The Moon is our planet’s only natural satellite. It gives us light during the night when the Sun is shining on the other side of the globe. Some planets have more than 50 moons, like Saturn which has 82. Mercury and Venus, on the other hand, have none.
The Sun is the only object in our solar system that produces light. It lights up everything, including our planet and its moon. Since everything in space moves, the Sun, Moon, and Earth are involved in a celestial dance.
The Earth’s orbit takes it around the Sun and, at the same time, the Moon orbits the Earth. The movement of these three bodies makes day and night. This dance is also responsible for what we call the lunar phase or the phases of the Moon.
The Eight Phases of the Moon
The Moon is tidally locked to Earth. An object is tidally locked when its orbital and rotational periods are the same. It circles the Earth every 27.3 days Which is also the same time it takes to rotate on its axis.
As a result, we always see the same side of the Moon facing our planet. One part of the Moon is always illuminated by the Sun, while the other is not.
We see this illuminated part from different angles depending on the Moon’s position around the Earth. These differences in appearance are what we call Moon Phases. It takes 29.53 for the Moon to complete one complete cycle of these phases. We call this a synodic month.
The 8 phases of the Moon are:
| Moon Phase | What It Means |
|---|---|
| 🌑New Moon | The Moon is invisible from our point of view because the unlit part is facing the Earth. |
| 🌒Waxing Crescent | We can see the first sliver of the Moon as the illuminated portion starts to grow bigger. |
| 🌓First Quarter | Half of the Moon is illuminated as it is already a quarter in its journey around Earth. |
| 🌔Waxing Gibbous | The illuminated part of the Moon is greater than its dark side. |
| 🌕Full Moon | We can see the Moon’s disk fully as the day sight faces Earth, while the Sun is on the opposite side. |
| 🌖Waning Gibbous | The night side of the Moon starts to creep as it continues on its journey around Earth. |
| 🌗Last Quarter | We can see the day and night sides of the Moon in equal parts. |
| 🌘Waning Crescent | The night side takes over the illuminated portion, which gives way to the New Moon phase and a new cycle begins. |
There are four major phases of the Moon: new moon, first quarter, full moon, and last quarter. In these phases, the moon looks 0%, 50%, 100%, and 50% illuminated, respectively. The last quarter is also called the third quarter or the final quarter, a phase when we can see only half of the moon.
The intermediate phases between them are the waxing moon and waning moon phases. “Waxing” means the illuminated part is increasing, while “waning” means the lit part is decreasing.
What is a New Moon?
A new moon is one of eight phases of the lunar cycle. It is when the moon appears the darkest as seen on Earth.
It happens when the Moon is between the Earth and the Sun. The bright side of the Moon is facing the Sun at this time. And in turn, what we see here on Earth is the night side of the Moon.
In the New Moon phase, the Moon and the Sun are in the same part of our sky. That means the moonrise and moonset come along with sunrise and sunset. It is highest around noontime.
We can see the Moon during this time but not as much because it is overpowered by sunlight. At night, it would seem like the Moon has disappeared because we cannot see it lighting up our sky!
It is for this reason that we call the New Moon the invisible phase. Though we cannot see it during this time, just remember that the Moon is always there. Its actual shape does not change too. It just seems to “change shape” as seen on Earth because the lit part increases and decreases as it moves around our planet.
The interesting phenomenon of solar eclipse happens during the new moon. It happens when the Moon is between the Sun and the Earth. However, we do not get solar eclipses every New Moon.
When Does a New Moon Occur?
A new moon is the first phase of the lunar cycle. It occurs when the Moon is between the Sun and Earth. The bright side of the Moon is away from us and the shadowed hemisphere is facing Earth instead.
We can think of the new moon as the opposite of the full moon. In terms of the visible part, we see 100% of the lunar disk during the full moon. However, on a new moon, it becomes totally dark to about 0%. We cannot see it with the naked eye but we know that it is there.
The Black Moon
Most of the time, we get only one new moon in a month. However, our calendars and the moon phases do not exactly coincide.
The common calendar that we are commonly using is the Gregorian calendar. It has 12 months that are usually 30 to 31 days long. The second month, February, has 28 days which becomes 29 every four years on a leap year.
The Gregorian calendar is a solar calendar and it is not based on the movement of the Moon. Moon-based calendars are called lunar calendars. The Moon takes 29.5 days to complete a cycle, which equals one lunar month.
As you see, there is a slight difference between our calendar and the Moon’s cycle. Because of that, there will be rare instances when we get a second new moon. We call it a black moon!
When two new moons occur in a month, we can wait for them around the beginning and the end part of the month. However, seeing these black moons will also depend on your location and differences in time zones/ local time.
Solar Calendar vs Lunar Calendar
We get two main kinds of calendars: solar and lunar. These dating systems are based on the phases and positions of the Earth, Moon, and Sun, relative to each other.
Solar Calendars
The one that we are commonly using nowadays is called the Gregorian calendar. It is an example of a solar calendar. This type is based on the seasons or the Earth’s movement around the Sun. A solar year lasts 12 months and is 365.25 days long.
Lunar Calendars
As the name says, lunar calendars are based on the phases of the Moon. Lunar years are also composed of 12 months but they are shorter. A lunar year lasts 354 days, 11 days shorter than a solar year.
Sidereal Month vs Synodic Month
We often hear about the words “sidereal” and “synodic” when talking about the Moon. These are different ways of referring to months, based on the Moon’s orbital period and the time it takes to complete one cycle.
- Sidereal month: the time it takes for the Moon to orbit the Earth (27.3 days)
- Synodic month: the time it takes for the Moon to complete one lunar cycle, that is, from one new moon to the next new moon (29.5 days)
The synodic month is also called the lunar month and is the basis for the lunar calendar. It is longer than a sidereal month. These differences happen because of the changes in the orbital positions of the Earth as it moves around the Sun.
As the Earth moves, the Moon has to keep up with it. The Moon has to make a bit more than 360° to get around it and complete a lunar cycle.
The Metonic Cycle
The lunar and solar calendars do not coincide because they do not have the same number of days. However, there is a special pattern called the Metonic cycle.
The Metonic cycle is a period of 19 solar years which equals 235 lunar months. After this cycle, the Moon’s phases will fall on the same dates again, as they were 19 years ago.
For example, we had a new moon on November 4, 2021. After 19 years, we will also have a new moon on the same date, on November 4, 2040.
Suitability for Astronomy
If you want to observe the Moon during this phase, then you are out of luck because it is essentially invisible. We get the darkest nights during the new moon phase. However, if you want to see other celestial objects, then it is the best time to go outside for stargazing!
Aside from light pollution, moonlight is one of the big considerations we have to take when stargazing. After all, the Moon is the brightest object in the night sky.
During a full moon, when it is at its brightest phase, fewer objects can be seen in the sky. The Moon’s light easily makes the other celestial objects invisible. Usually, only the brightest objects like Venus, Jupiter, and Mars remain, among others. So if we want to spot other dimmer objects, a dark sky is our best chance.
On a new moon, we are most likely to see the most stars and other astronomical bodies. So, it is the best time to set up camp and prepare our telescopes. We can also see more even with just the unaided eye.
Deep-sky objects like galaxies, nebulae, star clusters, or even meteor showers shine brighter this time because they are not overpowered by the Moon’s light.
If you cannot get a chance during a new moon, the nights before and after it also offer a great stargazing opportunity!
Effect on Tides—Spring Tides
On a new moon (and a full moon), the Sun and Moon form a straight line with Earth. This formation causes the biggest difference in tides called spring tides. Sometimes, these are also called king tides.
Spring tides are not in any way related to seasons. “Spring” here means “jump” or “leap” because the tides seem to leapChinese during this time. On a new and full moon, high tides are at their maximum while the low tides are also very low.
Since the Moon and Sun form a line on a new moon, their gravitational forces combine and have a stronger pull on the tides.
The position of the Moon in its orbit can also cause a big difference in the tides. The Moon follows an elliptical orbit. This oval shape path means that the Moon is sometimes closer (perigee) or farther (apogee) to Earth.
When these three celestial bodies form a line when the Moon is at perigee, we experience even more extreme tides called perigean spring tides. Also, since the Moon is at perigee, it appears larger to us. We call it a supermoon.
Supermoons can happen either on a new moon or full moon, at the Moon’s perigee.
New Moons and Solar Eclipses
Solar eclipses are another exciting event that can happen on a new moon. An eclipse happens when one body is obscured because another body passes between it and the observer.
On a new moon, the Moon aligns with the Sun and Earth. The Moon totally or partially blocks direct sunlight and casts a shadow on Earth. We call this a solar eclipse.
We do not get solar eclipses every time there is a new moon. This is because the Moon’s orbit is tilted by about 1.5 degrees. Sometimes it is above the Earth’s plane and sometimes below it. We only experience a solar eclipse when the Moon perfectly aligns with the Sun and Earth.
Another eclipse occurs when the Moon, Earth, and Sun align—a lunar eclipse. It happens during a full moon.
Religious, Cultural, and Historical Significance
The movements of the Sun, Earth, and Moon are important to our daily activities and our lives as a whole. Nocturnal animals come out at night while we, humans, rest during that time.
In astronomy, a new moon means the start of the lunar cycle. In other beliefs and cultures, it also signifies beginnings. Some people believe that a new moon is a good time to set plans and intentions or even start something.
In an astronomical sense, a new moon means 0% visibility of the moon. However, in calendar contexts, the new moon can mean the first sight of the waxing crescent moon. This sliver after the dark moon marks the start of the month in some calendars, like the Islamic calendar for example.
The Hindu calendar system is also based on the phases of the moon. The new moon signals the day called Amavasya. It means new moon or no-moon day. It is a powerful day and many Hindus pray and fast on this day. They also make offerings to their departed loved ones and ancestors during Amavasya.
In Jewish tradition, the new moon marks the first day of the month in the Hebrew calendar. They call it Rosh Chodesh or Rosh Hodesh which translates to “beginning of the month.” Some observances on this minor holiday include additional prayers and service. It is also a holiday celebrated by women when they can enjoy their day and refrain from work.
Similarly, a new moon marks the start of months and years in the Chinese lunisolar calendar. The Chinese new year has a different date every year because they base it on the lunar phase. It happens on the second (or third) new moon after the December solstice.
Interesting New Moon Facts
- In a new moon, the Earth, Moon, and Sun form a straight line. We call this a conjunction or syzygy. Another syzygy happens during a full moon. This time, their formation becomes the Moon, Earth, and Sun.
- A synodic month is also called a lunation. It is the length of time from a new moon phase to the next.
- When a new moon happens at perigee, at its closest point to Earth, it is called a Super New Moon. We call it a Micro New Moon when it is at apogee, or its farthest point from us.
- A second new moon in a month is called a black moon. Sometimes, we can also witness a second full moon in a month—a blue moon!
- There will be times when February will have no New Moon. It occurs once every 19 years or after the Metonic cycle. But why only in February? Because it is the only month shorter than a lunar month.
- Usually, when there is no New Moon in February, the months before and after it will have two New Moons. An example of this event happened in 2014 when January and March had two new moons.
- The Moon lights up our night sky but sometimes the Earth can also reflect light on the Moon. We call it Earthshine. We can best see this dull glow just days before or after a New Moon.
Frequently Asked Questions
How many new moons are there in a month?
We usually get one new moon every month. However, there will be rare occasions when we get two new moons. We call it a black moon.
What is the difference between a new moon and a full moon?
A new moon is when we do not see the Moon at all. On the other hand, a full moon means we see it illuminated 100%. Both of these happen when the Sun, Moon, and Earth form a straight line.
How often does a Black Moon appear?
A black moon generally occurs once every 32 months (2 years and 8 months). This event is sometimes only seen in specific time zones, so it helps to always check for updates!
Sources:
https://www.sumanasinc.com/webcontent/animations/content/sidereal.html
https://www.timeanddate.com/astronomy/moon/black-moon.html
https://www.nationalgeographic.com/science/article/black-moon-explained-phases-earth-sun-space-science
(https://earthsky.org/earth/tides-and-the-pull-of-the-moon-and-sun/)
https://www.almanac.com/astronomy/moon/calendar
https://www.timeanddate.com/astronomy/moon/new-moon.html
https://moon.nasa.gov/moon-in-motion/moon-phases/
https://www.moonglow.com/blogs/shoot-for-the-moon-blog/a-guide-to-the-significance-of-the-new-moon-phase
(https://www.myjewishlearning.com/article/rosh-chodesh-101/)
Image Sources:
The Moon: https://upload.wikimedia.org/wikipedia/commons/thumb/e/e1/FullMoon2010.jpg/800px-FullMoon2010.jpg
Phases of the Moon: https://moon.nasa.gov/internal_resources/359
New Moon: https://moon.nasa.gov/internal_resources/366/
New moon/black moon: https://upload.wikimedia.org/wikipedia/commons/thumb/d/dd/New_Moon.jpg/800px-New_Moon.jpg
calendar: https://www.biblicaltruths.com/wp-content/uploads/2017/12/calendar.jpg
stargazing: https://live.staticflickr.com/5348/17871274242_37b3090cb7_b.jpg
tides: https://live.staticflickr.com/6235/6395132075_b05055a58a_b.jpg
partial solar eclipse: https://theplanets.org/123/2021/11/Partial-solar-eclipse.jpg
chinese new year: https://live.staticflickr.com/2225/2251918567_44b87c9e83_b.jpg