AST-1002 Lecture Notes - Lecture 2: Lunar Eclipse, Gregorian Calendar, Augustus
Document Summary
Moon"s revolution around the earth takes 27. 3 days; however, because the earth has moved during this period, the phase cycle takes 29. 5 days. The period of the lunar phases (synodic period) is slightly more than 2 days longer than the moon"s orbital period (sidereal period). Phases of the moon: first quarter looks like a letter p Total solar eclipse happens when the moon is close enough to the earth, so that the dark part of the moon"s shadow (the umbra) reaches out to the earth. annular solar eclipse happens when the moon is not close enough to the earth, so that only the dimmer part of the moon"s shadow (the penumbra) reaches out to the earth. In this case only a part of the sun"s disk is covered, leaving a bright ring (annulus). The dark part of the moon"s shadow covers only a small part of the earth. As a result solar eclipses are not often visible.
