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.
It's been more than three decades since the total solar eclipse of Feb. 26, 1979, which crossed through Washington, Oregon, Idaho, Montana and North Dakota, before heading north to Canada, according to NASA. That's the last time the contiguous U.S. has seen a total solar eclipse, until the one on Aug. 21, 2017.