Moon Phases Explorer
Drag the Moon around the Earth to see why its shape changes, then find the phase, Purnima, Amavasya and tithi for any date.
The Moon's phases happen because we see different amounts of its sunlit half as it orbits the Earth — the Earth's shadow plays no part. The eight phases run New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter and Waning Crescent, and the cycle repeats every 29.53 days.
View from above the North Pole
Sunlight comes from the right. Drag the Moon or use the slider. The yellow edge marks the half of the Moon that faces Earth.
As seen from Earth
Moon phase on any date
Times are in Indian Standard Time (IST).
How the date is worked out
Moon calendar
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Moon shown at 9 pm IST each day. Labels give the time (IST) of each principal phase. Tap a day to see it above.
Next Purnima & Amavasya
Exact moments of full and new moon after the chosen date (IST).
| Event | Date | Time (IST) | Eclipse? |
|---|
Eclipse column: a solar or lunar eclipse happens somewhere on Earth at that moment (it may not be visible from India). Festival dates in a panchang can fall a day earlier or later, because a tithi is counted from local sunrise.
Phases are not eclipses
Side view — the tilt of the Moon’s orbit is exaggerated so you can see it.
- Phases happen because we see different amounts of the Moon’s sunlit half as it orbits us. Earth’s shadow plays no part.
- The Moon’s orbit is tilted about 5°, so at most full and new moons it passes above or below the Sun–Earth line.
- Only when a full or new moon happens near a crossing point (a node) do we get a lunar or solar eclipse — about 4 to 7 eclipses a year.
Why the Moon changes shape
Half of the Moon is always lit by the Sun. As the Moon goes around the Earth, we see more or less of that bright half.
Move the Moon
Drag it around its orbit or press play to run through a whole lunar month.
Watch the shape
The panel on the right shows the Moon exactly as it looks from India for that position.
Pick a date
Find the phase, illumination, tithi and the next Purnima and Amavasya for any day from 1900 to 2100.
Browse a month
The calendar shows every night’s Moon — print it for your class notice board.
The eight phases
New Moon → Waxing Crescent → First Quarter → Waxing Gibbous → Full Moon → Waning Gibbous → Last (Third) Quarter → Waning Crescent → New Moon.
Waxing = lit part growing; waning = shrinking. From India, a waxing Moon is lit on the right side.
Synodic month
1 lunar month ≈ 29.53 days
The Moon orbits Earth in 27.3 days, but Earth also moves around the Sun meanwhile, so the Moon needs about 2 extra days to line up with the Sun again.
Paksha and tithi
The bright fortnight from Amavasya to Purnima is Shukla Paksha; the dark fortnight back to Amavasya is Krishna Paksha. Each tithi is the time the Moon takes to gain 12° on the Sun, so a lunar month has 30 tithis.
How much is lit?
Lit fraction = (1 − cos E) ÷ 2
E is the angle between the Sun and the Moon as seen from Earth: 0° at new moon (0% lit), 90° at first quarter (50%), 180° at full moon (100%).
Moon Phases Explorer — your questions
Why does the Moon change shape?
Half of the Moon is always lit by the Sun. As the Moon travels around the Earth we see different amounts of that bright half, which is what we call phases. The Earth's shadow has nothing to do with it — that only happens during a lunar eclipse, which is a separate and much rarer event.
What are the eight phases of the Moon in order?
New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last (or Third) Quarter and Waning Crescent, then back to New Moon. At New Moon 0% is lit, at the quarters 50% and at Full Moon 100%. The lit fraction is (1 − cos E) ÷ 2, where E is the Sun-Moon angle seen from Earth.
What is the difference between waxing and waning?
Waxing means the lit part is growing, from New Moon to Full Moon; waning means it is shrinking, from Full Moon back to New Moon. Seen from India and the rest of the Northern Hemisphere, a waxing Moon is lit on its right side and a waning Moon on its left. In the Southern Hemisphere it is the other way round.
Why is a lunar month 29.5 days and not 27.3 days?
The Moon completes one orbit of the Earth in 27.3 days, but the Earth has meanwhile moved along its own orbit around the Sun. The Moon needs about two extra days to line up with the Sun again and return to the same phase, giving a synodic month of about 29.53 days — the month the calendar of phases follows.
What are Purnima, Amavasya and tithi?
Purnima is the full-moon day and Amavasya the new-moon day. The bright fortnight from Amavasya to Purnima is Shukla Paksha and the dark fortnight back is Krishna Paksha. A tithi is the time the Moon takes to gain 12° on the Sun, so a lunar month has 30 tithis. Panchang dates can differ by a day because a tithi is counted from local sunrise.
Why don't we get an eclipse at every full moon?
The Moon's orbit is tilted about 5° to the Earth's orbit around the Sun, so at most full and new moons the Moon passes above or below the Sun-Earth line. Only when a full or new moon happens near a crossing point, called a node, do the three line up — which gives about four to seven eclipses a year.
Which Indian festivals fall on full moon and new moon days?
Holi, Raksha Bandhan, Guru Purnima and Buddha Purnima all fall on Purnima, the full-moon day. Diwali is celebrated on an Amavasya night, when the sky is darkest. Eid begins when the thin new crescent is first sighted after the new moon, which is why its date depends on an actual sighting.