On the Move!

Although seemingly far away from us on Earth's surface, there is a lot to observe and explore in the sky! Just look up during the daytime and nighttime and you’ll see the shining Sun, the bright Moon and hundreds of twinkling stars. As the Earth rotates on its axis and revolves around the Sun, the Moon too is on the move, orbiting the Earth! When these celestial bodies line up just so, an eclipse can occur. An eclipse is an event that takes place when the light from one celestial body is blocked by the passage of another celestial body between it and the viewer or between it and its source of illumination. At times, the Earth can move in between a Full Moon and the Sun, thus blocking the sunlight that is normally reflected off of the Moon’s surface. Due to this blockage, the Earth’s shadow falls on the Moon, causing a lunar eclipse. In this lesson, students will develop and use models to explain how lunar eclipses occur within the Sun-Earth-Moon system.