Sure we all have an intuitive idea of what a calendar is - a way to mark time, but how many of us take the time to consider what this really means? What is time? How do we know when an event has happened or will happen? In the broadest sense, in order to figure out time, we need to be aware of not just our immediate environment, but our planet, the sunrise and sunsets, the passage of the seasons. Our ancestors generally looked up to the heavens, made some awfully clever observations, and created a system of predictability through their observations. Not all societies based their observations on the sun - most did, but not all. The ancient Islamic society fashioned their predictions on the regular phases of the moon and only the moon. The Jewish calendar is an interesting hybrid of both solar and lunar observations. The ancient Persian is strictly solar, and is considered so accurate that it will lose 1 day in 3.8 million years. Now, that's predictability. What does a calendar tell about a culture? It tells a lot, actually. A culture whose calendar is based on the passage of the sun is a culture that is growing crops: they are agrarian based. When the vikings settled ancient Iceland, an accurate calendar was extremely important to them, for it not only told them when to optimally plant their crops for the short Icelandic growing season, but it was required as through a social need as well. For two 2 weeks once a year, Icelandic chieftains gathered from around Iceland and met in an assembly called the Althing. Traversing the rough Icelandic terrain was made bearable if everyone was arriving at the event at the same time. What assisted in determining when the next year began was the knowledge of where the sun was in the sky. Effectively, the earth passes through 4 distinct phases in its orbit around the sun. Each of these phases is marked at a specific measurable astronomical point - the solstice/equinox. (Spring Equinox, Summer Solstice, Autumn Equinox, Winter Solstice). So, armed with knowledge about the heavens, and knowing how to predict when the next astronomical phase was going to occur was a long way in producing a predictable schedule for the next meeting. A culture that is lunar based is more nomadic. The Islamic calendar runs from New Moon to New Moon. No matter what time of the year, one can always look at sky, and see the moon and judge the calendar date based on the moon phase. A New Moon means the month has just started, while a Full Moon means that the month is half over. This kind of instant calculation was essential to travellers needing to determine when they much stop their travels to observe the fasting season of Ramadan which lasted for an entire Islamic month (lunar cycle). Here on our Calendar Articles, we discuss such items as the Gregorian Reform, to How we figured out the Viking Calendar. We've lots of articles planned, too. So if you don't see what you want now, please come back later.