Some Facts about Eclipses

Updated February 21, 2017 | Factmonster Staff
Source: U.S. Naval Observatory and NASA/Goddard Space Flight Center

Anaxagoras, in the 5th century B.C., is credited as the first to figure out the true cause of a lunar eclipse, but his explanation neither reached nor convinced centuries of humanity, the majority of whom would have trembled with fear and trepidation as they watched the Moon turn the color of blood. For generations, an eclipse of the Moon foretold of no good.

Lunar eclipses do not occur as frequently as total solar eclipses, but they are visible from anywhere on the side of Earth facing the Moon during the evening. A total solar eclipse can only be seen from a narrow band about a hundred miles wide at most, and while up to seven of these a year are not unusual, they frequently occur over the most inaccessible regions on the planet.

The Sun can be viewed safely with the naked eye only during the few brief seconds or minutes of a total solar eclipse. Partial eclipses, annular eclipses, and partial phases of total eclipses are never safe to watch without taking special precautions. Even when 99% of the Sun's surface is obscured during the partial phases of a total eclipse, the remaining photospheric crescent is intensely bright and cannot be viewed safely without eye protection. Failure to use appropriate filtration may result in permanent eye damage or blindness.

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