Question

Question #ec6d0

Answer 1

Any spherical body which gets sun light will be illuminated 50% of its surface.

Explanation:

as Moon goes round the earth in 27 days and 8 hours we see only part of this 50%.
The attached picture shows how moon looks different for earth observers in outer portion of moon where as inner portion shoes it is always 50% illumined.
Picture credit Astro ohio state edu.