If you’ve never heard of Ignazio Danti, don’t feel too bad; Austin College physics professor Donald Salisbury hadn’t head of him either when he first became interested in the early European astronomy scene. A priest by trade, mathematician by inclination, and astronomer by hobby, Danti has been — excuse the pun — eclipsed in most history books by contemporaries like Galileo and Copernicus.

If you’ve never heard of Ignazio Danti, don’t feel too bad; Austin College physics professor Donald Salisbury hadn’t head of him either when he first became interested in the early European astronomy scene. A priest by trade, mathematician by inclination, and astronomer by hobby, Danti has been — excuse the pun — eclipsed in most history books by contemporaries like Galileo and Copernicus.


But for all his contributions to science and architecture in Italy in the 1500s, it was something Danti didn’t do, or at least something he didn’t finish, that led to a little piece of his legacy at Austin College’s new IDEA Center, a state-of-the-art science building that opened last August.


"I had developed an interest in Galileo and his times, and I began to put together courses in which we discussed Galilieo’s contributions to modern science," explained Salisbury. "I decided to explore even further and learn more about the context in which he made his discoveries, and that’s when I came across Ignazio Danti, who had designed this gnomon for the Santa Maria Novella (Church in Florence)."


To create his gnomon — a kind of solar calendar — Danti poked a pair of holes in the masonry of the Santa Maria Novella to allow pinpoints of sunlight into the chapel at a certain angle. Danti planned to create a meridian line inside the chapel that would mark solstices and equinoxes on the church floor by using the sunbeam’s location, but he left town before the project was complete.


"Two years later he did build one in Apollonia," said AC Physics Chair David Baker, "but it unfortunately wasn’t as accurate as it needed to be. Instead of the meridian line being true north-south, it was nine degrees off."


When it came time to design the IDEA Center, Salisbury enlisted Baker’s help to accomplish what Danti hadn’t: an accurate solar gnomon. But trying to fit a 69-foot meridian line among the pillars and curved glass of the building’s atrium proved challenging.


"In order to make sure that we got this meridian line correct, during construction of the building, myself along with students got special permission to come in once a week and take measurements so that we could design this meridian line," explained Baker. "And when we took measurements, it was a concrete floor and there was all kinds of construction going on. We only had two months of measurements, so we had to put that information into a model that we built to predict where it would hit the rest of the year."


All that measuring and modeling created a bit of drama Thursday afternoon, as a crowd of students, administrators and professors gathered just before 1:30 p.m. to see how the gnomon would perform on its first Vernal Equinox. As emcee, Baker walked the crowd through a brief history of the project and took questions ranging from hyper-technical to, "Why is the sun symbol a square?" (Baker’s chuckling answer, after a pause: "I can offer no insight into that.") If all went according to plan, Baker explained, the sun would pass through a Macedonian solar glyph emblazoned on the atrium tile at exactly 1:33:47 p.m. CDT.


"It’s going to be 8 millimeters off, which is important to some of us," said Baker to laughs from the onlookers. "We have recreated (Danti’s error) in our building as well; this meridian line in the building is supposed to be aligned true north-south, but it turns out it’s not nine degrees off, but it’s 1.8 degrees off."


Not that anyone in the crowd would have noticed, if not for the self-flagellation. As the students cheered and applauded as the sun hit its mark right on cue, Baker raised his eyes to the gnomon hole high above, his mouth agape with geeky glee.


"To my knowledge, there’s nothing like this in an academic setting anywhere in the world," said Salisbury. "It really is quite unique."