Moon Phases

Moon Phases The apparent shape of the Moon in our sky depends

on how much of the Moon’s illuminated side is visible from Earth.

Phases are seen, because only part of the illuminated side of the Moon is visible from Earth, and the part of the Moon that is in its own shadow cannot be seen.

As Earth orbits the Sun, the Moon orbits the Earth. As a result, the Moon has to travel a little more than one complete orbit around Earth to realign itself with the Sun and Earth to get to a particular phase.

New Moon and Full MoonWhen the Moon passes between the Sun and

Earth, none of the illuminated side of the Moon is visible and only the non-illuminated side faces Earth. This called a “new moon”.

When the Earth is between the Moon and the Sun, the entire illuminated side is visible from Earth. It is called a “full moon”.

Waxing and Waning During the waxing phases, the illuminated

portion of the Moon is continually growing (waxing) Right side of the moon is getting bigger

During the waning phases, the illuminated portion of the Moon is continually shrinking (waning)

Right side of the moon is getting smaller

What else?The moon is visible during the day, because it reflects

the Sun’s light.

Earth’s rotation causes the Moon to rise and set like the Sun.

Each phase of the Moon last a little over half a week.

During a 24-hour period, everyone on Earth will see essentially the same phase of the Moon, since the Moon moves only a short distance in its orbit relative to Earth as Earth makes one complete rotation on its axis.