Moonphazee
The phase
As the Moon orbits Earth, the angle between the Sun, Earth, and Moon changes. That shifting geometry is what makes the lit portion grow and shrink over the month.
Moon phases & lunar calendar
Understand the Moon, one phase at a time
Moonphazee is a plain-language resource for anyone curious about the night sky. Learn what a moon phase actually is, why the Moon seems to change shape, and how to read a lunar calendar — no telescope or astronomy degree required.
Start here
What does "moon phase" mean?
The Moon doesn't make its own light — it reflects sunlight. A "phase" simply describes how much of the Moon's sunlit half we can see from Earth on a given night.
Illumination %
Illumination is the share of the Moon's visible disc that is lit by the Sun. A New Moon is near 0%, a Full Moon is near 100%, and the quarters sit close to 50%.
Moon age
"Moon age" counts the days since the last New Moon. Because one cycle lasts about 29.5 days, a 7-day-old Moon is roughly a first-quarter Moon.
The lunar month
The eight Moon phases
One full lunar cycle moves through eight recognizable shapes. Four are "primary" phases (New, First Quarter, Full, Last Quarter) and four are the "intermediate" crescents and gibbous phases in between.
New Moon
Nearly invisible; the lit side faces away from Earth.
Waxing Crescent
A thin sliver of light grows on the right (Northern Hemisphere).
First Quarter
Half the disc is lit; the Moon is a quarter of the way around.
Waxing Gibbous
More than half lit and still brightening toward Full.
Full Moon
The entire visible face is lit; Earth sits between Sun and Moon.
Waning Gibbous
The lit area begins to shrink after Full.
Last Quarter
Half lit again, but on the opposite side from First Quarter.
Waning Crescent
A fading sliver before the cycle returns to New.
Why phases happen
How the lunar cycle works
The Moon completes one cycle of phases in about 29.5 days — a span astronomers call the synodic month. Half of the Moon is always lit by the Sun; what changes is how much of that lit half points toward Earth.
- Waxing means the lit portion is growing, from New toward Full.
- Waning means it is shrinking, from Full back toward New.
- The Moon also spins once per orbit, so the same near side always faces us.
- Phases are about geometry and lighting — they are not caused by Earth's shadow (that only happens during a lunar eclipse).
Reading the sky by date
Lunar calendar basics
A lunar calendar tracks time using the Moon's cycle instead of the Sun. Knowing the difference helps explain why dates like the New Moon shift across our everyday solar calendar.
Lunar vs solar
A solar year follows Earth's orbit around the Sun (~365 days). A lunar year is twelve synodic months (~354 days), so purely lunar calendars drift earlier relative to the seasons each year.
Lunar months
Each lunar month runs from one New Moon to the next. Many traditional calendars begin the month at the first sighting of the thin waxing crescent in the evening sky.
Reading a phase calendar
A moon-phase calendar marks the four primary phases on their dates. The days between them are the crescent and gibbous phases — waxing before Full, waning after.
Beyond the basics
Special Moon events
Some Full Moons and alignments have earned their own names. These are popular and cultural terms layered on top of the ordinary cycle — fun to spot once you know what to look for.
Full Moon names
Many traditional almanacs give each month's Full Moon a seasonal name — for example the Wolf Moon in January and the Harvest Moon near the autumn equinox. The names come from folklore and seasonal markers, not from any change in the Moon itself.
Supermoon
A Supermoon is a Full (or New) Moon that occurs near perigee, the Moon's closest point to Earth. It can look slightly larger and brighter than an average Full Moon.
Blue & Black Moons
A "Blue Moon" is commonly defined as a second Full Moon in a single calendar month. A "Black Moon" is its New-Moon counterpart — a second New Moon in a month. Neither involves an actual color change.
Lunar eclipses
A lunar eclipse happens at Full Moon when Earth passes directly between the Sun and Moon, casting its shadow on the lunar surface. During totality the Moon can take on a deep coppery-red hue.
Culture & history
The Moon in everyday life
Across history, people have woven the lunar cycle into farming, fishing, festivals, and storytelling. The notes below are cultural and historical context — not practical advice.
Gardening lore
Some traditional almanacs tied planting and harvesting to Moon phases. Today this is studied as folklore and cultural heritage rather than established agronomy.
Tides & fishing
The Moon's gravity is a real driver of ocean tides, and New and Full Moons bring the larger "spring" tides. Anglers have long timed outings to tide and Moon, a custom rooted in observation.
Festivals & folklore
Many calendars and celebrations — from lunar new-year traditions to mid-autumn festivals — are anchored to specific Moon phases, reflecting how deeply the lunar cycle shaped human timekeeping.
Note: The cultural traditions above are shared for general interest and historical context. They are not gardening, fishing, or lifestyle recommendations.
Get outside
A beginner's observing guide
You don't need fancy gear to enjoy the Moon. In fact, the most detail-rich views often come a few nights from Full rather than at Full Moon itself.
- Best phases: First and Last Quarter show the sharpest crater shadows along the day-night line (the terminator).
- Naked eye: easily reveals the dark "seas" (maria) and the overall phase.
- Binoculars: bring out larger craters and mountain ranges — a great, affordable upgrade.
- Telescope: resolves fine crater detail; a Moon filter helps tame the glare near Full.
Crater shadows are longest near the terminator — the line dividing the lit and dark sides.
Quick reference
Glossary of Moon terms
A handful of words come up again and again when talking about the Moon. Here are the essentials.
- Synodic month
- The ~29.5-day cycle from one New Moon to the next — the basis of moon phases.
- Illumination
- The percentage of the Moon's visible disc that is sunlit at a given moment.
- Terminator
- The moving line between the Moon's lit day side and dark night side.
- Waxing / Waning
- Waxing = lit area growing toward Full; waning = lit area shrinking toward New.
- Perigee / Apogee
- The Moon's closest (perigee) and farthest (apogee) points in its orbit around Earth.
- Maria
- The large dark plains on the Moon — Latin for "seas," though they hold no water.