Medieval and Renaissance religious paintings sometimes show flying saucers or UFOs floating in the sky behind the main figures: proof aliens have been visiting for centuries.

The most-circulated example is a painting in Florence's Palazzo Vecchio showing a disc radiating light in the sky above a bystander, popularly attributed to Domenico Ghirlandaio and titled Madonna with Saint Giovannino. Italian researcher Diego Cuoghi, who has published detailed iconographic analysis of these paintings (including in Skeptic magazine), notes the work is more properly attributed to Sebastiano Mainardi of Ghirlandaio's workshop, and that the glowing disc is not original invention but a standard "cloud of glory": a device lifted from the apocryphal Protoevangelium of James, used in period art to represent the presence of God. The same convention shows up in Carlo Crivelli's 1486 Annunciation with Saint Emidius at London's National Gallery, where a beam of light descends from a circular opening in the sky onto Mary: this is a visual rendering of the Holy Spirit's descent at the Annunciation, a standing motif art historians recognize across dozens of Annunciation paintings from the period, not a one-off anomaly.

A third commonly cited case, Aert de Gelder's 1710 Baptism of Christ, shows Christ and John the Baptist lit by rays descending from a disc overhead. De Gelder was a late follower of Rembrandt working in a firmly Christian devotional tradition; the disc reads straightforwardly as the parted heavens and the descending Holy Spirit described in the baptism narratives in all four Gospels, rendered in the same radiant-cloud convention as the other two paintings. None of these three motifs required later reinterpretation to be understood by their own century's viewers, they were legible religious symbols painted for patrons and clergy who knew exactly what they were looking at.

The oldest and most debated example predates the Renaissance entirely: a fourteenth-century Crucifixion fresco at the Visoki Dečani monastery in Kosovo, which shows two small figures riding in flame-shaped vessels flanking the cross. The claim that these are spacecraft dates specifically to the 1960s, when the French magazine Spoutnik and later Erich von Däniken's ancient-astronaut writing popularized the reading. Byzantine and Serbian art historians identify the figures as personifications of the sun and moon, a well-attested convention in Orthodox Crucifixion iconography meant to show the heavens themselves grieving at Christ's death; comparable personified sun-and-moon pairs appear in other medieval Serbian churches from the same tradition, which undercuts the idea that Dečani is a unique or inexplicable image.

Taken together, these cases share the same pattern: a real, documented iconographic convention (glory-clouds, the descending Spirit, personified celestial bodies) reinterpreted by modern viewers through a science-fiction lens the original painters and their audiences did not share. The objects in the paintings are genuine and worth looking at closely; the flying-saucer reading imposed on them is not what any art historian working on these specific paintings has found in the archival or theological record.