During a solar eclipse, a group of students is observing the event from a location where they can see the Diamond Ring effect. They notice that just before totality, the sunlight creates a bright spot on the edge of the Moon. Why does this phenomenon occur, and what does it tell us about the nature of solar eclipses?

The Diamond Ring effect happens because the Moon is not a perfectly smooth disk; its surface has mountains and valleys. Just before the Moon’s silhouette completely covers the Sun, the last rays of sunlight can still shine through a deep lunar valley while the rest of the Sun is hidden by the Moon’s rim, producing a bright “ring. ” This bright spot is the Sun’s light that has slipped past the lunar topography, showing that the eclipse is almost total. Seeing the ring confirms the precise alignment of the Sun, Moon, and Earth, and it demonstrates that the eclipse is caused by the Moon’s shadow sweeping across the Earth’s surface. Thus, the phenomenon is a clear visual proof of the geometry and timing that make a total solar eclipse possible.