Most of the time the Moon passes above or below the Sun, and nothing spectacular occurs. However, occasionally the Moon passes directly in front of the Sun and blocks its light.
And, it this particular case, the Moon is near its apogee (the point furthest in its orbit from Earth).
When this happens and it passes in front of the Sun, it will not completely cover the Sun, and we get this “ring of fire” effect.
At the peak of this solar eclipse about 94% of the sunlight from the Sun will be blocked by the Moon.
Only the outer parts of the sun will be visible, which will produce a ring of visible light around its circumference.
Page two concludes.