This would be a much easier question if you knew why the summer solstice is so important, then you need to know that a Gnomon is not one of those short little ceramic guys that you nestle into your garden who looks like he is waiting for Snow White, add a little personal history about Mr. Toscanelli and then go plop yourself down in the center of the mammoth church in the city center of Florence. Armed with all this information you would be able to explain the similarities – wa la, no problemo!
This summer event, calculated to be between June 20 and 22 for the northern hemisphere, has been tracked and celebrated throughout time. It was always viewed as part of a cycle that was to be honored and revered. Traditionally thought to be a confirmation life, it was, and still is, frequently celebrated with holidays, festivals and rituals. Not to mention that it was used as an indicator of sowing and harvest times. And. It was the use of a gnomon is what made this tracking this time possible.
So what is a gnomon? It’s a rod or style oriented in such a way that its shadow, cast by the Sun’s rays, and it shows the hours on a sundial. It is often positioned to show the time from noon or midday (in Latin: meridies, hence the Italian meridiana, “sundial”). The gnomon function can also be performed by a thread (as in box sundials), or a simple hole in a suitably positioned plate through which the sun’s rays fall on an elongated surface marked with the hour lines or signs of the zodiac for tracking the Sun’s path during the year.
So why is Mr Toscanelli an element to this story? Paolo dal Pozzo Toscanell is a native of Florence in the late 1300’s and was a well known mathematician, astronomer and cosmographer. A colleague and friend of Brunelleschi, Leon Battista Alberti, the King of Portugal and even Christopher Columbus. Around 1468 Toscanelli devised the gnomon still to be seen in the Cathedral of Santa Maria del Fiore in Florence. It is a bronze plate which lets the sun enter into the dome high above the left transept, and it forms a shadow on a circular white marble slab let into the floor of the Cathedral, which records the summer solstice to a half-second.
Did U know that Santa Maria del Fiore, the cathedral in Florence Italy has a gnomon and it is one of the tallest in the world? With this antique device it is possible to calculate the exact moment of the Summer Solstice, using the shadow as it passes through a hole position 90 meters high in the Dome of the church. Such a large gnomon, besides being an instrument which measures the exact moment of the solstice and therefore an indicator of sowing and harvest times, was also probably used to work out whether the sun’s yearly path through the stars is constant.
What are you doing to celebrate the summer solstice?