An eclipse of the Sun happens when the New Moon moves between the Sun
and Earth, blocking out the Sun's rays and casting a shadow on parts of Earth.
The Moon's shadow is not big enough to engulf the entire planet, so the
shadow is always limited to a certain area (see map illustrations below). This
area changes during the course of the eclipse because the Moon and Earth
are in constant motion: Earth continuously rotates around its axis while it orbits
the Sun, and the Moon orbits Earth. This is why solar eclipses seem to travel
from one place to another