Moon phase today: What the moon will look like on December 9

It's day 19 of the lunar cycle and we're close to a new lunar phase, the Third Quarter. From here, the moon will quickly get smaller each night until there's nothing left at all. That phase is known as the New Moon. But what's happening tonight, on day 19? Read on to find out.

What is today’s moon phase?

As of Tuesday, Dec. 9, the moon phase is Waning Gibbous. This means 73% of the moon is lit up tonight, according to NASA's Daily Moon Observation.

We've still got more than half of the moon on display, so for the time being there's lots to see on its surface. If you're looking up without any visual aids, keep an eye out for the Mare Tranquillitatis, Tycho Crater, and Oceanus Procellarum. If have binoculars to hand, pull these out to see the Gassendi Crater, Clavius Crater, and the Alps Mountains. If you're serious about moon gazing and have a telescope to hand, take it out to see all this plus the Apollo 15 and 16 landing spots and the Reiner Gamma.

When is the next full moon?

The next full moon will be on Jan. 3.

What are moon phases?

NASA explains that the lunar cycle (which is about 29.5 days long) is made up of the Moon’s phases, which describe how the Moon looks from Earth as it travels around us. We view the same side of the Moon at all times, but the sunlight hitting its surface shifts as it moves through its orbit. That changing illumination is what makes the Moon appear full, half-lit, or not visible at all. The cycle includes eight distinct 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.