Picture the movement of the moon in terms of a clock whose hands are moving backward. The moon rests on the clock’s hour hand, Earth sits at the clock’s center, while the sun shines far off in the direction of 12 o'clock. As the moon orbits counterclockwise around Earth, its position relative to the sun and Earth changes, giving us the varied phases of the moon. Each phase of the moon lasts approximately 5 days.
The New Moon:
The first phase in the lunar cycle is the new moon. The moon is positioned between the sun and Earth at 12 o'clock. From Earth, the sun and moon appear to be in the same part of the sky and will rise and set together. The side of the moon that receives the sun’s light is facing away from Earth, so no moon is visible to us on Earth’s surface. On a very clear night, you might be able to make out a faint gray outlined view of the moon. This comes from the light of the sun being refracted off the Earth and back out to the moon.
One day after the new moon, a faint sliver outline can be seen low on the western horizon at sunset. The moon has moved from new to a waxing crescent phase. As the moon continues in its counterclockwise orbit, the crescent grows larger, or waxes. One week later, the moon reaches its second primary phase, the first quarter moon. Accordingly, the moon has moved one quarter of the way around Earth.
The First Quarter:
At the first quarter, the moon sits at 9 o'clock. The sun, Earth, and moon form a right triangle on the left side of the clock. Here only half of the moon’s disk is illuminated. At first quarter, the moon rises 6 hours after the sun – at about noon. It reaches its highest point at sundown and sets around midnight. That means the moon can be seen during daylight hours in the afternoon.
For several days after first quarter, the moon continues to wax but it is in a waxing gibbous phase instead of a waxing crescent. A gibbous moon is more than a quarter moon but less than a full moon. During this phase, the moon moves from 9 o'clock to 6 o'clock on the dial, and the sun-Earth-moon angle is getting larger – just like the moon’s phase.
The Full Moon:
When the moon reaches its 6 o'clock position, the phase is full. The side of the moon that faces Earth is fully illuminated – that large circle of light a certain two-year-old child (my son) called the moon ball. On the clock, the sun, Earth, and moon form a straight line. From Earth, the sun and moon appear to be at opposite ends of the sky. So as the sun sets, the moon rises. The full moon is now visible all night.
Once it’s past full, the moon moves from 6 o'clock to 3 o'clock and the sun-Earth-moon angle begins to shrink. The moon’s phase is also getting smaller. It’s moving from waning gibbous to its third- or last-quarter phase.
The Last Quarter Moon:
This third-quarter moon sits at 3 o'clock on the phase dial, where the sun-Earth-moon angle is once again 90°, but this time it’s on the right side of the clock. From Earth, we see half of the moon’s disk illuminated – the side opposite as the one illuminated at first quarter. A third-quarter moon rises about six hours after the sun sets, reaches its highest point in the southern sky at dawn, and sets at about noon.
As the moon orbits Earth (the inner circle) its position relative to the sun and Earth changes. This causes the lunar phases we see in our sky (the outer circle). In the week after the third quarter, the moon moves through its waning crescent phase to it’s dark phase.
The Dark Moon:
About 3 to 5 days before the eventual return to the new moon phase, where the cycle begins again, the moon enters a dark phase. The moon sits at about 2:30 on the dial. Here the moon is neither illuminated by the sun (in a crescent phase), nor is it able to reflect the light of the sun providing an outline of it’s surface (as in the new moon phase). It is truly dark and seemingly has disappeared from the sky.
The New Moon:
The first phase in the lunar cycle is the new moon. The moon is positioned between the sun and Earth at 12 o'clock. From Earth, the sun and moon appear to be in the same part of the sky and will rise and set together. The side of the moon that receives the sun’s light is facing away from Earth, so no moon is visible to us on Earth’s surface. On a very clear night, you might be able to make out a faint gray outlined view of the moon. This comes from the light of the sun being refracted off the Earth and back out to the moon.
One day after the new moon, a faint sliver outline can be seen low on the western horizon at sunset. The moon has moved from new to a waxing crescent phase. As the moon continues in its counterclockwise orbit, the crescent grows larger, or waxes. One week later, the moon reaches its second primary phase, the first quarter moon. Accordingly, the moon has moved one quarter of the way around Earth.
The First Quarter:
At the first quarter, the moon sits at 9 o'clock. The sun, Earth, and moon form a right triangle on the left side of the clock. Here only half of the moon’s disk is illuminated. At first quarter, the moon rises 6 hours after the sun – at about noon. It reaches its highest point at sundown and sets around midnight. That means the moon can be seen during daylight hours in the afternoon.
For several days after first quarter, the moon continues to wax but it is in a waxing gibbous phase instead of a waxing crescent. A gibbous moon is more than a quarter moon but less than a full moon. During this phase, the moon moves from 9 o'clock to 6 o'clock on the dial, and the sun-Earth-moon angle is getting larger – just like the moon’s phase.
The Full Moon:
When the moon reaches its 6 o'clock position, the phase is full. The side of the moon that faces Earth is fully illuminated – that large circle of light a certain two-year-old child (my son) called the moon ball. On the clock, the sun, Earth, and moon form a straight line. From Earth, the sun and moon appear to be at opposite ends of the sky. So as the sun sets, the moon rises. The full moon is now visible all night.
Once it’s past full, the moon moves from 6 o'clock to 3 o'clock and the sun-Earth-moon angle begins to shrink. The moon’s phase is also getting smaller. It’s moving from waning gibbous to its third- or last-quarter phase.
The Last Quarter Moon:
This third-quarter moon sits at 3 o'clock on the phase dial, where the sun-Earth-moon angle is once again 90°, but this time it’s on the right side of the clock. From Earth, we see half of the moon’s disk illuminated – the side opposite as the one illuminated at first quarter. A third-quarter moon rises about six hours after the sun sets, reaches its highest point in the southern sky at dawn, and sets at about noon.
As the moon orbits Earth (the inner circle) its position relative to the sun and Earth changes. This causes the lunar phases we see in our sky (the outer circle). In the week after the third quarter, the moon moves through its waning crescent phase to it’s dark phase.
The Dark Moon:
About 3 to 5 days before the eventual return to the new moon phase, where the cycle begins again, the moon enters a dark phase. The moon sits at about 2:30 on the dial. Here the moon is neither illuminated by the sun (in a crescent phase), nor is it able to reflect the light of the sun providing an outline of it’s surface (as in the new moon phase). It is truly dark and seemingly has disappeared from the sky.
