The document discusses lunar and solar eclipses. It explains that lunar eclipses occur when the Earth passes between the sun and moon, casting its shadow on the moon. Solar eclipses occur when the moon passes between the Earth and sun, casting its shadow on parts of Earth. Eclipses only occur when the sun, Earth, and moon are aligned on the same plane. The document provides details on the conditions required to see each type of eclipse and diagrams demonstrating the geometry of lunar and solar eclipses.