A new moon occurs when the sun, moon, and Earth are aligned and the moon is between the sun and Earth in its orbit.
First phase of the lunar cycle
There are a total of eight phases of the moon in a lunar cycle. In order, these are new moon, waxing crescent moon, first quarter moon, waxing gibbous moon, full moon, waning gibbous moon, third quarter moon, and waning crescent moon.
Since a lunar cycle begins with a new moon, it is the first phase of the lunar cycle.
The meaning of a new moon
The moon is called “new” because it marks the beginning of a “new” lunar month. In ancient times, when there was no calendar, the moon was used to measure the length of a month.
A lunar month is the duration from one new moon to the next new moon. The average length of a lunar month is equal to 29.531 days.
Notice, the length of a lunar month is slightly shorter than a calendar month (except for February).
The invisible phase of the moon
A new moon is the invisible phase of the moon.
During a new moon, the moon is in front of the sun with respect to Earth. So the side of the moon that faces our Earth is in complete darkness, or 0% illuminated. That’s why a new moon is invisible to us.
A new moon is only visible during a solar eclipse.
Rise and set time of a new moon
A new moon rises around sunrise, reaches its highest point in the sky (overhead point) around noon, and sets around sunset.
A new moon rises and sets with the sun because it is located on the same side of Earth as the sun.
The duration of a new moon
A new moon has no duration as it occurs at a specific moment in time. It is the moment when the moon passes between the sun and Earth in its orbit.
Occurs once every 29.531 days
A new moon occurs once every 29.531 days because the moon takes 29.531 days to complete one orbit around Earth with respect to the sun. This is called a synodic month.
A Black Moon is a new moon
Since a new moon occurs once every 29.531 days, it is possible to fit two new moons into a calendar month.
When two new moons occur in a calendar month, then the second new moon of that month is called a Black Moon.
For that to happen, the first new moon must be on the 1st or 2nd of a calendar month so that the second new moon is on the 30th or 31st.
No solar eclipse at every new moon
A solar eclipse occurs when the moon is in a straight line between the sun and Earth, and the moon’s shadow falls on Earth.
A solar eclipse doesn’t occur at every new moon because the lunar orbit around Earth is tilted 5° with respect to Earth’s orbit around the sun. As a result, the moon’s shadow usually passes above or below Earth.
Read about all eight phases of the moon:
New moon
Waxing crescent moon
First quarter moon
Waxing gibbous moon
Full moon
Waning gibbous moon
Third quarter moon
Waning crescent moon
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