Monday, September 19, 2011

Catholic Time

A couple of days ago I posted about making quick handouts for my Catechism class. One of them included this image of St. Michael's Church (Michaeliskirche) in Hildesheim (Hilda's Home, a Saxon goddess), Germany:

I was tempted then to say something about the pattern of the snow in the shaded foreground, but it wasn't relevant to the subject of catechetical handouts. But I'll say something about it today since it points to something important about Catholicism.

Germany sits higher on Earth's globe than America does (excepting Alaska). Hildesheim lies at the 52nd parallel, further north than Winnipeg, Manitoba. So at the winter solstice, the sun doesn't get very high, and even at noon will cast long shadows. Looking at the shadow in the foreground, you can see that beyond the shadow there's almost no snow.

So I was looking at the snow and thinking that the building behind the photographer lay on an east-west axis. And because the edge of the shadow is parallel to the church, then the church lies on an east-west axis as well. Of course this makes sense: Catholic churches are traditionally "oriented" to face the rising sun. And if the east-west orientation is correct, the shadow of the leftmost tower tells us it's a bit before noon, on a day near December 21.

Idly curious about just how well-aligned the church was to true East, I had a look on Google Earth:

That's odd: the church is oriented a bit North of true East. Maybe it was oriented to align with where the sun would rise on St. Michael's feastday...that'd be September 29. The answer is no, because after the Sept 21 Equinox, the sun will rise and set in the South; look at Hildesheim's solar chart for Sept 29:

The yellow line shows the sun rising about 3 degrees South of 90 East, not North. But wait a sec, Europe used the less-accurate Julian calendar when construction of St. Michael's began in AD 1001. When the Church replaced the Julian calendar with the Gregorian in 1582, there was a 10-day error between the sun and the calendar. In 1001, there was a 6-day error. To get the proper solar chart for Sep 29, 1001, we have to subtract 6 days, which gives us Sept 23. But that date still has the sun rise a couple of degrees south of East.

Huh...suppose instead of using the saint's feastday, we go with Sept 21, the Equinox? Maybe the builders fully intended to lay the church out at 90 degrees East by measuring at dawn on September 21. Yes, but we already know that wouldn't get them true East; but maybe they didn't know. If we subtract 6 days to correct the Julian error, we have Hildesheim's chart for Sept 15:

    That's more like it. The sun rises about 4.5 degrees North of East, and sets about 4.5 degrees North of West. By the way, the sunset & sunrise are figured from the top edge of the sun. The software also accounts for where Hildesheim lies within its time zone: you can see how the yellow 12 representing clock noon doesn't quite match the sun's noon, which is always 180d South. But no-one knows at what instant after the sun broke the local horizon on Sept 21, AD 1001 (Julian calendar) the authorities might have marked the church's axis. And the sun itself is over half a degree wide, so anything between a 4 and 5 degree northward skew on the church's alignment would be extremely accurate.

I inserted the above enlarged image into an Autocad drawing and measured the angle of skew: despite the fuzziness, I get 4 degrees. How about that.

So what does this have to do with Catholicism? Well, consider that in Genesis God saw that all he created was good. And that even after the Fall, God used his physical creation to show his promise to Noah (the Rainbow); to show the Israelites when to break camp (the Shekhinah cloud); and to show the Magi where Jesus was born (the star). So the Catholic Church still stays in touch with God through his creation, and vice versa. We have churches "oriented" to the East, or a saint's feastday dawn; a holiday whose date is calculated each year based on the movement of the Moon and the Sun (Easter); and another which was probably originally observed on the Winter Solstice (Christmas). Given the intimate relationship the Church maintains with God through the physical world, it's no surprise that it was she who recognized the 1-day-per-128-years error in the Julian calendar, and had the knowledge and the authority to fix it.