As we near the New Moon, we will soon experience days with little moon visibility. We are presently on day 21 of the lunar cycle, which encompasses eight distinct phases of the moon’s visibility. The complete cycle spans approximately 29.5 days, as indicated by NASA. These phases arise as the Sun lights up various sections of the moon during its journey around Earth.

Let’s investigate what is happening with the moon this evening, Sept. 13.

What is today’s moon phase?

On Saturday, Sept. 13, the moon phase is Waning Gibbous, shining at 60% illumination from Earth’s perspective, as per NASA’s Daily Moon Observation.

What can we observe tonight? Without any visual equipment, you can see formations like the Mare Vaporum, the Tycho Crater, and the Oceanus Procellarum.

With binoculars, you can also view the Grimaldi Basin, Alphonsus Crater, and the Mare Humorum. Using a telescope, you can identify the Apollo 14 landing site, the Caucasus Mountains, and the Reiner Gamma.

When is the next full moon?

The upcoming full moon will take place on Oct. 6. The previous full moon occurred on Sept. 7.

What are moon phases?

According to NASA, moon phases emerge from the 29.5-day orbit of the moon, changing the angles between the Sun, Moon, and Earth. Moon phases portray how the moon looks from our vantage point as it travels around us. We consistently observe the same hemisphere of the moon, but the illuminated section by the Sun shifts depending on its position in orbit. This results in full moons, half moons, and moons that appear absent. There are eight main moon phases, following a recurring cycle:

New Moon – The moon sits between Earth and the sun, making the side facing us dark (not visible).

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

First Quarter – Half of the moon’s surface is lit on the right side, resembling a half-moon.

Waxing Gibbous – More than half is illuminated, but it is not yet full.

Full Moon – The entire face of the moon is illuminated and completely visible.

Waning Gibbous – The moon starts to lose illumination on the right side.

Last Quarter (or Third Quarter) – A second half-moon, with the left side illuminated.

Waning Crescent – A slender sliver of light remains on the left side before it fades to darkness again.