Moon Phase Today: December 18, 2025 Lunar Appearance Explained

Key Points

• Current Phase: As of December 17, the moon phase is a Waning Crescent, with only 2% illumination.
• Next Full Moon: The next full moon is scheduled for January 3, following the last full moon on December 4.
• Lunar Cycle: The lunar cycle lasts approximately 29.5 days and includes eight main phases.
• Visibility: With a small sliver of moonlight, observing details on the moon’s surface is unlikely tonight.

We’re close to the New Moon, which means it’s almost the beginning of a new lunar cycle. The lunar cycle is the roughly 29.5-day period during which the Moon orbits Earth and appears to change shape as different portions of its sunlit surface become visible from our perspective.

What is today’s moon phase?

As of Thursday, Dec. 17, the moon phase is Waning Crescent. This means only 2% of the moon is lit up tonight, according to NASA’s Daily Moon Observation.

With such a small sliver of moon on display, it’s unlikely you’ll be able to see anything on its surface tonight.

When is the next full moon?

The next full moon will be on Jan. 3. The last full moon was on Dec. 4.

What are moon phases?

According to NASA, the Moon takes around 29.5 days to complete one full cycle. During this time, it passes through a series of phases as it orbits Earth. Although the same side of the Moon always faces us, the amount of sunlight reflecting off its surface changes, which is why it can appear fully illuminated, partly lit, or completely invisible at different points in the cycle. This process is divided into eight main lunar phases:

New Moon – The moon is between Earth and the sun, so the side we see is dark (in other words, it’s invisible to the eye).

Waxing Crescent – A small sliver of light appears on the right side (Northern Hemisphere).

First Quarter – Half of the moon is lit on the right side. It looks like a half-moon.

Waxing Gibbous – More than half is lit up, but it’s not quite full yet.

Full Moon – The whole face of the moon is illuminated and fully visible.

Waning Gibbous – The moon starts losing light on the right side. (Northern Hemisphere)

Third Quarter (or Last Quarter) – Another half-moon, but now the left side is lit.

Waning Crescent – A thin sliver of light remains on the left side before going dark again.