Glossary term: 世界时（UT）
Description: 世界时，缩写为 UT，是定义时间测量的几种方式的总称。UT1是零经度（格林威治皇家天文台的历史所在地）的平太阳时。平太阳时将一天的长度定义为从一个正午（太阳在天空中的最高位置）到下一个正午之间的平均时间。实际上，必要的测量不是通过太阳，而是通过遥远的天体（如夜间的类星体）进行的。UTC，协调世界时，是一种基于一组特定的大型原子钟（“国际原子时”或 TAI）计时的时间标准，但偶尔会在某些日子添加额外的秒数（“闰秒”），以确保 UTC 和 UT1 的偏差不会超过 0.9 秒。
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Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher The translation of this term and its definition is still awaiting approval
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