Every year, in the days around the summer solstice, June 21th, a magic happens. It’s a ray of sunlight that clearly appears in the Duomo.

This phenomenon is due to an astrological instrument called gnomon created in 1475 by Florentine mathematician Paolo dal Pozzo Toscanelli to measure the position of the sun and to determine the duration of the solar year.

Gnomon is the name of the part of a sundial that casts the shadow to mark the time of the day. But it can also be, as in this case, a hole that let the sunlight pass through in a darkened environment so to trace a well defined circle on the floor.

The one in Santa Maria del Fiore Cathedral is a 5 cm large and 9 meters high hole in the ceiling and it give life to an event happening just a few days a year, in a determined time of the day.

In 2016 the event will occur in the following days of June: 9, 16, 17, 21 and 25, from 12.30 to 1.30 PM.

If you want to know more have a look to the Opera del Duomo website: http://operaduomo.firenze.it/en/event/r/4-the-gnomon