One-Third of a Second

The rather enigmatic title of this entry refers to the accuracy with which the Babylonians were able to predict the length of lunation, the average length of a lunar month. As far back as the fourth century BC, Babylonian astronomers had not only calculated the Metonic calendar – which enabled them to predict lunar and solar eclipses – they had also accounted for the changing speed of the Moon as it orbits Earth.

As you may be aware, lunar months vary in length, which is due to the fact that the Moon’s orbit is elliptical, making its speed increase as it comes closer to Earth (in the same way that your own radial velocity when spinning on a chair can be increased by bringing your arms closer to your body). Many early cultures, relying upon an understanding of the phases of the Moon in order to plan their religious and cultural observances, were happy to settle upon a two-stage model of the Moon’s orbit, accounting for its maximum and minimum orbital speeds. While this was perfectly accurate enough for most uses, the Babylonians were rarely satisfied with ‘accurate enough’.

The astronomer Kidinnu – a truly remarkable individual – replaced this original system with a more precise calculation that took the variable speed into account, and, in the fourth century, had an error of only one-third of a second. Remember, of course, that until Kepler’s laws of planetary motion were written in the early seventeenth century AD, there was no model for establishing this information, and that the Baylonians had no way of measuring the distance from the Earth to the Moon.

In order to understand just how important this was to the Babylonians, we must understand their cultural attachment to the heavens. Like other cultures of the era, they associated their gods with the Sun, Moon and the five known planets (Mercury – Nabu; Venus – Ishtar; Mars – Nergal; Jupiter – Marduk; Saturn – Ninurta), which, being gods, made them responsible for much that happened in Babylonian society. As such, a Babylonian astronomer’s duty was to maintain a ‘diary’ to record not just the details of the sky, but also events upon the Earth.

For example, their diary included information such as: the times of sunrise and sunset; the positions of the moon and planets relative to the constellations; the weather – even rainbows were recorded; local news of importance such as fires and thefts; more significant news, such as conquests or victories in battle; the height of the water in the Euphrates; and even the relative value of the shekel in the markets.

The Babylonians did not merely believe that their gods resided in the stars, but also that they were responsible for the tiniest minutiae of common life. When the stars are the reflection of the gods’ will, and that this influences society on such fundamental levels, one-third of a second is, indeed, an appropriate margin of error.

How the Mayans Observed their Stars

It is commonly believed that accurate astronomical observations were close to impossible before the advent of the telescope. Certainly, Western societies struggled to accurately measure or predict astronomical events before that invention (barring some ingenious work in observing our own solar system), and its advancement to today’s standards has allowed discoveries hitherto impossible. Regardless of our own approach to astronomy, pre-Columbian Mayan civilisation developed a remarkable array of astronomical measurement devices, utterly without the use of a single traditional lens for magnification.

El Caracol, at Chichen Itza, for instance, is a Mayan observatory; built on a raised platform, it is a circular structure with a spiral staircase within, leading to the observatory chamber. This chamber was built with small windows designed for astronomical observation. These windows were so placed as to catch the passage of the Sun, Moon and Venus at various stages in their passage across the sky. By placing pools of water beneath each window, they could then be used to accurately observe which stars were in the same relative locations in the sky on specific dates. At school, you may have made a similar device using a hole in a piece of paper to observe a solar eclipse or the transit of Mercury across the sun.

Through extended observation of the positions of stars, the relative positions of the Sun and the Moon, and so on, the Mayans were able to accurately predict such events as solar and lunar eclipses, as well as auspicious dates within their religious framework that relied upon the constellations themselves.

In addition to such advanced structures, even their simple pyramids were designed to cast shadows or to illuminate brilliantly at certain times of year, in accordance with their religious observances. El Castillo, for example, is primarily noted for the fact that the total number of steps is 365, but, during the equinoxes, the setting Sun casts a serpentine shadows that climbs the northern steps of the pyramid, matching tales from their rich and fascinating cosmogony.

Stars and their Pyramids

To begin, I thought I should discuss why I have named my blog ‘Stars and their Pyramids’.

In brief, it is a reference to what is called the ‘Orion Correlation Theory’ (or OCT). Rather than describe it in full here, I recommend instead that you read the Wikipedia article, which provides a sound overview. In brief, it refers to the flawed theory that pyramids across the world were placed to precisely match the stars in Orion’s belt and other constellations.

It is my position that this is, in its broadest terms, fascinating, if flawed. It is a testament to the wonder of mankind, and to the poetic creativity with which we approach problems, that this theory even exists. I am not a man constrained to the discussion of scientific facts, but a man intrigued by what we as humans can conjure from symbols of the past.