Magnitude of eclipse

This measure is strictly a ratio of diameters and should not be confused with the covered fraction of the apparent area (disk) of the eclipsed body.

As the magnitude of eclipse is less than one, the disk of the Moon cannot completely cover the Sun.

When the centers of the two disks are sufficiently aligned, a ring of sunlight remains visible around the Moon.

This is called an annular eclipse, from Latin annulus, meaning "ring".

The path of totality (i.e. of the travelling shadow of the Moon cutting off all direct sunlight from reaching the Earth's surface) is a relatively narrow strip, at most a few hundreds of kilometers across.