Partial Versus Total Eclipse Safety
It is never safe to look directly at a solar eclipse in progress. Even though half the sun is covered, it does not mean that it is half as dangerous to look up! The UV rays emitted from the sun are still equally as dangerous as it would be to look at the sun directly. In order to ensure eye safety and protection of the retina, one must look at a partial eclipse via safety glasses or projecting the images via a pinhole camera, until the eclipse reaches totality.
However, during a total eclipse, during totality- or, when the sun is completely blocked by the moon (which will only happen in a narrow portion of the eclipse path) - is safe to look at because the moon effectively blocks the sun’s rays.
The safety of watching a total eclipse is only for a brief minute, and then the rays become dangerous to the eye. While it is technically safe to look at the exact moment of totality, it is recommended not to. The sun can become dangerous in milliseconds, even during totality. Better safe than sorry: do not look directly without protection!