How to Tell Time by the Moon?

When your watch is gone and the Moon is the brightest thing up, name the phase before you judge how high it sits. How to tell time by the moon starts with that order, because each phase rises at its own time of day. The same spot in the sky is an evening hour for a full Moon, mid-afternoon for a first-quarter Moon, and the middle of the night for a last-quarter Moon.

This page gives you the eight phase times, the steps for turning height into an hour, the reason tomorrow’s Moon is later, and the ordinary corrections for daylight saving time, season, and which half of Earth you live on. It also shows a paper wheel that holds the same clock in your hands.

Which Moon Phase Is Up at Which Hour?

The Moon has no light of its own, the Sun lights one half, and the phase is how much of that bright half is turned toward you. At new Moon the Moon sits near the Sun, so it rises and sets with the Sun, and the bright face points away from Earth. The sky looks empty of a Moon even though the Moon is up all day.

A full Moon is the opposite case. It stands opposite the Sun, rises around sunset, reaches its highest point around midnight, and sets around sunrise, so it is up all night. Outside the polar circles you will not see a full Moon high in a midday sky. The phases between new and full split that difference, which is why a half-lit Moon and a crescent keep different hours.

Waxing means the bright part is growing, from the crescent after new Moon through first quarter to the gibbous shape before full. Waning means it is shrinking, from the gibbous shape after full through last quarter, also called third quarter, and back to a thin crescent. North of the equator a waxing Moon is lit on the right as you look at it. South of the equator that side flips, and near the equator a young crescent often lies on its back like a smile, because the Sun’s path drops steeply past the horizon.

NASA astronaut Anne McClain shows each of those shapes from the space station in a short classroom film, which helps if the names still blur together.

The hours below are the pocket version of that cycle, the one classroom dials use, drawing on why each moon phase rises at its own hour. Read them as local standard time on a day when sunrise and sunset fall near the classic morning and evening marks. Each phase is treated as staying up for about half a day. What changes is which half.

A waxing crescent is a late-day and early-evening Moon, already low in the west not long after sunset. A waning crescent is a morning Moon, up before the Sun and gone by afternoon. Neither belongs overhead at midnight. First quarter is the half-lit Moon you can catch from noon through the first half of the night. Last quarter is the half-lit Moon of the hours from midnight through the morning.

How to Tell Time by the Moon Once You Know the Phase

With the phase named, the hour is how far the Moon has walked the path in its own row. Low in the east means it rose not long ago. Halfway from that horizon up toward the top of its path means it is about a quarter of the way through its time above the horizon. At the top of the path it is in the middle of that window. Low in the west means it is close to setting.

From the northern half of the world, the top of the path is in the south. From the southern half, the top of the path is in the north. The Moon still rises in the eastern half of the horizon and sets in the western half in both places, as long as you are outside the polar circles.

1. Name the phase you see, as full, half, crescent, or gibbous, and note whether the bright part is on the waxing side or the waning side for where you live.
2. Find that phase on the table, and take its rise time as the start of the trip and its set time as the end, with the highest point in the middle.
3. Place the Moon on the path from the eastern horizon, up to its highest point, then down toward the western horizon.
4. Turn that place into a rough hour by splitting the trip into even parts, the way the table splits rise, highest, and set.

Hold the height still and change only the phase. Halfway up in the east is not one shared hour.

The full Moon row reads about 9 p.m. for that halfway spot in the east. The first-quarter row reads about 3 p.m. for the same spot, and the last-quarter row reads about 3 a.m. Use the row for the phase you actually see.

A half Moon lit on the waxing side, already high in the south during a late northern afternoon, sits near the highest cell for first quarter, which is sunset. An afternoon Moon on a clear blue sky is the normal first-quarter view. A bright gibbous Moon before sunset is the waxing gibbous row, already up since mid-afternoon and headed for a late-night set.

Why Does the Moon Rise Later Each Day?

The table matches the night of the named phase, and the days pressed close to it. The Moon keeps moving east against the stars as it orbits, so Earth has to turn a little farther each day before that Moon clears the horizon. Moonrise comes about 50 minutes later than it did the day before.

That nightly slide is why a shape you would still call gibbous is not stuck on one row. The night after a full Moon, the disk is a little less than full and it rises later than the night before. Keep calling every nearly full Moon “full,” and your guessed hour drifts later each evening while you treat the clock as fixed.

A week of later rises is what carries the pocket clock from one main phase to the next, which is why first quarter sits a quarter of a day away from new Moon on the table, and full Moon a quarter of a day away from first quarter. You can check the mean length of a lunation for the precise length of the cycle from one new Moon to the next. That cycle is what the daily slide is spreading across the month.

What Moves the Pocket Moon Times Off the Clock?

The pocket times are a clean sketch. Three ordinary facts move a real moonrise off those marks, and none of them requires a new method. You still name the phase, then you shift the hour.

Daylight Saving Time and the Moon Clock

ADD ONE HOUR

• The correction: While your civil clocks are on daylight saving time, add one hour to every pocket time before you compare it with a watch.
• Why the wheel agrees: The paper moon calendar from NASA is drawn in standard time and prints the same add-one-hour note for daylight saving time.

The Moon still rises near sunset on the full Moon row. Sunset on the wall clock is an hour later than standard time while daylight saving time is in force, so a pocket time of sunset can read an hour later in the kitchen.

Latitude, Season, and Moonrise

Sunset in midsummer and midwinter is not the sunset of a March or September day for most places people live. Because a full Moon rises near sunset, its clock time follows that season. Early sunsets mean an early full-Moon rise, and late sunsets mean a late one. The pocket mark of about 6 p.m. is the sketch for a day when sunset itself falls near then.

Your latitude also changes how high the Moon climbs and how long it stays up. A Moon that passes nearly overhead at one latitude skims lower at another, so “halfway up” is a judgment of the path you see, not a fixed number of degrees you must measure. The order of that path, east then high then west, is the part that stays put.

The Moon Clock South of the Equator

The rise and set hours do not swap when you cross the equator. What changes is the direction you face and which side of the disk is bright.

• Face north, not south, to watch the Moon cross the sky, so west sits on your left as the night goes on.
• A waxing Moon is lit on the left, and a waning Moon is lit on the right, the reverse of the northern view.
• The northern memory aid that says light on the right means waxing will name the phase backward if you use it in the south.

Once the phase is named correctly, you use the same table. A full Moon still rises near sunset and stands highest around midnight. A first-quarter Moon still rises around noon. Only the face you turn toward the Moon, and the bright side you trust, have changed.

Build a Paper Moon Phase Wheel

If you would rather turn a dial than hold the table in your head, NASA’s moon phases calendar and calculator is three paper wheels joined by a brass fastener. The build takes under 30 minutes. You need scissors, tape, a hole punch, a pencil or a black marker, and the template printed two-sided on heavy paper or cardstock. Printing beats photocopying, because a copy can shift the alignment of the two sides.

If the phase names are still new, fill in a simple moon journal from NASA before you shade the wheel. The shading is the part that locks the shapes to the labels.

1. Print the template two-sided, then shade the phases on the Moon Phases Wheel to match the labels before you cut anything.
2. Cut out the Moon Phases Wheel, the Viewing Wheel, and the moonrise and moonset panels, and punch the hole marked for the view from space.
3. Tape the moonrise and moonset panels onto the Viewing Wheel where the sheet shows, then poke a center hole through all three wheels with a pencil.
4. Stack the Moon Phases Wheel on the Calendar Wheel, put the Viewing Wheel on top, and join the stack with the brass fastener.

How to Read the E, S, and W Windows

Pick a date on the calendar wheel and turn the phases wheel until the shapes match. Center that match above the S on the viewing window.

• The E window: That phase rises in the eastern sky at the time shown beside E.
• The S window: The time above S is when that phase is high while you face south, which is the northern-hemisphere design of this wheel.
• The W window: That phase sets in the western sky at the time shown beside W.

The dates on the calendar wheel are the dates of the phases in the Pacific Time Zone. The hours in the windows are the same standard-time sketches as the table on this page, not a city almanac and not Pacific clock time for your moonrise. Add one hour while daylight saving time is in effect. If you built the wheel last year, keep the shaded phases wheel and print a new calendar wheel and viewing wheel for the new year.

On that wheel, waiting for a full Moon to rise in the east is the easier watch. Seeing that same full Moon set means being awake for a moonset in the early morning, before the about 6 a.m. mark on the pocket clock. The wheel and the table are telling you one fact: the full Moon owns the night, and the comfortable view is moonrise, not moonset.

Mistakes That Throw Off a Moon Time Reading

Most bad guesses come from a right observation fed into the wrong row. Check the phase against the list before you trust the hour.

CHECK THESE MOON TIME MISTAKES

• Skipped phase: The same height in the east can be evening, afternoon, or the small hours, and only the phase picks which.
• Swapped quarters: First quarter is the half Moon of the afternoon and evening, and last quarter is the half Moon from midnight through the morning.
• Crescent at midnight: A waxing crescent is already setting in the late evening, and a waning crescent does not rise until the early morning.
• Southern lit side: Light on the right means a waxing Moon only north of the equator, and the same rule in the south names the phase backward.
• Minute by minute: The pocket times are a sketch for a rough hour, not a match you can set a watch by.

Your eye can separate a crescent, a half Moon, and a full Moon, and that is the split this method uses. It will not separate one gibbous night from the next, because those nights share a shape while the rise keeps sliding later. Cloud, glare from the Sun, and a Moon that has already set all leave you with nothing to read. On those nights, yesterday’s phase plus the later rise, or the paper wheel set to today’s date, is the stand-in.

Frequently Asked Questions

Can You Tell Time by a New Moon?

You cannot, because a new Moon rises and sets with the Sun and its bright face points away from Earth, so there is no disk to place in the sky. The thin crescent a couple of nights later, low in the west after sunset, is the first shape this clock can use. The thin crescent before the next new Moon shows up low in the east before sunrise, and that one is a morning clock instead.

Why Is the Moon Out in the Afternoon?

An afternoon Moon is what the first-quarter and waxing gibbous rows predict, since those phases rise around midday or mid-afternoon and are already up before sunset. You can run the same steps in daylight that you would use at night. The Sun, still up, shows you which side of the sky is west, and the Moon’s phase shows you which row you are on.

Can the Moon’s Shape Give You the Date?

The shape can tell you roughly how far you are from new Moon or full Moon, on the order of a week for each quarter of the cycle, but it cannot give you a calendar date. Gibbous nights look alike to the eye, and the exact instant of full Moon may fall during your daytime. For a date, use a calendar or the paper wheel rather than the outline of the disk.

Does the Moon Clock Work Near the Poles?

The east-to-west method needs the Moon to rise and to set. Inside the polar circles there are stretches when the Moon stays above the horizon, or stays below it, for much longer than a normal night, the way the summer or winter Sun does. The pocket table does not cover those days, and a height above the horizon there is not a simple fraction of a 12-hour trip.

The next clear night, name the phase before you read the height. Halfway up in the east belongs to the full Moon row alone, and the next night that row starts about 50 minutes later.