Thursday, January 8, 2015

Gnomons

The Bologna Duomo: home of the largest astronomical tool in the world: the 219 foot gnomen

The Duomo during the day. Photos are not allowed inside. Too bad as it contains lots of interesting stuff
A gnomen also known as an ecclestiastial meridian is a long brass line on the floor that a narrow slit of light (an oculus) can shine on. It can tell you what day of the week it is. An astronomer Cassini from the nearby University of Bologna had it installed in 1655. From this, he was able to determine the true length of a solar year. Why would the Catholic Church, usually an enemy of astronomy, agree to have an instrument of science installed into the floor? Well they needed to know when to celebrate Easter. Other cathedrals throughout the world have these also but the one in Bologna is the longest and thus the most accurate.

I looked for this while I was there and did not find it but I was looking for a sundial, not a straight line with markings on it. We came in between masses so we didn't have much time to explore. This Duomo has been the target of several terrorists threats because on the walls, there is a 500 year old fresco of Mohammed being devoured by demons. Again, I didn't see this and I am sure it is not advertised as a highlight given the propensity of certain individuals to kill in the name of their god (see Je suis Charlie).

I called this the half baked duomo as they never got around to finishing its fa├žade despite work was started 700 years ago. There were grand plans for this place. It was going to be larger than St. Peters in the Vatican until the Pope got wind of that and put an end to that.

Schools have been cancelled due to brutal windchills. And we will have more snow tonight. Yep I hate winter. I will go to the Y and run in circles.

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