ASTR 001 Lecture Notes - Lecture 4: Lunar Eclipse, Lunar Phase, Orbital Period
15 Jul 2020
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Document Summary
The moon takes 27. 3 days to orbit once with respect to the stars (sidereal period) Lunar phases repeat every 29. 5 days (synodic period- in respects to the sun) The moon"s rotational period equals its sidereal period. Throughout history, humans have made calendars based on the seasons (with respect to the sun) or the moon"s cycle of phases. The number of calendar days (365) does not fit neatly into months (29. 5) or years (365. 24 days) Lunar eclipse is every 4 years (february has 29 days) Humans creatively made calendars to deal with this. Today the gregorian calendar, which includes leap years to keep it on track, is used. Moon passes between earth and the sun. Only a small portion of the earth can witness each one. Total: the moon completely blocks the sun"s light. Annular: the sun appears as a bright ring surrounding the moon.
