Exactly 50% of the moon is illuminated by the sun at every instant of time (except during a lunar eclipse).
From our vantage point on earth, the amount of the illuminated half that we can see at any time changes
during the month.
"First Quarter" means the first quarter of the moon's entire cycle of phases ... about 7.4 days after the
"New Moon". At that time, we see half of the illuminated part of the moon ... you'd call it a "half moon".
A "gibbous" Moon has between 51% and 99% of the illuminated side of the Moon visible from Earth. Just to be precise; the Moon is always 50% illuminated. The Moon is a rocky ball, half in sunlight and half in darkness. As the Moon orbits the Earth, the same face of the Moon is always visible. From the Earth, we see "phases" of the Moon as the Moon orbits the Earth. At the new moon phase, the illuminated half of the Moon is the "far side" of the Moon; at the full, the illuminated half is the "near side".
You will never see a new moon during sunset because, at this phase, the moon is positioned between the Earth and the Sun. This alignment means the illuminated side of the moon is facing away from Earth, making it essentially invisible in the night sky. Hence, the new moon is not visible at sunset or at any time during the night.
In the "waxing" phases, the amount of the Moon illuminated by the Sun is increasing. When the Moon is fully illuminated it is "full", and after that it begins to "wane" or decrease in brightness. The the Moon is new, and is invisible, and the endless cycle begins again.
"Gibbous" . . . less than full but more than half illuminated.
"First Quarter" is the phase when the moon appears half-illuminated, and rises and sets roughly 6 hours (1/4 day) after the sun.
No. Only half of the moon is illuminated at any one time. During a full moon, the half facing Earth is fully illuminated.
The percentage of the moon that is illuminated varies during different lunar phases. During a full moon, 100% of the moon is illuminated, while during a new moon, 0% is illuminated. The waxing and waning phases fall somewhere in between, with values from 1% to 99% illuminated.
If you live in the Northern Hemisphere, the left side of the moon is illuminated. If you live in the Southern Hemisphere, the right side of the moon is illuminated. Regardless of hemisphere, the western half of the moon is illuminated during the waning moon phases.
During a last quarter moon, the moon appears half-illuminated in the sky. This phase marks the halfway point between a full moon and a new moon. The illuminated portion of the moon is decreasing, leading up to the new moon phase.
50%
The waxing phase of the moon is the period of time between new moon and full moon, where the size of the illuminated portion of the moon is increasing. The waning phase of the moon is the period of time between full moon and new moon, where the size of the illuminated portion of the moon is decreasing.
The Moon is not visible at the new moon phase. At the first quarter, it is "waxing" - the illuminated portion is increasing. At the full, the illuminated portion of the Moon is 100%, and it is finished waxing and is about to begin "waning", when the illuminated part is decreasing. At the 3rd quarter, it is waning.
After a full moon, the illuminated portion of the moon gradually decreases as it moves toward the last quarter phase. This period is known as the waning phase, during which less of the moon's surface is lit by the sun. The illuminated half decreases until it reaches the new moon phase, where the moon is not visible from Earth.
You will see most of the moon's surface during the full moon phase when the entire illuminated side of the moon is facing Earth.
There are two separate things that need to be addressed. One is the surface area of the Moon. The other is the surface area of the NEAR SIDE of the Moon. As a sphere in space, the Moon is always 50% illuminated, except during lunar eclipses. The phases of the Moon measure what percentage of the NEAR SIDE of the Moon is illuminated. At the new moon, none of the near side is lit up; at the full moon, 100% of the near side is illuminated.
During a full moon, the side of the moon facing Earth is fully illuminated by the sun, making it appear as a complete circle from our perspective. The side not facing Earth is in shadow, causing us to only see the illuminated side during a full moon.
One week after the full moon, the moon is in its third quarter phase. During this phase, the left half of the moon appears illuminated when viewed from the Northern Hemisphere, while the right half appears illuminated from the Southern Hemisphere. This is because the sunlight is shining on the opposite side of the moon compared to the full moon phase.