New Moon: Why the Moon Seems to Vanish and Why a New Moon Is Not a Solar Eclipse
At new Moon the Moon is in the same part of the sky as the Sun, and the side facing Earth is dark. That is why you cannot see it, and why it usually brings no eclipse.
Also called
No other names found in our sources.
A simplified model
The drawings are computed from the numbers in the sources. They simplify the real sky. For exact times and dates, use official tables.
Once a month, the Moon seems to vanish from the sky. It has not gone anywhere. It is still circling Earth, but the side that faces us is dark. Astronomers call this moment the new Moon, and it marks the start of the 29.5-day cycle of phases.
This guide explains what a new Moon is, why it is invisible, where it sits in the cycle and why it does not cause a solar eclipse every month. It also clears up a name that has two meanings. At the end you can try it yourself in the Moon Dial.
What a new Moon is
The Moon makes no light of its own. NASA says moonlight is sunlight reflected off the Moon's surface, and the Sun always lights half of the Moon. What changes through the month is how much of that lit half is turned toward us.
At new Moon the lit half faces away from Earth. NASA calls it the invisible phase of the Moon, with the illuminated side facing the Sun and the night side facing Earth. The U.S. Naval Observatory defines it the same way in its list of the eight phases: the Moon's unilluminated side faces the Earth, and the Moon is not visible, except during a solar eclipse.
Seen from the Moon, the picture flips. NASA says that when the far side is fully lit and the near side is dark, we call it a new Moon. So the far side, which many people call the dark side, is in full sunshine at this moment. NASA says there is no permanent dark side: the far side gets as much sunlight as the near side.
Two meanings of new Moon
The name is used in two ways, and both are common.
The first is the astronomical definition. Astronomers pin the new Moon to an exact instant. The Naval Observatory says it happens when the Moon's ecliptic longitude equals the Sun's, a difference of 0 degrees. The ecliptic is the plane of Earth's orbit around the Sun, so this means the Moon and the Sun sit at the same position along that path, as seen from Earth. NASA's Scientific Visualization Studio gives the same modern definition and adds that the part of the Moon facing us is completely in shadow then. Almanacs and calendars publish the date and time of this instant.
The second is the traditional new Moon. NASA's visualization team describes it as the earliest visible waxing crescent. Many lunar and lunisolar calendars use it to mark the start of a month. The Naval Observatory says the same about the Islamic calendar: the first time the thin crescent shows, low in the evening sky just after sunset, marks the beginning of a month.
When a guide, a calendar or a quiz says new Moon, check which meaning it uses. On this site, and in the Moon Dial, the new Moon is the astronomical one: the dark Moon.
Where it sits in the cycle
Both NASA and the Naval Observatory give the length of the cycle as about 29.5 days. The Naval Observatory calls the days counted from the new Moon the Moon's age, so a new Moon has an age of 0. It calls one full cycle of phases a lunation. A new Moon ends one lunation and starts the next.
In the drawing, sunlight comes from the right and the Moon sits on the right side of its orbit, between Earth and the Sun. Its lit half faces the Sun, so the half facing Earth is dark. The Naval Observatory puts it simply: a new Moon occurs when the Sun and Moon are quite close together in the sky.
The new Moon is the first of four primary phases, along with first quarter, full Moon and last quarter. Almanacs publish the dates and times of these four. The crescent and gibbous phases in between are intermediate phases, and each lasts about a week.
The Moon needs about 27.3 days to complete one orbit, yet NASA says it takes about 29.5 days to go from one new Moon to the next. The reason is that Earth and the Moon also move around the Sun. After one orbit, sunlight reaches the Moon at a slightly different angle, and it takes a little more than two extra days for the lighting to match the starting point again.
Why you cannot see it
Two things hide the new Moon. First, the lit side faces away from us. The Naval Observatory says the percent of the disk that is illuminated is 0 at new Moon, 50 at the quarters and 100 at full Moon. Second, the Moon is in the same part of the sky as the Sun. NASA says it rises and sets with the Sun, so it is up during the day, but it is not visible in the daytime sky because its unlit side faces Earth.
NASA also notes that the Moon is up as much during the day as at night, but you may not notice it because the Sun is up too. At new Moon there is no bright side to notice at all. The table compares the new Moon with its opposite, the full Moon.
| Compare | New Moon | Full Moon |
|---|---|---|
| Moon and Sun in the sky | Close together | Nearly opposite |
| Which side of the Moon is lit | The side facing away from Earth | The side facing Earth |
| Time of day on the Moon's near side | Night | Day |
| Percent of the disk lit | 0 | 100 |
| Rises and sets | With the Sun | Rises at sunset, sets at sunrise |
A new Moon is not an eclipse
A solar eclipse can happen only at a new Moon, when the Moon is between Earth and the Sun. NASA's education pages say so directly. The reverse is not true. Most new Moons bring no eclipse.
The reason is the tilt of the Moon's orbit. NASA's Moon Fact Sheet lists the inclination of the orbit to the ecliptic as 5.145 degrees, and NASA's other pages round it to about 5 degrees. Because of the tilt, NASA says, the Moon does not usually pass directly between Earth and the Sun. It passes near the Sun from our point of view. NASA's Goddard team describes the result this way: sometimes the Moon's shadow is too high above Earth, sometimes it is too low, and only now and then is it just right. NASA's My NASA Data lesson says the shadow misses Earth at about five out of six new Moons.
So the dark Moon you cannot see is the ordinary case. A solar eclipse is the special case, when the Moon's shadow lands on Earth and the Moon blocks all or part of the Sun's bright face. Our guide on why most new Moons bring no solar eclipse goes deeper into the geometry.
Eclipses call for care. NASA's eclipse safety page says it is not safe to look directly at the Sun without specialized eye protection for solar viewing, except during the brief total phase of a total solar eclipse. During partial or annular eclipses it is never safe without proper eye protection, and regular sunglasses, no matter how dark, are not enough. Read our guide to watching eclipses safely and NASA's Eclipse Viewing Safety page, listed in the sources below, before you plan to watch one.
Common mistakes
- Looking for the new Moon at night. It rises and sets with the Sun, so it is not in the night sky. Its dark side faces Earth, so you cannot see it by day either.
- Calling the far side the dark side. At new Moon the far side is in full sunlight. NASA says there is no permanent dark side.
- Blaming Earth's shadow. NASA says Earth's shadow touches the Moon only during a lunar eclipse. The phases come from our changing view of the lit half.
- Expecting an eclipse at every new Moon. The Moon's orbit is tilted by about 5 degrees, so the shadow misses Earth at most new Moons.
- Mixing up the two meanings. The astronomical new Moon is dark. The traditional new Moon, used by many calendars, is the first thin crescent.
- Searching for it near the Sun. The new Moon sits close to the Sun in the sky. Never look toward the Sun to find it. NASA says it is not safe to look directly at the Sun without specialized eye protection.
Try it in the instrument
Open the Moon Dial and set the sky to a New Moon. The target is an age of about 0 days. The cycle repeats every 29.5 days, so the scale starts over at that point, and an age just under 29.5 days is also a new Moon. The dial reads about a day on either side of the exact moment as New Moon.
Turn the pointer until the Moon sits on the Sun's side of Earth, between Earth and the Sun. The disk under Seen from Earth should be dark, with no lit edge, because the lit half faces away from us. On Bronze the dial prints the phase names. On Silver you only get tick marks. On Gold you get no marks, so you have to match the picture of a Moon with nothing lit. The request names no place, so the default Northern Hemisphere view works.
Questions people ask
Is a new Moon the same as no Moon?
No. The Moon is still there. At new Moon it sits near the Sun in the sky and rises and sets with it, but the side facing Earth is unlit, so we cannot see it. NASA and the Naval Observatory describe it this way.
How many days pass from one new Moon to the next?
About 29.5 days. NASA says the Moon needs about 27.3 days to orbit Earth, but about 29.5 days to go from new Moon to new Moon, because Earth and the Moon also move around the Sun.
Why is there no solar eclipse at every new Moon?
The Moon's orbit is tilted about 5 degrees, so at most new Moons the Moon's shadow passes above or below Earth. NASA's lesson says it misses at about five out of six new Moons. Watching an eclipse safely takes special eye protection, as NASA's safety page explains.
Is the new Moon the day the first crescent appears?
Not by the astronomical definition, which is an exact instant when the Moon is dark. The traditional new Moon is the earliest visible crescent, and NASA's visualization team says many lunar and lunisolar calendars use it to start a month. The Naval Observatory says the same about the Islamic calendar.
Sources
- Moon Phases, NASA Science. https://science.nasa.gov/moon/moon-phases/. Opened November 9, 2026.
- Phases of the Moon and Percent of the Moon Illuminated, U.S. Naval Observatory, Astronomical Applications Department. https://aa.usno.navy.mil/faq/moon_phases. Opened November 9, 2026.
- Top Moon Questions, NASA Science. https://science.nasa.gov/moon/top-moon-questions/. Opened November 9, 2026.
- Moon Phase and Libration, 2026, NASA Scientific Visualization Studio. https://svs.gsfc.nasa.gov/5587/. Opened November 9, 2026.
- Moon Fact Sheet, NASA Space Science Data Coordinated Archive. https://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html. Opened November 9, 2026.
- Why Don't We Have a Solar Eclipse Every Month?, NASA Science (NASA Goddard Space Flight Center video). https://science.nasa.gov/resource/why-dont-we-have-a-solar-eclipse-every-month/. Opened November 9, 2026.
- Why Don't We Have Solar Eclipses Every Month?, My NASA Data (NASA lesson plan, supported by NASA HEAT). https://mynasadata.larc.nasa.gov/lesson-plans/why-dont-we-have-solar-eclipses-every-month. Opened November 9, 2026.
- Eclipse Viewing Safety, NASA Science. https://science.nasa.gov/eclipses/safety/. Opened November 9, 2026.
We opened each source ourselves on the date shown. The drawings are our own and were checked against the numbers in these sources.
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