Waning Crescent Moon

[ilan]

What is a waning crescent moon?
Deborah Byrd in MOON PHASES | September 5, 2018

A waning crescent moon is up in the east before sunrise. It’s waning toward new moon, when the moon will be between the Earth and sun.


This morning’s waning crescent moon – September 5, 2018 at 3 a.m. – from Russ Adams in Pike County, Illinois. Thanks, Russ!

In the week following last quarter moon, the moon continues to wane. You’ll see it as a waning crescent moon – sometimes called an old moon – visible in the east before dawn.

Each morning, the moon shows us less and less of its lighted side. It rises closer to the sunrise, heading for new moon.

Many people miss the waning crescent moon because it’s a morning moon, visible before sunrise. But it’s fun to follow the waning crescent day by day, as it inches into the dawn glare. Autumn is a wonderful time to see a waning crescent moon because – as dawn breaks on autumn mornings – the ecliptic stands nearly straight up with respect to the sunrise horizon. The ecliptic is the path of the sun, moon and planets. When its angle is perpendicular to the horizon, the moon is above the sunrise, rather than to one side of it, and hence easier to see.

As the moon orbits Earth, it changes phase in an orderly way.