TheSun beads

Baily's beads

As the moon "grazes" by the Sun during a solar eclipse, the rugged lunar limb topography allows beads of sunlight to shine through in some places, and not in others. This effect is called Baily's beads in honor of Francis Baily who first provided an exact explanation of the phenomenon in 1836.[1]

Lunar topography has considerable relief because of the presence of mountains, craters, valleys and other topographical features. The irregularities of the lunar limb profile (the "edge" of the Moon, as seen from a distance) are known accurately from observations of grazing occultations of stars. Astronomers thus have a fairly good idea which mountains and valleys will cause the beads to appear in advance of the eclipse. While Baily's beads are seen briefly for a few seconds at the center of the eclipse path, their duration is maximized near the edges of the path of the umbra, reaching 1–2 minutes.

The Baily's beads phenomenon is seen during the credit opening sequence of the NBC TV show Heroes.

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  1. Littmann, Mark; Willcox, Ken; Espenak, Fred (1999). Totality - Eclipses of the Sun, Oxford University press. pp. 65–66. ISBN 0195131797. 
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bn:বেইলি'র হার bg:Броеница на Бейлиis:Perlur Bailys pl:Perły Baily'egosk:Bailyho perly sl:Bailyjevi biseri sv:Bailys pärlor