A substance is anhydrous if it contains no water, for example, salts lacking their water of crystallisation. The way of achieving the anhydrous form differs from one substance to another.
A partial solar eclipse at its peak at 3:37 p.m. in Mesa on Oct. 23, 2014. The eclipse was visible over most of North America and covered 44 percent of the Arizona sun. Michael Chow/The Republic.
Bottom line: Links to everything you need to know about the total solar eclipse of August 21, 2017. Itâll be the first total solar eclipse visible from the U.S. since 1991 (seen only from part of Hawaii), and first visible from contiguous U.S. since 1979.