Find out what phase the Moon is in on any date — including today — and learn what each lunar phase means.
The Moon goes through 8 main phases during its roughly 29.5-day lunar cycle. Use the calculator below to find the Moon's phase on a specific date, including today's Moon phase.
Choose any date to see the estimated lunar phase for that day. You can check today's Moon phase or look ahead to plan a stargazing session.
This calculator provides an estimated lunar phase based on the Moon's approximately 29.5-day synodic cycle.
The Moon does not make its own light. It reflects light from the Sun. At any moment, half of the Moon is illuminated by sunlight, but the amount of that illuminated half that we can see from Earth changes as the Moon orbits our planet.
The Moon takes about 29.5 days to go through one complete cycle of phases, from one New Moon to the next. The changing appearance is called the Moon's lunar phase.
Moon phases are not caused by Earth's shadow. Earth's shadow only causes the Moon to darken during a lunar eclipse. Normal phases happen because our viewing angle changes as the Moon travels around Earth.
The lunar cycle is commonly divided into eight main phases. The Moon gradually changes from New Moon to Full Moon and then back again.
The Moon's illuminated side faces away from Earth, making it difficult to see.
A small illuminated crescent grows larger each day.
About half of the Moon's visible face is illuminated.
More than half is illuminated and the Moon is approaching Full Moon.
Nearly the entire Earth-facing side is illuminated.
More than half remains illuminated, but the lit portion is shrinking.
About half of the visible face is illuminated again, opposite the First Quarter.
A thin illuminated crescent shrinks toward the next New Moon.
The best Moon phase depends on what you want to observe. A bright Moon can be beautiful to look at, but its light can make faint stars and deep-sky objects harder to see.
Around New Moon, the Moon contributes very little light to the night sky. This makes dark-sky conditions better for observing faint objects such as galaxies, nebulae, and the Milky Way.
A Full Moon is excellent for observing the Moon itself, but its brightness can wash out many faint stars and deep-sky objects.
First and Third Quarter phases are especially interesting for lunar observing. Shadows along the boundary between the illuminated and dark portions can make craters, mountains, and other surface features easier to see.
Use the calculator to check the Moon's phase before heading outside. Then visit our stargazing guide for more ideas about what to observe.
The Moon phase calculator estimates the lunar phase by comparing a selected date with the repeating lunar cycle. One complete synodic cycle — from one New Moon to the next — lasts about 29.5 days.
Because the calculation is an approximation based on the lunar cycle, the result should be treated as an estimate rather than a precise astronomical ephemeris. For general learning and stargazing planning, it provides a useful way to understand where a date falls within the lunar cycle.
The words waxing and waning describe whether the illuminated portion of the Moon is growing or shrinking from our perspective on Earth.
Select today's date above and choose Calculate Moon Phase to see the estimated lunar phase for today.
The Moon has eight commonly recognized phases: New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Third Quarter, and Waning Crescent.
A complete cycle from one New Moon to the next takes about 29.5 days. This is called the Moon's synodic period.
The Moon does not actually change shape. As it orbits Earth, we see different amounts of its Sun-illuminated half.
A Full Moon is bright and easy to notice, but it is not always the best phase for seeing surface detail. During First and Third Quarter, shadows near the day-night boundary can make craters and mountains stand out more clearly.
New Moon and the nights around it generally provide darker skies, making faint stars, galaxies, nebulae, and the Milky Way easier to observe.
No. Normal Moon phases are caused by the changing angle between the Sun, Earth, and Moon. Earth's shadow causes a lunar eclipse, which is a different event.
Yes. Depending on its phase and position in the sky, the Moon can be visible during daylight hours as well as at night.
Curious about more than the Moon? Explore our stargazing resources to learn about constellations, observing conditions, and the night sky.