The Full Moon . ... Credit Copyright: Lick Observatory Explanation: Earth has one moon. ... The Moon glows by light it reflects from the Sun and is frequently the brightest object in the night sky. ... The above-pictured Full Moon occurs when the Moon is nearly opposite to the Sun in its orbit. The Moon's diameter is about 1/4 that of the Earth , and from the Earth's surface appears to have almost exactly the same angular size as the Sun. ... NASA Web Site Statements, Warnings, and Disclaimers . ...