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.
With interest rapidly building for the upcoming total solar eclipse in the USA on August 21, 2017, I became curious about the rarity of total eclipses in America. The very first total eclipse I witnessed was on March 7, 1970.