ASTRO-110 Lecture Notes - Lecture 30: Hebrew Calendar, Lunar Phase, September Equinox
22 Sep 2020
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Document Summary
Reasons for seasons the tilt of earths axis causes sunlight to fall differently on earth at different times of the year. Both hemispheres are laminated equally during march and september. June solstice: summer solstice northern hemisphere is tilted most directly to the sun. December solstice: winter solstice northern hemisphere receives the least sunlight. March equinox: spring equinox northern hemisphere is tipped slightly toward the sun. September equinox: fall equinox northern hemisphere first starts to be tipped away from the sun. True length of a year is 365 days. Precession: gradual wobble that alters the orientation of earths axis in space. Doesn"t change the amount of axis tilt, just the points in earths orbit at which the solstices and equinoxes occur. Every 29 days the moon goes through its lunar phases. Half the moon always faces the sun. Phase is related to the time it rises, reaches its highest point, and the time it sets.
