An almanac (also spelled almanack and almanach) is an annual publication that includes information such as weather forecasts, farmers' planting dates, tide tables, and tabular information often arranged according to the calendar. Astronomical data and various statistics are found in almanacs, such as the times of the rising and setting of the sun and moon, eclipses, hours of full tide, church festivals, and so on.
The etymology of the word is unclear, but there are several theories:
The reason why the proposed Arabic word is speculatively spelled al-manākh is that the spelling occurred as "almanach", as well as almanac (and Roger Bacon used both spellings). The earliest use of the word was in the context of astronomy calendars.
The prestige of the Tables of Toledo and other medieval Arabic astronomy works at the time of the word's emergence in the West, together with the absence of the word in Arabic, suggest it may have been invented in the West and is pseudo-Arabic. At that time in the West, it would have been prestigious to attach an Arabic appellation to a set of astronomical tables. Also around that time, prompted by that motive, the Latin writer Pseudo-Geber wrote under an Arabic pseudonym. (The later alchemy word alkahest is known to be pseudo-Arabic.)
An almanac is a text listing a set of events forthcoming in the next year. A calendar, which is a system for time keeping, in written form is usually produced as a most simple almanac: it includes additional information about the day of the week on which a particular day falls, major holidays, the phases of the moon etc. The set of events noted in an almanac are selected in view of a more or less specific group of readers e.g. farmers, sailors, astronomers or others.
The earlier texts considered to be almanacs have been found in the Near East, dating back to the middle of the second millennium BC. They have been called generally hemerologies, from the Greek hēmerā, meaning "day". Among them is the so-called Babylonian Almanac, which lists favorable and unfavorable days with advice on what to do on each of them. Successive variants and versions aimed at different readership have been found. Egyptians lists for good and bad moments, three times each day, have also been found. Many of these prognostics were connected with celestial events. The flooding of the Nile valley, a most important event in ancient Egypt, was expected to occur at the summer solstice but as the civil calendar had exactly 365 days, over the centuries the date was drifting in the calendar. The first heliacal rising of Sirius was used for its prediction and this practice, the observation of some star and its connecting to some event apparently spread.