The Moon phase cycle, explained
- Phases come from the changing angle between Sun, Earth and Moon - not from Earth's shadow.
- One full cycle (new → full → new) is the synodic month: about 29.53 days.
- The four primary phases are instants; the four in-between phases are the weeks spanning them.
The eight phases in order
| Phase | Type | Sun–Moon angle | Lit side visible | When visible |
|---|---|---|---|---|
| New Moon | Primary | 0° | ~0% | Up with the Sun (not visible) |
| Waxing Crescent | Intermediate | 0–90° | rising | Evening, west |
| First Quarter | Primary | 90° | 50% | Afternoon to midnight |
| Waxing Gibbous | Intermediate | 90–180° | rising | Late afternoon to late night |
| Full Moon | Primary | 180° | 100% | All night |
| Waning Gibbous | Intermediate | 180–270° | falling | Late night to morning |
| Last Quarter | Primary | 270° | 50% | Midnight to noon |
| Waning Crescent | Intermediate | 270–360° | falling | Morning, east |
Synodic vs sidereal: two different months
The Moon takes about 27.3 days to orbit Earth once relative to the stars - the sidereal month. But while it orbits, Earth is also moving around the Sun, so the Moon needs roughly two extra days to 'catch up' to the same Sun–Earth–Moon alignment.
That alignment cycle - the time between one new moon and the next - is the synodic month, about 29.53 days. Phases follow the synodic month, which is why a calendar month usually holds one full moon, and occasionally two (a 'blue moon').
Waxing, waning, gibbous, crescent
'Waxing' means the lit portion is growing (new toward full); 'waning' means it is shrinking (full toward new). 'Crescent' is less than half lit; 'gibbous' is more than half but not full.
A lunar eclipse is a separate event: it only happens at a full moon when the Moon passes through Earth's shadow, which is why eclipses are rare rather than monthly.
Lunar perigee and apogee in 2026 (UTC) - 27 passages
| Date | Time (UTC) | Passage | Distance (km) |
|---|---|---|---|
| Jan 1 | 21:44 | Perigee | 360,336 |
| Jan 13 | 20:46 | Apogee | 405,429 |
| Jan 29 | 21:47 | Perigee | 365,860 |
| Feb 10 | 16:52 | Apogee | 404,567 |
| Feb 24 | 23:11 | Perigee | 370,125 |
| Mar 10 | 13:43 | Apogee | 404,374 |
| Mar 22 | 11:38 | Perigee | 366,846 |
| Apr 7 | 08:31 | Apogee | 404,960 |
| Apr 19 | 06:55 | Perigee | 361,618 |
| May 4 | 22:31 | Apogee | 405,828 |
| May 17 | 13:44 | Perigee | 358,064 |
| Jun 1 | 04:30 | Apogee | 406,356 |
| Jun 14 | 23:20 | Perigee | 357,186 |
| Jun 28 | 07:11 | Apogee | 406,256 |
| Jul 13 | 07:56 | Perigee | 359,102 |
| Jul 25 | 16:44 | Apogee | 405,538 |
| Aug 10 | 11:18 | Perigee | 363,273 |
| Aug 22 | 08:20 | Apogee | 404,632 |
| Sep 6 | 20:44 | Perigee | 368,249 |
| Sep 19 | 02:59 | Apogee | 404,210 |
| Oct 1 | 20:52 | Perigee | 369,324 |
| Oct 16 | 22:54 | Apogee | 404,632 |
| Oct 28 | 18:04 | Perigee | 364,397 |
| Nov 13 | 17:50 | Apogee | 405,608 |
| Nov 25 | 21:02 | Perigee | 359,335 |
| Dec 11 | 06:44 | Apogee | 406,407 |
| Dec 24 | 08:32 | Perigee | 356,641 |
The distance the phase table leaves out
The Moon's orbit is an ellipse, so its distance swings by roughly 40,000 km every month. In 2026 the closest perigee is 356,641 km on Dec 24 and the farthest apogee is 406,407 km on Dec 11 - a difference of about 50,000 km, which changes the Moon's apparent diameter by around 14%.
A "supermoon" is simply a full moon that happens near perigee, and a "micromoon" one near apogee. Neither is a defined astronomical term, and the size difference is hard to judge by eye without a side-by-side comparison, because there is nothing in the sky to measure against. Comparing this table with the phase dates shows which full moons of the year fall closest to perigee.