Moon phase on December 31, 2021

Waning Crescent, 5%
🌘 Waning Crescent
Friday, December 31, 2021 · at noon (Brasília)
Illumination: 5% Age: 27.3 days Cycle: 93%

On Friday, December 31, 2021 the Moon was in its waning crescent phase, with 5% of its disk illuminated and an age of 27.3 days since the last new moon. Only a thin sliver is left, visible in the east shortly before dawn, as the cycle prepares to start over with the new moon.

Moon data for this date

Moon at noon Brasília time (UTC-3)
Phase🌘 Waning Crescent
Illumination5%
Moon age27.3 days
Day of the weekFriday
Last new moonDecember 4, 2021 at 04:43
Next full moonJanuary 17, 2022 at 20:49 (in 17.4 days)
Next new moonJanuary 2, 2022 at 15:34 (in 2.1 days)

The Moon on the surrounding days

Compare the phase and illumination over the three days before and after. Click a day to open its page.

← December 30, 2021 January 1, 2022 →

About the waning crescent

Only a thin sliver is left, visible in the east shortly before dawn, as the cycle prepares to start over with the new moon. The phase name comes from the Moon's position in its 29.53-day cycle: on December 31, 2021 it had completed 93% of the cycle that began with the new moon on December 4, 2021.

Looking for another date, such as a birthday? Use the Moon phase on the day I was born tool, see the Moon phase today page with the lunar calendar, or find the day of the week of December 31, 2021. For sun times, check sunrise and sunset.

Frequently asked questions

What is the Moon phase on December 31, 2021?

On December 31, 2021 the Moon was in its waning crescent phase, with 5% of the disk lit (calculated at noon Brasília time).

How old is the Moon on that date?

The age is the time since the last new moon: 27.3 days of an average 29.53-day cycle.

When is the next full moon after that date?

The next full moon after December 31, 2021 falls on January 17, 2022 at 20:49 Brasília time.

When is the next new moon after that date?

The next new moon after December 31, 2021 falls on January 2, 2022 at 15:34 Brasília time.

How is the Moon phase calculated?

With Jean Meeus's astronomical formulas for the instants of new, quarter and full moon. The age comes from the time since the last new moon and the illumination is (1 − cos(2π × cycle fraction)) / 2.

Is the phase the same everywhere in the world?

Yes, the phase and the illuminated percentage are the same across the planet at any given instant. Only the orientation changes: in the southern hemisphere a waxing Moon is lit on the left, in the northern one on the right.