Last Quarter Moon: Also Called Third Quarter, Half Lit and Rising Around Midnight

Some mornings you can step outside after sunrise and still find a pale half Moon hanging in the daytime sky. That is usually the last quarter Moon. NASA's Scientific Visualization Studio notes that it is often surprisingly easy to notice in the daylit sky, long after the Sun is up.

This guide explains what the phase is, why a half-lit Moon is called a quarter, how far along the 29.5-day cycle it sits, and why it rises around midnight. It also shows which side is lit in each hemisphere. At the end there is a short task in the Moon Dial.

What a last quarter Moon is

The Moon makes no light of its own. NASA's Space Place explains that moonlight is sunlight reflecting off the Moon's surface, and that the Sun always lights the half of the Moon that faces it. The U.S. Naval Observatory adds that the Moon is always half lit by the Sun, but as it orbits Earth we get to see more or less of that lit half.

At last quarter, the Naval Observatory says, one-half of the Moon appears to be lit by direct sunlight, and the lit fraction of the disk is decreasing. The share of the disk that is lit is 50 percent. This makes last quarter one of four primary phases, along with New Moon, First Quarter and Full Moon. Almanacs and calendars publish the dates and times of the primary phases.

You will also see this phase called the third quarter Moon. NASA says a last quarter Moon is also known as a third quarter Moon, and its list of eight phases uses the name third quarter. The University of Iowa's astronomy lab pages do the same, noting that Third Quarter is sometimes called Last Quarter. It is one Moon with two names.

Why it is called a quarter, and where it sits in the cycle

If half the disk is lit, why say quarter? NASA gives one answer: you are seeing half of the half of the Moon that the Sun lights, which is a quarter of the whole Moon. The Naval Observatory gives the answer from the orbit. The two half-Moon phases are called First Quarter and Last Quarter because they occur when the Moon is one-quarter and three-quarters of the way around its orbit from New Moon. NASA's Scientific Visualization Studio says the same: the quarters come when the Moon is one fourth or three fourths of the way through its cycle. So the third quarter is the one that arrives after three quarter-turns.

The cycle of phases lasts about 29.5 days on average. The Moon's age is the number of days counted from New Moon. Three-quarters of 29.5 is about 22.1, so a last quarter Moon has an age of about 22.1 days.

In the drawing, sunlight comes from the right, and the Moon has moved to the bottom of its orbit, three-quarters of the way around. From Earth, the Sun and the Moon are then about 90 degrees apart in the sky, according to the Naval Observatory. Its exact rule for almanacs compares the positions of the Moon and the Sun along the same circle in the sky. At last quarter, the Moon's position is 270 degrees more than the Sun's, which is three-quarters of a full circle.

The ages in the table are quarters of 29.5 days, rounded. The Naval Observatory also says each crescent and gibbous phase lasts about a week between the primary phases. That puts last quarter about a week after Full Moon and about a week before the next New Moon.

When it rises and sets

NASA gives a rule of thumb for most latitudes: a last quarter Moon rises around the middle of the night and sets around midday. The Scientific Visualization Studio words it the same way, saying the third quarter Moon rises around midnight. So the Moon is up through the second half of the night and into the morning, and it is still above the horizon after the Sun has risen.

A quick check shows why. NASA notes that Earth rotates once a day. The last quarter Moon sits about 90 degrees from the Sun, a quarter of a circle, so it rises and sets about a quarter of a day, or six hours, before the Sun does. If the Sun rises at 6 a.m., the Moon rises near midnight. If the Sun sets at 6 p.m., the Moon sets near noon. A chart on the University of Iowa's lab page, which treats sunrise as 6 a.m. and sunset as 6 p.m., lists the third quarter Moon as rising at midnight, highest in the sky at 6 a.m. and setting at noon.

First quarter is the mirror case. NASA says that Moon rises around midday and sets around the middle of the night, so it is an evening Moon, while last quarter is a late-night and morning Moon. The table shows how moonrise slides later as the cycle winds down. NASA says the Moon rises later and later each night.

NASA stresses that these are patterns for most latitudes. For exact moonrise and moonset times, check local predictions.

Which side is lit

Everyone on Earth sees the same phase at the same time, according to the Naval Observatory. NASA adds that people north and south of the equator see it from different angles. In the Northern Hemisphere, the University of Iowa's lab page describes the last quarter Moon as lit on its left side and the first quarter Moon as lit on its right half. NASA's Space Place agrees in spirit, calling the third quarter Moon the opposite half from the one lit at first quarter. The Iowa page also describes the waning half of the cycle as darkness creeping in from the right, so the lit part stays on the left.

If you travel to the other hemisphere, NASA says, the Moon is in the same phase but looks upside down compared with what you are used to. Turn a left-lit Moon upside down and it is lit on the right. So from the Southern Hemisphere, a last quarter Moon shows its right half bright.

Common mistakes

• Calling it a half Moon in a quiz. The casual name is fine in conversation, but the phase name is last quarter. The Naval Observatory itself puts "half Moon" in quotation marks.
• Mixing it up with first quarter. Both show half a disk. First quarter is growing and rises around midday. Last quarter is shrinking and rises around the middle of the night.
• Treating third quarter as a different phase. It is the same Moon under a second name.
• Forgetting the hemisphere. The lit half is on the left in the Northern Hemisphere and on the right in the Southern Hemisphere.
• Expecting it only after dark. The Moon sets around midday, so a last quarter Moon is still up in the morning.
• Treating the rule of thumb as exact. NASA says to check local predictions for exact times.

Try it in the instrument

Open the Moon Dial and set the sky to a Last Quarter Moon. The target is an age of about 22.1 days, three-quarters of the 29.5-day cycle, with the Moon a quarter-turn from the Sun on the orbit. The dial names an age Last Quarter when it lies within about a day of that target, and the narrower levels shrink the window.

On Bronze, the read-out under the dial gives the Moon's age, the percent lit and the phase name, and the ring is marked at 7.4, 14.8 and 22.1. On Silver you get the age and the percent lit, but no name. On Gold the read-out only says how much is lit and which edge: about 50 percent with the lit edge on the left, in the Northern Hemisphere view, is the last quarter. The same 50 percent with the lit edge on the right is the first quarter. Switch to the Southern Hemisphere view and the two edges swap. If you get stuck, Show the zone reveals the target arc for 10 points.

Questions people ask

Is a last quarter Moon the same as a third quarter Moon?

Yes. NASA says a last quarter Moon is also known as a third quarter Moon. The Naval Observatory uses Last Quarter, while NASA and the University of Iowa list the phase as Third Quarter.

How many days after New Moon is the last quarter?

About 22.1 days, three-quarters of the average 29.5-day cycle. It comes about a week after Full Moon.

What time does a last quarter Moon rise and set?

NASA says it rises around the middle of the night and sets around midday. These are patterns for most latitudes, so check local predictions for exact times.

Which side of a last quarter Moon is lit?

In the Northern Hemisphere, the left side, according to the University of Iowa. In the Southern Hemisphere, the right side, because NASA says the Moon appears upside down from the other hemisphere.

Can I see a last quarter Moon during the day?

Yes. NASA says it sets around midday, so it stays up after sunrise. NASA's Scientific Visualization Studio calls it often surprisingly conspicuous in the daylit sky long after sunrise.

Sources

• Moon Phases, NASA Science. https://science.nasa.gov/moon/moon-phases/. Opened November 10, 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 10, 2026.
• What Are the Moon’s Phases?, NASA Space Place. https://spaceplace.nasa.gov/moon-phases/en/. Opened November 10, 2026.
• Moon Phase and Libration, 2026 South Up, NASA Scientific Visualization Studio. https://svs.gsfc.nasa.gov/5588. Opened November 10, 2026.
• Part 1: Lunar Phases, Imaging the Universe, Physics and Astronomy, The University of Iowa. https://itu.physics.uiowa.edu/labs/observational/moon-and-telescopes-i/part-1-lunar-phases. Opened November 10, 2026.
• Top Moon Questions, NASA Science. https://science.nasa.gov/moon/top-moon-questions/. Opened November 10, 2026.

We opened each source ourselves on the date shown. The drawings are our own and were checked against the numbers in these sources.

Read next

• First Quarter MoonHalf of the Moon's disk is bright, yet the name says quarter.
• Waning Crescent MoonThe waning crescent is the last phase before New Moon, a thin curve of light that keeps shrinking.