When the New Moon passes between the Sun and Earth, obscuring the Sun's rays and casting a shadow over a portion of the planet, this is called an eclipse of the Sun.
As can be seen in the map illustrations below, the Moon's shadow is never large enough to cover the planet as a whole. Because the Moon and Earth are always moving, this area changes during the eclipse: During its orbit around the Sun, Earth and the Moon both rotate in a constant circle. Solar eclipses appear to move from one location to another because of this.
