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Eclipse Glossary

An astronomical alignment in which one object covers another, blocking it from view. An eclipse can be total, in which the eclipsed object is completely obscured, or partial, in which only a portion of the eclipsed object is blocked.
Solar Eclipse
An alignment in which the Moon passes directly between Earth and the Sun, fully or partially obscuring the Sun. During a total eclipse, the Moon completely covers the solar disk, briefly turning day to night. During a partial eclipse, some of the Sun remains in view.

The Moon casts its shadow on Earth's surface during a total solar eclipse.The Moon casts its shadow on Earth's surface during a total solar eclipse. [Tim Jones]
The phase of a solar eclipse in which the Sun is completely obscured. It occurs along a narrow path (usually no more than 100 miles wide), and lasts for no more than a few minutes. Totality lasts longest along the center line of the eclipse path. During totality, the Sun’s outer atmosphere, the corona, is visible around the intervening Moon. It is safe to view the totally eclipsed Sun without eye protection.
Diamond Ring
The Diamond Ring Effect [kubotake/Wikipedia]The Diamond Ring Effect [kubotake/Wikipedia] In the moments just before or after the Moon fully covers the Sun, a ring of light encircles the Moon, with a bright “diamond” along its circumference. The diamond is the last flash of the Sun before it is fully obscured, or the first flash as it begins to emerge from totality. The remaining sliver of sunlight is too bright to view safely without eye protection.
Baily’s Beads
Francis BailyFrancis Baily These tiny beads of light around the Moon form as sunlight passes through valleys, canyons, and other indentations on the lunar surface. They are named for Francis Baily, who wrote a detailed description of the phenomenon after an eclipse in 1836.