Moon Astrology · Guide

Full Moon, New Moon, Ekadashi: A Plain-English Guide to the Lunar Month

The Cosmic Veda · Princeton, NJ · Plain-English Vedic astrology

Long before wall calendars, people planned by the Moon — and the Vedic tradition turned that instinct into a precise system. The lunar month is divided into 30 "lunar days," each defined by how far the Moon has traveled from the Sun. A few of those days are waypoints: natural pauses, peaks, and resets that millions of households still observe.

Here's what each waypoint actually is, what it's traditionally for, and how to use the rhythm without needing a glossary. (Everywhere on this site, English leads and the traditional Sanskrit term is offered alongside — that's our house rule.)

First, what is a "lunar day"?

A lunar day — traditionally called a tithi — is one-thirtieth of the lunar month. Each lunar day covers 12° of separation between the Moon and Sun. Because the Moon's speed varies, a lunar day isn't exactly 24 hours; it runs about 19 to 26 hours. That's why fasting days sometimes fall on different weekdays than you'd guess, and why a proper calendar computes them astronomically rather than counting calendar squares.

The month has two halves: the bright half (new moon to full moon, the Moon growing) and the dark half (full moon back to new, the Moon releasing). Growth, then release — the whole philosophy of lunar living is in that one sentence.

The four waypoints of the month

🌕 Full Moon

Completion and gratitude

Traditional name: Purnima — lunar day 15 of the bright half

The Moon stands opposite the Sun, fully lit. Traditionally a day for completion, celebration, gratitude, and acts of generosity — many of the great festivals (Guru Purnima, Sharad Purnima, Holi's eve) fall on full moons. Emotionally, feelings tend to run high and visible. A good day to finish, appreciate, and share; a less ideal day to start brand-new ventures.

🌑 New Moon

Rest and quiet beginnings

Traditional name: Amavasya — lunar day 30, the dark half's end

Moon and Sun stand together; the night is dark. The tradition treats this as an inward day — rest, reflection, and honoring ancestors. It is not an "unlucky" day (we don't do fear here); it's a fallow day, the way good soil needs fallow seasons. Plans seeded quietly at the new moon grow with the waxing fortnight that follows.

✨ Lunar Day 11

The lightness day

Traditional name: Ekadashi — the 11th day of each half, so twice a month

The most widely observed fasting day in the Vedic world. Traditionally kept with a light or simplified diet (many households simply skip grains), extra prayer or study, and a general easing of consumption. The logic is beautifully practical: twice a month, travel light — digestively, mentally, materially. If you adopt only one lunar practice, this is the gentlest place to begin. Any fasting practice should, of course, respect your own health needs.

◐ Eclipses

The pause points

Traditional name: Grahana — special full and new moons when shadows align

A few times a year, the full or new moon coincides with an eclipse. The tradition treats these as pause points: keep the day gentle, favor reflection over launches, and let big decisions wait a day. No doom, no drama — just the calendar's way of saying "not every day is for pushing forward."

Using the rhythm (without reorganizing your life)

One more layer: these waypoints are universal — the same for everyone. Your personal lunar rhythm comes from your birth Moon: which days are naturally supportive or restful for you depends on the mansion your Moon occupied at birth. That's the difference between a moon app and Moon astrology.

See the next 12 months at a glance

Every full moon, new moon, lunar day 11, and eclipse — computed live, marked clearly. Plus your personal Moon sign, free.

Open the lunar calendar

Continue reading: Moon sign vs Sun sign · Why the Moon comes first