When the lighted portion of the moon visible from Earth is decreasing each evening, it's called a waning moon.

Here's a breakdown:

* Waxing: Means the illuminated portion of the moon is getting bigger.

* Waning: Means the illuminated portion of the moon is getting smaller.

There are two types of waning moons:

* Waning gibbous: The moon is more than half illuminated, but getting smaller each night.

* Waning crescent: The moon is less than half illuminated, and the illuminated portion is a thin crescent shape.

Let me know if you have any other questions about the moon!