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月蚀[Lunar Eclipse] [2005-9-3]
iamet 发表在 ¤〖天文〗
| An occultation of the Moon by the Earth's shadow. There are 150 lunar eclipses per century. Lunar eclipses can occur only at full moon, and can be either total or partial. Total lunar eclipses can last up to 2 hours, while partial lunar eclipses can last up to 4 hours.
Full Moons occur on Julian days
where n is a half-integer. Lunar Eclipses occur when n (mod 223) is one of 0.5, 6.5, 12.5, 23.5, 35.5, 41.5, 47.5, 53.5, 76.5, 82.5, 88.5, 94.5, 100.5, 123.5, 129.5, 135.5, 141.5, 158.5, 164.5, 170.5, 176.5, 182.5, 188.5, 205.5, 211.5, or 217.5.
The sequence of eclipses repeats with a period of 223 synodic months, known as the Saros cycle. This period is 18 years, 11 days, and 8 hours if the 18 years include four leap years (or 18 years, 10 days, and 8 hours if the 18 years include five leap years).
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