The eclipse can refer to either a solar or lunar eclipse. A solar eclipse occurs when the Moon passes between the Sun and Earth, casting the Moons shadow on Earth, and can only happen during a New Moon. On the other hand, a lunar eclipse happens when Earth positions itself between the Sun and the Moon, casting a shadow across the lunar surface, and can only occur during a full Moon. In summary, the cause of a solar eclipse is the Moon blocking the Suns light from reaching Earth, while the cause of a lunar eclipse is Earth blocking sunlight from reaching the Moon and creating a shadow across the lunar surface.