Some nights the moon is a bright silver coin, other nights a thin curl of light, and some nights it seems to vanish altogether. If you've ever wondered why, you're in good company. People have watched the moon change shape for as long as there have been people, and its steady rhythm has shaped calendars, harvests and traditions all over the world.
The good news is that the lunar cycle is easy to understand once you know one simple idea. This guide walks you through why the moon has phases, what each of the eight phases looks like, when to look for them in the sky, and a few gentle ways to follow along at home.
Why does the moon have phases?
The moon doesn't make its own light. It shines because sunlight falls on it, and at any moment the sun lights up half of the moon, the half facing the sun. As the moon travels around Earth, we see different amounts of that sunlit half. When the lit side faces us, we see a full moon. When it faces away, we see almost nothing, and that's the new moon. Everything in between is a slice of the lit half seen from an angle.
A common mix-up is that the phases are caused by Earth's shadow. They aren't. Earth's shadow only falls on the moon during a lunar eclipse, which is a separate and much rarer event.
It takes about 29.5 days to go from one new moon to the next. This is called the synodic month, and it's where our idea of a "month" comes from. The moon actually completes one orbit relative to the stars in about 27.3 days, but because Earth is also moving around the sun during that time, the moon needs a couple of extra days to line up with the sun again.
An easy way to remember: the side of the moon that's lit always points toward the sun. In the evening after sunset, a lit moon in the west is a waxing moon. In the early morning before sunrise, a lit moon in the east is a waning moon.
The eight phases of the moon
Astronomers name four main phases (new moon, first quarter, full moon and third quarter) and four in-between phases. "Waxing" means the lit part is growing, and "waning" means it's shrinking. The descriptions below are as seen from the Northern Hemisphere.
1. New moon
The moon sits roughly between Earth and the sun, so its lit side faces away from us and it's essentially invisible. It rises and sets with the sun and is lost in the daytime glare. A solar eclipse can only happen at new moon, though most new moons pass without one.
2. Waxing crescent
A day or two after new moon, a thin sliver appears low in the western sky just after sunset, lit on the right side. Look closely and you may see the rest of the moon glowing faintly. That soft glow is earthshine, sunlight reflected off Earth onto the moon's dark side.
3. First quarter
About a week after new moon, the moon looks like a half circle, lit on the right. It's called a quarter because the moon is a quarter of the way through its cycle. It rises around midday, sits high in the sky at sunset, and sets around midnight, which makes it a lovely evening moon.
4. Waxing gibbous
More than half lit and growing fuller each night. Gibbous comes from an old word meaning humped, which describes its rounded shape well. You'll find it in the afternoon and evening sky.
5. Full moon
About two weeks after new moon, Earth sits roughly between the sun and the moon, and we see the whole lit face. The full moon rises around sunset and sets around sunrise, so it's up all night. A lunar eclipse can only happen at full moon.
6. Waning gibbous
The lit part begins to shrink, now from the right side. The moon rises later each evening, so a waning gibbous is often easiest to spot late at night or in the morning sky.
7. Third quarter
Also called the last quarter. The moon is a half circle again, but this time lit on the left. It rises around midnight and is high in the sky at sunrise, so early risers often spot it in the blue morning sky.
8. Waning crescent
A thin sliver lit on the left, rising in the east shortly before dawn. Over the next few days it slips closer to the sun until it disappears into the next new moon, and the cycle begins again.
When to look for the moon
On average, the moon rises about 50 minutes later each day. That's why it seems to show up at different times through the month. A quick cheat sheet:
- Waxing crescent: western sky, shortly after sunset.
- First quarter: high in the south at sunset (from mid-northern latitudes), setting around midnight.
- Full moon: rising in the east at sunset, up all night.
- Third quarter: rising around midnight, high in the sky at sunrise.
- Waning crescent: eastern sky, shortly before sunrise.
And yes, the moon is often visible in the daytime. A first quarter moon is easy to find in the afternoon sky, and a third quarter moon lingers in the morning.
Stargazing safety: Looking at the moon with your eyes, binoculars or a small telescope is perfectly safe. Never point binoculars or a telescope anywhere near the sun, though, as it can cause serious eye damage. When you head outside after dark, bring a flashlight, watch your footing, dress warmly, and choose a safe, familiar spot.
A few lovely moon facts
- We always see the same face. The moon spins once on its axis in the same time it takes to orbit Earth, so the same side always faces us. Thanks to a slight wobble called libration, we can see a little over half of its surface, about 59%, over time.
- The phases flip south of the equator. In the Southern Hemisphere, the moon appears upside down compared with the Northern Hemisphere, so a waxing moon is lit on the left.
- A blue moon isn't blue. In everyday use, it's the second full moon in a single calendar month. It happens roughly every two to three years.
- The horizon moon looks bigger, but it isn't. A rising moon can look huge, but it's the same size it is overhead. This is a well-known trick of perception called the moon illusion.
- Supermoons are real, but subtle. The moon's orbit is slightly oval, so a full moon near its closest point can look up to about 14% larger and noticeably brighter than one at its farthest point.
- Seasonal names. The Harvest Moon is the full moon closest to the autumn equinox, and the Hunter's Moon is the full moon that follows it.
Following the lunar cycle at home
Many people enjoy following the moon as a gentle monthly rhythm. In many traditions, the new moon is a time for setting intentions, and the full moon is a time for reflection, gratitude and letting go. You don't need to believe the moon changes anything to enjoy the habit. It's simply a reminder in the sky to slow down and check in with yourself.
- Keep a moon log. Each clear night, sketch the moon's shape and jot down the time and where you saw it. After a month, you'll have your own record of the whole cycle.
- Mark the four main phases. Note the new moon, first quarter, full moon and third quarter on your calendar, using a moon phase app or almanac.
- Pair it with reflection. On the new moon, write one or two intentions. On the full moon, look back on the past two weeks.
Vintage Botanical Flower Notebook
A 6 x 8-inch hardcover lined journal with a vintage botanical cover. Just the right size for a nightly moon log, with room for sketches and notes.
Shop the notebookMoon phases FAQ
How long is a full lunar cycle?
About 29.5 days from one new moon to the next. Each of the four main phases comes roughly a week apart.
Is the moon's dark side always dark?
No. The "far side" of the moon, the side we never see from Earth, gets just as much sunlight as the near side. During a new moon, the far side is fully lit.
Why isn't there an eclipse every month?
The moon's orbit is tilted about 5 degrees compared with Earth's path around the sun. Most months, the new moon passes a little above or below the sun from our view, and the full moon misses Earth's shadow.
How can I tell if the moon is waxing or waning?
From the Northern Hemisphere, a quick trick is "DOC." A moon shaped like the curve of a D is waxing, O is full, and a C shape is waning. In the Southern Hemisphere, it works the other way around.
How far away is the moon?
On average, about 239,000 miles (384,400 km). Its distance varies a little through each orbit because the path is slightly oval.
Keep watching the sky
Once you know the phases, you'll start noticing the moon everywhere: a pale half moon over the afternoon school run, a crescent hanging above the garden at dusk. When the next full moon comes around, try our full moon rituals for beginners for a simple evening of reflection. For a daily rhythm in between, our five-minute morning ritual is a sweet place to start. And keep your moon log in a vintage botanical notebook, so you can look back over the months.