High noon: How the sun and moon guided prayer times and liturgy
A long granite strip running from the ancient obelisk through St. Peter's Square at the Vatican serves as a meridian, a line that indicates when the sun has reached true or solar noon and is at its highest point in the sky. (CNS/Paul Haring)
The 83-foot stone obelisk in the middle of the square acts as a sundial that can accurately indicate midday and the two solstices thanks to a granite meridian and marble markers embedded in the square.
Pope Benedict XVI proudly pointed out the hidden timepiece during an Angelus address he gave on the winter solstice a few years ago.
"The great obelisk casts its shadow in a line that runs along the paving stones toward the fountain beneath this window and in these days, the shadow is at its longest of the year," he told pilgrims from the window of his library.
In fact, at noon on Dec. 21, the obelisk's shadow falls on the marble disk furthest from the obelisk's base, while at noon on June 21 -- the summer solstice -- the tip of the shadow will fall just a few yards from the obelisk. In between are five other disks marking when the sun enters into which sign of the zodiac.
A long, thin granite strip running from the obelisk toward the pope's window and through one of the fountains acts as the meridian: a line that indicates when the sun has reached true or solar noon and is at its highest point in the sky.
The pope, in his solstice soliloquy, reminded people that the church has always been keenly interested in astronomy to help guide and establish fundamental liturgical days and the times of prayer such as the Angelus, which is recited in the morning, at noon and in the evening. While sunrise and sunset are easy to figure out, sundials could accurately tell midday, he said.
(Click on the above link for the whole story - if you're a geek like me!)