فيديو من Dmitry Petrov

As the moon rotates around the earth it travels through phases. The alignment of the sun, earth, and moon create the phases. I use an orrery to explain the moon’s alignment during, new moon, waxing crescent, ist quarter, waxing gibbous, full moon, waning gibbous, last quarter, waning crescent, and back to new moon. The sidereal period is 27.3 and the moon is measured against stars. The synodic period is 29.5 days and the moon is measured against the sun. You may also enjoy Rotation and Revolution of the Earth with an Orrery