Grahanam refers to the phenomenon of an eclipse, which occurs when one celestial body moves into the shadow of another. This can happen with the Sun, Moon, and Earth. There are two main types of eclipses: solar eclipses, where the Moon passes between the Earth and the Sun, and lunar eclipses, where the Earth comes between the Sun and the Moon. Eclipses can be partial, total, or annular, depending on the alignment of the three bodies. They have been observed and studied for centuries, often holding cultural and scientific significance in various societies. Understanding Grahanam helps astronomers predict these events and their effects on the Earth.