Urban Adventure in Rotterdam: Urban archeo-astronomy

Sunday, May 25, 2014

Urban archeo-astronomy

I have favorite coffee-drinking and reading spots in Rotterdam. One of them is the LaPlace cafeteria above the V&D department store. I still remember reading Gravity's Rainbow here, with apple-pie, one Saturday afternoon. But I didn't expect to witness an urban variation of the Martinsloch phenomenon.

28 december 2013 - 13:49:38

sun position Elevation Azimuth latitude longitude

28/12/2013 13:48 | GMT1 13.52° 195.16° 51.9° N 4.4° E

I knew about the Martinsloch phenomenon from books about archeo-astronomy:

The St. Martin's hole is a rock window above the Swiss village of Elm. On two days in spring and summer the sun shines through the St. Martin's Hole directly onto the Church of Elm.

On good weather days the church is illuminated for about 2.5 minutes, then the bright spot has moves away from the church. In fog or haze a clearly visible ray of sunlight, five kilometers long, can be seen, before and after the ray hits the church.

Both occultists and astronomers are fond of making a pilgrimage to Elm on March 12 and 13, and on September 30 and October 1. The moon is also visible through the Martin's Hole at less regular times.

28 december 2013 - 13:50:34

A common source of data for archaeoastronomy is the study of alignments. This is based on the assumption that the axis of alignment of an archaeological site is meaningfully oriented towards an astronomical target.

In Rotterdam the sun shines between the towers of the Schielandtoren and the Robeco-bank. This produces a well defined and short-lasting sunbeam that quickly passes through the LaPlace cafeteria. The path can be traced on the nice website of Sun-Earth tools.

No one seemed to notice the spectacular phenomenon they were witnessing. Everyone kept talking, eating and drinking. No one seemed to grasp what I was photographing so excitedly. It was just the sun shining as always.