What is the relationship between lunar phases and the location of the Sun ?
Looking down on the solar system from one of the ecliptic poles, the New Moon occurs when the Moon is roughly between the Sun and the Earth, and the Full Moon when the Earth is between the Sun and the Moon. These do not always lead to solar and lunar eclipses because the plane of the lunar orbit is tilted about 5 degrees to the ecliptic plane or 10 times the lunar or solar diameter. Most of the time the Moon passes above or below the position of the Sun and the Earth’s shadow cone in space. The first and last quarter Moons ( half moons) occur when the Moon is at 90 degrees to the line between the center of the Sun and Earth.
