Welcome to Ramadan.

What does a month of religious observations, in what is very much a minority religion in America, have to do with a blog which is largely about science fiction? A great deal, as it turns out.

Beyond simple humanity, an interest in those whose view of the universe is not identical to most Americans, and a sense of fairness that impels us to look at Islam as a full fledged way of life, there are also non-religious, even scientific aspects of this season. When you realize that Ramadan cycles around the year, it becomes apparent that there is a lot of astronomy behind this month of observance.

So first, what is a month?

A month is the time it takes for the moon to orbit once around the Earth – oh, if it were only that simple.

For a start, science recognizes five kinds of months. A sidereal month of 27.3 days and the tropical month, also of 27.3 days, refer to one passage past a “fixed star” and an equinox point respectively. An anomalistic month is the time from perigee to perigee, 27.5 days, and a draconic month is the time from a node to the same node, about 27.2 days. A node is a point where the plane of the moon’s orbit crosses the plane of the Earth’s orbit.

Astronomy was not one of my fields of study. Every time I look up something like this my head spins, but no wonder. Everything in astronomy consists of measuring moving objects in reference to other moving objects.

The synodic (aka normal) month is the only one non-astronomers worry about. At 29 and a half days, it is the time it takes to go through one cycle of new to new moon. It is a little over two days longer than the others because it also includes chasing the Earth through roughly one twelfth of its orbit.

If that wasn’t complicated enough, none of the months come out in a even number of days and none of them divide evenly into the length of a year. If we were using a lunar calendar, as Muslims do in their religious life, our months would cycle around the calendar and only appear in the same season every (?) years. I didn’t give you a number there, because there are dozens of varieties of lunar calendar.

That works fine for religious observances, and it worked fine in the Arabian desert where the Islamic calendar got its start, but it doesn’t work in a globally connected world or in agricultural societies. You need to plant or harvest during the same month each year, and you need a common calendar to schedule happenings outside your area.

Non-Muslims who know anything about Ramadan, know that it is a month of fasting. It is more than that, and of course it doesn’t mean no one eats for a month. Fasting takes place during the daylight hours. A meal is taken just before sunrise, and another just after sunset, and fasting is not required of the ill, pregnant women, children below a certain age – there is a list, although it varies by sect.

In the mid-latitudes, when Ramadan falls during winter, the fasting hours are short; when it falls in summer, fasting if more arduous. There are special rules for those who live near the Arctic and Antarctic circles, otherwise they would have to fast nearly twenty four hours of each day when Ramadan falls in the land of the midnight sun.