The Duomo’s gnomon marks the Summer Solstice

It’s that time of year again: Florence’s famous gnomon will work its astronomical magic for three days this month, as the Summer Solstice nears.

On June 21, 27 and 28, visitors to the Cathedral of Santa Maria del Fiore will be treated to a spectacular show, when the noon sun penetrates the church’s lantern and strikes the gnomon installed under the southern window of the lantern’s drum. The sun’s rays will pass through the small bronze tablet, which is cut with a hole 4 centimeters in diameter, forming a disk of light that aligns perfectly with a circular marble slab on the floor of the Chapel of the Cross, to the left of the main altar.

The gnomon found in Florence’s cathedral is one of the oldest astronomical tools in the world. According to a recently discovered document in the Opera di Santa Maria’s archives, the device was designed by the mathematician Paolo dal Pozzo Toscanelli in 1475 as a way to measure the position of the sun in the sky. At 90 meters up, it is the highest in the world, and one of the most accurate.

Access to the event, which will take place between 12.30pm to 1.30pm, is free, but reservations are highly recommended as spots fill up quickly (eventi@operaduomo.firenze.it | 055 2302885).