An Etymological Dictionary of Astronomy and Astrophysics

The necessary precautions that must be taken in order to avoid damaging the eyes when watching a → solar eclipse. The only time that the Sun can be viewed safely with the naked eye is during a → total eclipse, when the Moon completely covers the disk of the Sun. It is never safe to look at a → partial eclipse or → annular eclipse, or the partial phases of a total solar eclipse, without the proper equipment and techniques. Even when 99% of the Sun’s surface (the → photosphere) is obscured during the partial phases of a solar eclipse, the remaining crescent Sun is still intense enough to cause permanent retinal damage, especially when viewed through binoculars or other optical aids (F. Espenak, NASA).

Etymology (EN): → eye; safety, M.E. sauvete, from O.Fr. salvetet, from M.L. salvitatem “safety,” from L. salvus, cognate with Pers. har “all, each, every,” → holo-.

Etymology (PE): Gazand “damage, injury,” Mid.Pers. wizend, ultimately from *ui-jan-, from *ui- “apart, away from,” → expand, + *jan- “to beat, strike,” cf. Pers. zan-, zadan “to beat, strike,” → beat; cašm, → eye
Zilegi, → security.