aided by a team of brilliant Jesuits, Gregory tracked the movement of sunlight across the floor to ascertain the precise timing of the vernal and autumnal equinoxes. This led to the removal of ten days from the month of October in 1582. With very few exceptions (Iran being one of them), the "Gregorian calendar" has been the standard mode of computing the annual cycle ever since.

Few people know that the Vatican continues to collect astronomical data assiduously for the international scientific community. Its primary instrument is the Vatican Advanced Technology Telescope (VATT) located in southeast Arizona, which observes light in the optical and infrared ranges. Among the notable discoveries made by VATT are astronomical bodies in our neighboring Andromeda Galaxy called Massive Compact Halo Objects (MACHOs), which may help explain the presence of the mysterious and controversial "dark matter" that keeps our galaxy together – "dark" because it does not emit, absorb, or reflect light, and is thus invisible to telescopes.

A public-school product of the 1970s, I had neither heard of Gregory XIII nor known of the Vatican Observatory's existence. My fourth-grade teacher taught me that Columbus set sail to prove Catholic monarchs wrong for believing the world was flat and that Galileo was locked up for thinking the sun was at the center of the universe. The former is patently false, and the latter is a gross simplification.

Georges Lemaître, the twentieth-century priest and astronomer, was also entirely unknown to me until I took an astronomy class in college. It was Fr. Lemaître who first hypothesized that the universe was formed from a single particle that exploded at a definite point in time. His theory, which eventually became known as the "Big Bang" theory, continues to emerge as the best cosmological model for explaining the expanding universe.

I've been obsessed with space exploration ever since watching the Apollo 17 mission unfold on television, an event I am barely old enough to remember. So, it was only with great enthusiasm that I listened to NASA recently announce plans for a permanent lunar base. The Artemis II mission is, even as this column appears, carrying a crew around the Moon. If all goes according to plan, we'll be watching humans walk on the moon again in 2029.

In 1969, Pope Paul VI hailed the famed Apollo 11 mission for opening "a threshold to the wide expanse of boundless space and new destinies." The saintly pontiff entrusted a handwritten copy of Psalm 8 to astronauts Armstrong, Aldrin, and Collins to be left on the Moon. There it still sits, silently proclaiming, "I will sing of your majesty above the heavens with the mouths of babes and infants."

How easy we forget the primacy of "singing God's majesty" in the Christian life. "Praise," we read in the Catechism, "is the form of prayer which recognizes most immediately that God is God." (2639) If we principally know God from His works and praise Him thereby, how much more elevated our praise should be when we recognize the grandeur of His works.

In Dante's Paradiso, Beatrice directed the pilgrim's gaze to the Moon to demonstrate the insufficiency of man's sensory and intellectual powers for understanding Paradise. Three centuries later, Galileo pointed his telescope at the Moon and found it irregular and mountainous, something that deeply troubled the prevailing opinion that the Moon was perfectly smooth and reflective of the Earth's surface. In a famous letter to the Grand Duchess of Tuscany, Galileo lamented that his detractors "seemed to forget that the increase of known truths stimulates the investigation, establishment, and growth of the arts; not their diminution or destruction."

By "the arts," Galileo meant everything that contributed to t...