... becoming smaller as time passes.
A waning Moon is one were it appears to be becoming smaller. From a full round full moon, to a last gibbous moon, to last quarter, to last crescent moon, the an New Moon. The corresponding increasing Moon is named a WAXING Moon.
The term used to describe the decrease in the visible portion of the moon is "waning." This occurs as the moon transitions from a full moon to a new moon phase.
When the illuminated portion is decreasing from one night to the next, the moon is in its 'waning' phases.
When the visible bright part of the Moon is increasing in size, the term "waxing" is used. When the visible part of the Moon is less and less illuminated each night, the term "waning" applies.
When less and less of the moon is visible, it is transitioning from a full moon to a new moon. This phase is known as the waning gibbous phase, followed by the third quarter, waning crescent, and finally the new moon.
Moon Phases:Right half visible - First QuarterRight Crescent visible - Waxing CrescentNot Visible - New MoonLeft Crescent Visible - Waning CrescentLeft Half visible - Third QuarterLeft mostly visible - Waning GibbousAll visible - Full moonRight mostly visible - Waxing Gibbous
Moon Phases:Right half visible - First QuarterRight Crescent visible - Waxing CrescentNot Visible - New MoonLeft Crescent Visible - Waning CrescentLeft Half visible - Third QuarterLeft mostly visible - Waning GibbousAll visible - Full moonRight mostly visible - Waxing Gibbous
As a waning moon is getting smaller, a waning gibbous moon is losing light.
The waning crescent moon is often visible above the western horizon a couple of hours before sunrise. Its shape will be more pronounced as it approaches the new moon phase.
A waning moon
Each month the moon goes through phases from new moon to full moon. The last visible slice before a new moon is called a waning crescent.
Getting larger is WAXING. Getting smaller is WANING..