Lunar Cycle Notes

Rotation vs. Revolution

Rotation: Revolution: spin of object on its axis rotates counter-clockwise = west to east = why sun appears to rise in the east and set in the west for Earth = 24 hrs. =1 day responsible for day vs. night Revolution: also called an orbit path of one object around another Earth around sun ≈ 365 days = 1 year moon around Earth ≈ 1 month

Moon vs. Earth The moon revolves with Earth around the Sun as the Moon is revolving around Earth. The moon revolves around Earth in 29½ Earth days. Similarly to Earth, as the moon revolves, it is rotating or spinning on its axis. The rotation time for the moon is a little over 27 Earth days.

Moonlight The same side of the moon always faces Earth because the moon rotates at the same rate that it revolves around the Earth. The moon appears lit at night because it is reflecting sunlight, as is every object in the universe except for stars. The moon does not produce it’s own light.

Full vs. New Moon A full moon occurs when the earth is between the sun and the moon. A new moon occurs when the moon is between the Sun and the Earth.

Moon Phases If the moon appears greater than one-half illuminated, it is known as a gibbous moon. If the moon appears to be less than one-half illuminated, then it is called a crescent moon. If the moon appears to be getting bigger (sunlit portion increases) each night it is said to be waxing. If the moon appears to be getting smaller (sunlit portion decreases) each night then it is said to be waning.

Full moon: all of surface facing Earth is illuminated (= lit) by the Sun New moon: moon is between Earth & Sun, so lit portion is facing away from Earth Waxing moon: lit portion “growing” Waning moon: lit portion “decreasing” Gibbous moon: larger than ½ Crescent moon: smaller than ½

Lunar Cycle

Draw This…as viewed from Earth

Where is the sun in this diagram?