2005/01/14 | 历书秒[Ephemeris Second]
类别(¤〖天文〗) | 评论(0) | 阅读(20) | 发表于 12:38
31,556,925.974 ephemeris seconds are defined as the length of the tropical year 1900.0. This differs from the SI second, which is defined in terms of vibration of a Cs atom.
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