Moon Phase Diagram: First and Last Quarter Explained #3604638 (License: Personal Use)

This graphic illustrates a quarter moon phase-either first or last quarter-where the Sun illuminates precisely 50% of the lunar disk as viewed from Earth. The left side is sunlit in a pale yellow hue with visible crater markings, while the right side remains in deep shadow, emphasizing the terminator line and surface topography. The design uses flat vector styling for clarity and educational use.

Commonly used in astronomy education, science blogs, and lunar calendar apps to explain monthly lunar cycles; targets users seeking basic moon phase understanding or visual aids for teaching.