Haagensen Erling, Lind Niels C
Isis. 2015 Dec;106(4):825-34. doi: 10.1086/684766.
There is a unique cluster of four medieval round churches, linked by a simple geometry, on Bornholm Island in the Baltic Sea. Why so many and why so close together? Immediate simple answers are "Just by chance" and "For no reason." Why are the churches round? "Defense." This essay proposes another hypothesis for this unique situation: the churches are astronomical observatories, meant to solve a scientific problem (Is the Earth really spherical?) and a practical problem (How far is it to sail west to the Orient?). The capacity and desire to find answers, together with other practical needs related to astronomy, can better explain these round churches' special architecture. The geometry that connects them fits the ideal pattern with an angular accuracy of 1 minute of a degree. The round churches may be the earliest astronomical observatories in Christian Europe; other hypotheses have been shown to be untenable. Their location provides for a good method to estimate the Earth's extent in the east-west direction, seemingly the earliest such measurements.
在波罗的海的博恩霍尔姆岛上，有一组独特的四座中世纪圆形教堂，它们由一种简单的几何形状连接在一起。为什么有这么多教堂，而且彼此靠得这么近？直接的简单答案是“纯属偶然”和“毫无缘由”。为什么教堂是圆形的？“为了防御”。本文针对这种独特情况提出了另一种假说：这些教堂是天文台，旨在解决一个科学问题（地球真的是球形吗？）和一个实际问题（向西航行到东方有多远？）。寻找答案的能力和愿望，以及与天文学相关的其他实际需求，能够更好地解释这些圆形教堂独特的建筑风格。连接它们的几何形状符合理想模式，角度精度达到1分。这些圆形教堂可能是基督教欧洲最早的天文台；其他假说已被证明站不住脚。它们的位置提供了一种估算地球东西方向范围的好方法，似乎是此类测量的最早实例。
