Credit: BRIDGEMAN ART LIBRARY

The Kings' comet

Giotto, Halley and the art of observation.

According to legend, it was 11 days after Christmas, on Epiphany, that the Kings brought their gifts to Christ. They arrived at precisely the right spot courtesy of a guiding star, whose behaviour differentiated it clearly from those normally visible in the night sky. If it was a star outside the normal run, what did it look like?

For most medieval artists, the conventional pointed star did the job well enough, hovering above the stable in which Christ had been born. But not so for Giotto di Bondone, the great early-fourteenth-century pioneer of naturalism. In his lucid and eloquent image of the Adoration of the Magi in the Arena Chapel in Padua, Giotto characterizes the Kings' guiding light as a flaming ball streaking across the heavens. The eight-pointed star at the centre of the array dissolves at its rear into a trailing tail of streaky fire. Less prominent than when first painted, through losing some of its painted gold, it still has a striking effect, unparalleled in earlier representations. It is easy to believe that Giotto had witnessed the advent of a comet. But which one?

By far the best candidate is Halley's comet, which was visible from mid-September to November in 1301. The date works well enough, for Giotto painted his image in the years immediately preceding 1305. The comet's visit was noted in various written records, and one Italian chronicler described it as having “great rays of smoke behind it”.

Giotto's ability to depict the comet so convincingly was due to his innovative naturalism. More than a century before the invention of linear perspective, he had experimentally determined how to create the effect of solid forms, overlapping in space, with simple architectural features slanted back into the picture. One important tool was his use of a consistently directional light, described as coming from a large window on the west wall of the chapel. Not only does Giotto use this light to sculpt the figures, but he also plots its passage on the stable, as the diagonal beams of the roof fall systematically into shade on its far side.

It is in this context that the comet declares itself in the spectator's mind as an observed phenomenon rather than a conventional pictorial symbol. Embedded precociously in Giotto's image is the as-yet unrecognized potential for the use of empirical science in the naturalistic techniques forged by the artists of the fourteenth and fifteenth centuries.

Giotto's portrayal of the appearance of a 'real star' could not be more fitting for Epiphany, given that the Greek epi means 'around' or 'over' and phainein 'appearance' or 'manifestation'. It was also a happy choice to name the spacecraft launched in 1986 to investigate Halley's comet after the great Italian artist.

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