Moon Phase Today

How to read today’s moon phase

The Moon never changes shape. Half of it is always lit by the Sun; what changes is how much of that lit half is turned toward Earth. As the Moon circles us roughly once every 29.5 days, the angle between the Sun and the Moon in our sky opens from 0° (new moon) to 180° (full moon) and closes again. This tool measures that angle for the moment you are looking at and turns it into the four numbers people ask about most.

Phase name

There are eight named phases. Four are exact moments: New Moon, First Quarter, Full Moon and Last Quarter. The other four are the stretches in between: Waxing Crescent, Waxing Gibbous, Waning Gibbous and Waning Crescent. “Waxing” means the lit part is growing night by night; “waning” means it is shrinking. Because a full moon is technically an instant, the tool labels the Moon “full” for about half a day either side of the exact time, which matches what you see when you look up.

Illumination and Moon age

Illumination is the share of the Moon’s disc that appears lit, from 0% at new moon to 100% at full. It does not rise at a steady rate: it changes fastest around the quarters and slowest near new and full, which is why the Moon looks “full” for two or three nights. Moon age is simply the number of days since the last new moon, counting up to about 29.5 before it resets.

The Moon’s zodiac sign

The Moon moves through all twelve signs in about 27.3 days, spending roughly two and a half days in each. The sign shown here uses the tropical zodiac, the system behind Western horoscopes. A new moon always falls in the same sign as the Sun, and a full moon in the opposite sign, so a Libra-season full moon is always in Aries. The tool also tells you when the Moon next changes sign, which is useful if you plan by it.

Northern and Southern Hemisphere views

Everyone on Earth sees the same phase on the same night, but not the same way up. North of the equator a waxing moon is lit on the right; south of it, on the left, because observers there are effectively standing upside down relative to the north. Near the equator a crescent often looks like a bowl or a smile. Use the toggle to match the drawing to your sky. It only flips the picture; the phase, percentage and dates stay the same.

How the calculation works

Nothing is looked up from a server. Your browser computes the ecliptic longitudes of the Sun and Moon using the standard series from Jean Meeus’s Astronomical Algorithms, then finds the next new and full moon by solving for the instant the two line up or sit opposite. The Moon’s position is good to a small fraction of a degree and phase times to within a few minutes, which is ample for planning, gardening, photography or ritual timing. It is not meant for navigation or eclipse prediction.

Using the phase in everyday planning

A simple rhythm many people follow: set intentions and begin things around the new moon, build and push during the waxing half, review and celebrate at the full moon, then finish, tidy and rest as the light wanes. You do not need to believe the Moon causes anything for this to be useful. A repeating two-week cue to start and a two-week cue to review is a steady habit loop in its own right.