Using the Julian calendar, the spring and fallequinoxes and the seasons were arriving 11 minutes earlier each year. By 1500 the vernal equinox had fallen back to March 11.
根据罗马儒略历，春分、秋分以及四季每年提前11分钟出现，1500年后则提前至3月11日。
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Shadows at the fall and spring equinoxes are said to look like a snake crawling down the steps, similar to the carved serpent at the top.