Watching solar eclipse. Young boy using a special protective viewer to observe a solar eclipse. The Sun is seen reflected in the material covering his eyes. This material is designed to block most of the light from the Sun. Observing the Sun without any protection can damage the eyes and cause blindness. Solar eclipses occur when the Moon passes across the Sun as seen from Earth. It only occurs at New Moon, and is most commonly a partial eclipse. Sometimes, usually less than once a year, a total solar eclipse takes place. This happens when the Moon passes directly in front of the Sun, and, for a few minutes, the corona, the Sun's atmosphere, becomes visible.