When the Moon is near its far point it is too small to cover the Sun, and a total eclipse becomes a ring of fire instead.

The Moon's apparent size varies by about 14% between perigee and apogee, and the Sun's by 3% over the year. For roughly a third of the cycle the Moon simply is not big enough, so the shadow's point falls short of the ground and everyone on the centre line sees an annulus. Annular eclipses are slightly more common than total ones, and much less impressive.