The Anglo-Saxons, like most societies, knew that from midsummer day onwards, the sun rises slightly further south on the horizon each day, and that it takes 365 days before it returns to its most northerly position and repeats its cycle. This is called a year, or gear in Old English.
They also knew that in a year, the moon went through twelve complete phases, mysteriously changing shape each night until a ‘new moon’ appeared. Each month, or monath in old English, lasts about 29 days.
Annoyingly, there were always a few days left after twelve months (12×29=348) before the year was finished. The solution was to insert an extra month ‘æfterra līða’ every two or three years.
The Roman calendar had been constantly stretched and squeezed to fit the year until no single month actually matched the phases of the moon. This was the system that the Christian missionaries brought to England from Rome in the 600’s. By the end of the Anglo-Saxon period, the Roman system was triumphant everywhere, and we still use it today.
There is some disagreement about the meanings of the Anglo-Saxon month-names. Gēola is the same word as ‘Yule’, and may also have something to do with the ‘wheel’ of the year. Sol is something of a puzzle. Easter is linked with the word ‘east’, where the sun rises on the spring equinox. Hrēð and hlȳda may be gods or goddesses. Ðrīemilcemōnað may suggest that cows could be milked three times a day during this month, while līða may be an archaic word for month. Hālig means ‘holy’, and winterfyllēð could be the first winter moon. Blōtmōnað means ‘bloodmonth’, and may recall the month of sacrifices, or winter slaughtering of animals.