What a total solar eclipse is
A total solar eclipse occurs when the Moon passes directly between Earth and the Sun and completely covers the Sun's bright surface for observers inside the Moon's umbral shadow. The alignment is temporary, and the shadow crosses only a narrow strip of Earth.
Outside that strip, observers may see a partial eclipse. The sky can darken and the Sun may look like a crescent, but the experience is different from totality because even a small visible portion of the Sun remains intensely bright.
Why totality feels so dramatic
During totality, the bright solar surface is hidden and the Sun's outer atmosphere, called the corona, becomes visible. The horizon can glow in every direction, temperatures may drop briefly and bright stars or planets can appear. Animals sometimes react to the sudden change in light, although the exact response varies by species and location.
The dramatic darkness is caused by the Moon's shadow, not by the Sun becoming weaker. The event ends as soon as the Moon moves far enough for direct sunlight to return.
The most important safety rule
Never look directly at the uneclipsed or partially eclipsed Sun without certified solar-viewing protection. Ordinary sunglasses, cameras, binoculars and telescopes do not provide enough protection. Optical devices can concentrate sunlight and cause serious eye injury.
