Very slightly more than 50%.
the sun
1 half
rays of light from the sun
the answer is the sun
it comes from the sun. The sunlight reflects off of the moons surface, and goes to your eyes.
The Sun has no moons. Moons orbit Planets > Planets orbit the Sun.
Uneven heating from the sun.
...is always experiencing its day time, and is always fully lit unless it is eclipsed by its planet or another moon.I don't believe that there are any moons in our solar system that are tidally locked with the sun. In other words, moons do not have faces that are permanently oriented toward the sun.
There are no moons on the sun.
50% of its surface at all times. But which 50% keeps changing.
The moon is ALWAYS 50% (+/-) illuminated. Though we only see all of the half lit side when the moon is opposite the sun (Full Moon).
They reflect light from the sun back to observers on earth, unlike the stars, which emit their own light. Everything in our solar system is `lit up` by our sun, which emits light. The planets and moons (along with comets and other objects) don't emit light themselves, but are illuminated by the sun.