Because the earth relies on the light from the sun. Only half of the planet can be lit at any time - due to the fact that light travels in straight lines.
This is what causes the so-called "phases" of the moon: although fully half of the moon is lighted, we can only see part of the lighted part. A person on earth hardly ever sees all of the lighted side of the moon. When he does, he calls the sight a "full moon."
A full Moon.
The lighted side of the Moon seen from Earth is the same during a full moon. At this phase, the Earth is positioned between the Sun and the Moon, allowing us to see the entire illuminated portion of the Moon's surface. This alignment results in the Moon appearing fully round and bright in the night sky.
the lighted half is facing towards the sun not the earth
Not exactly. The lighted side of the moon as seen from Earth is that part that is not shadowed by the Earth.
At any moment, 50% of the earth is lighted by the direct rays of the sun,and the other 50% of the earth is not.Over the course of a year, every point on earth is lighted by the direct raysof the sun for exactly 50% of the time, and not lighted by the direct rays ofthe sun for the other 50% of the time.There is no place on earth that is always lighted by the direct rays of the sun, andthere is no place on earth that is never lighted by the direct rays of the sun.Has the questioner ever noticed it getting dark outside his home ???
50%
The moon is in its waning phase when less and less of the side facing the earth is lighted. This phase occurs after the full moon and leads up to the new moon when the side facing the earth is completely dark.
new moon
Who really cares
new moon
crescent moon