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.
A Total Solar Eclipse can last for several hours. Totality can range from a few seconds to 7 and a half minutes. The longest Total Solar Eclipse of the 21st century took place on July 22, 2009 when the totality lasted 6 mins and 39 secs. Total Solar Eclipses are rare, and only happen (every one or two to three years) when: 1  There is a New Moon. 2  The Moon is near a lunar node.