An annular eclipse occurs when the Moon passes in front of the Sun but appears slightly smaller, leaving a bright ring of sunlight around its dark silhouette. That ring is called the annulus, giving the eclipse its name.
The Moon's orbit around Earth is elliptical, so its distance varies. When the Moon is farther away, it appears smaller in the sky. If it crosses the Sun's face at that time, its apparent diameter is not large enough to cover the entire solar disk. Observers along the eclipse path see the distinctive “ring of fire.”
An annular eclipse is a type of solar eclipse, but it is not the same as a total eclipse. During totality, the Moon completely covers the visible surface of the Sun. A partial eclipse occurs when the Moon covers only part of the Sun, while a hybrid eclipse can appear total from some locations and annular from others.
Even during an annular eclipse, the uncovered Sun is dangerously bright. Special-purpose solar viewing glasses are required; ordinary sunglasses do not provide adequate protection.