Crescent Moon: What It Is, When to See It, and What the Two Types Mean

A crescent moon is the lunar phase when less than half of the Moon’s lit face is visible from Earth, and it shows up twice in every 29.5-day cycle. The waxing crescent comes right after the new moon, growing a little fatter every night. The waning crescent comes right before the next new moon, fading thinner every night until it disappears. Below is what each one means, why we see it, when to step outside to catch it, and how the Almanac has used it to time planting for two centuries.

What a Crescent Moon Actually Is

The Moon does not make its own light. Half of the Moon is always lit by the Sun, the same way half of any ball in a bright room is always lit. What changes is our viewing angle. As the Moon orbits Earth, the geometry between Sun, Earth, and Moon shifts a little every day, which changes how much of the lit half we can see.

When the Moon is nearly between Earth and the Sun, the lit hemisphere faces away from us and we see almost nothing. That is the new moon. As the Moon moves along its orbit, a thin sliver of the lit hemisphere starts to come into view. That sliver is the crescent. The horns of a crescent always point away from the Sun, and the lit edge always faces toward it. If you can find the Sun, you can always tell which way the Moon is going next.

Waxing Crescent vs Waning Crescent

Waxing crescent. Comes right after the new moon. The lit portion grows from 0 percent to 50 percent over about 7.4 days. In the Northern Hemisphere, the right side of the disk is lit, which produces a shape that resembles the letter D. “Waxing” is an old verb meaning to grow.

Waning crescent. Comes in the last days before the next new moon. The lit portion shrinks from 50 percent back down to 0 percent over about 7.4 days. In the Northern Hemisphere, the left side of the disk is lit, which produces a shape that resembles the letter C. “Waning” is an old word meaning to diminish.

One catch for travelers. South of the equator, the crescents flip. Waxing looks like a backward D and waning like a backward C, because the observer’s view is inverted. So if you visit Australia or Argentina and the Moon looks “wrong,” it is just doing what the Northern Hemisphere does, only mirrored.

Where the Crescent Sits in the 8-Phase Cycle

The full lunar cycle, called the synodic month, runs 29 days, 12 hours, 44 minutes, and 2 seconds. The eight named phases in order:

1. New moon. Moon between Earth and Sun. Invisible.

2. Waxing crescent. 0 to 50 percent lit, growing. About 7.4 days.

3. First quarter. Right half lit (Northern Hemisphere). Often called a half moon.

4. Waxing gibbous. 50 to 100 percent lit, growing.

5. Full moon. Earth between Sun and Moon. Whole face lit.

6. Waning gibbous. 100 to 50 percent lit, shrinking.

7. Last quarter. Left half lit. Also a half moon.

8. Waning crescent. 50 to 0 percent lit, shrinking. About 7.4 days.

Combined, the two crescent phases account for roughly half of every cycle, which is why a crescent moon shows up so often in night-sky photos. For full dates each month, see the moon phases calendar. Curious about the TikTok pairing test? See our piece on moon phase compatibility. Curious about the TikTok pairing test? See our piece on moon phase compatibility.

When and Where to Spot a Crescent Moon

Waxing crescent. Look west, just after sunset, two to three days after the new moon. The young crescent rides low on the western horizon and sets shortly after the Sun, so you have a narrow viewing window. Get to a place with a clear horizon and minimum light pollution. The first sliver of the new lunar cycle is one of the prettiest sights in the sky, and the hardest to catch.

Waning crescent. Look east, about an hour before sunrise, two to three days before the next new moon. This is the morning crescent, lit from the bottom and the left, often hanging in the predawn pink with Venus or Mercury beside it. Worth setting an alarm.

Both crescents sit roughly 10 to 20 degrees above the horizon at their best viewing time. Binoculars are not required, but they reveal earthshine and the texture along the lit edge. Allow your eyes 15 to 20 minutes to adapt to twilight before you judge how clear the view is.

Earthshine: The Old Moon in the New Moon’s Arms

Stare at a thin crescent and you will sometimes see the dark portion of the disk glowing faintly. That ghost light is earthshine. Sunlight bounces off Earth’s clouds, oceans, and ice, hits the unlit side of the Moon, and reflects back to us. From the Moon’s surface, Earth looks roughly 50 times brighter than a full moon looks from Earth, which is why earthshine is bright enough to see at all.

Leonardo da Vinci worked out the explanation around 1510. He realized the Earth itself reflects sunlight, so the dark side of the Moon is not really dark, just faintly lit by Earthshine. Earlier sky-watchers had a more poetic name for it: “the old moon in the new moon’s arms.” Both names still get used. For why we never see the side of the Moon that produces these crescents from the back, see our piece on the far side of the moon. For why we never see the side of the Moon that produces these crescents from the back, see our piece on the far side of the moon.

Earthshine is most visible during a thin waxing crescent (a few days after new moon) or a thin waning crescent (a few days before the next new moon), and it is brightest when there is more cloud and ice on the day side of Earth.

How to Photograph a Crescent Moon

The bright lit edge of a crescent is much brighter than the rest of the scene, which is what makes phone-camera shots so often disappoint. A few practical settings carry most of the work.

For the lit edge alone. Use NASA’s “Looney 11” rule. Set aperture to f/11, shutter speed to 1 over the ISO (so ISO 100 = 1/100 second, ISO 200 = 1/200 second). Manual focus to infinity. Spot meter on the Moon.

For a thin crescent with earthshine. Open the aperture to f/5.6 to f/8, push ISO to 400 to 800, and slow the shutter to 1/30 to 1/8 second. A tripod is essential. The lit edge will overexpose slightly, but the dark side will hold detail.

For composition. Catch the Moon during civil twilight, when the sky still has color, so the foreground does not silhouette into pure black. A 200 mm or longer lens is ideal for filling the frame. White balance daylight (5500 K) keeps the lunar color natural.

The Crescent Moon and Almanac Planting Tradition

Farmers’ Almanac has used the moon as a planting calendar since 1818. The basic rule, drawn from older European and North American farming traditions, is straightforward.

Waxing moon, including the waxing crescent through first quarter, is the time to plant aboveground crops. Tomatoes, beans, peppers, lettuces, corn, melons, squash. The increasing moonlight is traditionally said to encourage leaf and stem growth.

Waning moon, including the waning crescent, is the time to plant root crops. Carrots, beets, onions, garlic, potatoes, turnips. The decreasing moonlight is traditionally said to encourage root development.

Direct scientific evidence for moon-phase planting is limited. The tradition has held up for two centuries because it produces a planting calendar that gardeners actually follow. We give the dates and the framework. Try it for a season against a control row planted off-phase. Decide for yourself. For the current month’s lunar planting windows, see our gardening by the moon calendar.

Cultural and Calendar Use

The crescent moon has marked time for as long as people have looked up. The Islamic calendar is purely lunar, and the start of each month is set by the first sighting of a young crescent after a new moon. The start of Ramadan and the date of Eid both depend on local crescent observation, which is why dates can shift by a day or two between countries. Symbol use spans flags, mosque architecture, and historical Ottoman heraldry.

For pre-electric navigators, the crescent’s horns served as a rough compass. In the Northern Hemisphere, a line drawn from the bottom horn through the top horn and extended down to the horizon points roughly south. Sailors and travelers used the trick for centuries before celestial navigation tools became standard.

Frequently Asked Questions

What is a crescent moon?

A crescent moon is the lunar phase when less than 50 percent of the Moon’s illuminated face is visible from Earth. It happens twice in every 29.5-day cycle: once as a waxing crescent (growing, just after the new moon) and once as a waning crescent (shrinking, just before the next new moon).

What is the difference between waxing and waning crescent?

Waxing crescent grows from 0 to 50 percent illumination over about 7.4 days right after the new moon, and is lit on the right side in the Northern Hemisphere (looks like a D). Waning crescent shrinks from 50 to 0 percent illumination over about 7.4 days right before the next new moon, and is lit on the left side (looks like a C).

When is the best time to see a crescent moon?

Look west just after sunset for the waxing crescent, two to three days after the new moon. Look east about one hour before sunrise for the waning crescent, two to three days before the next new moon. Both sit low on the horizon, so a clear view in that direction matters most.

Why does the crescent moon glow on its dark side?

That faint glow is called earthshine. Sunlight bounces off Earth’s clouds, oceans, and ice and reflects back to dimly illuminate the unlit portion of the Moon. Leonardo da Vinci first explained the effect around 1510. The traditional name for it is “the old moon in the new moon’s arms.”

Is a crescent moon good for planting?

By Farmers’ Almanac tradition, the waxing crescent is ideal for planting aboveground crops like tomatoes, beans, lettuce, and corn. The waning crescent is the time to plant root crops like carrots, beets, onions, and potatoes. Direct scientific evidence for moon-phase planting is limited, but the tradition produces a usable calendar that gardeners have followed for two centuries.

How long does the crescent moon phase last?

Each crescent phase lasts approximately 7.4 days, one quarter of the 29.5-day lunar cycle. Combined, you can see a crescent moon roughly 14.8 days out of every lunar month, or about half the time.