The Calendar Essay Research Paper Kara Byers

The Calendar Essay, Research Paper Kara Byers 1CHtutor: Dr. Gerard McCartan Our View of the Universe ?It took several thousand years to establish a satisfactory calendar. Even in this century not all the countries in Europe kept the same calendar. Why was it so difficult? Do we really need an accurate means of recording civil time? Astronomy originated earlier in human history than the other natural sciences. In the earliest civilisations, the divine or occult was used to explain the movement of the stars and the Sun: the Aztecs, for example, believed that the Sun had to be nourished with a sacrifice of blood and a beating human heart, or else it would vanish. In those dark days there was no conflict between science and religion: a priest, magician or shaman would jealously

guard scientific knowledge of the seasons and calendar. Knowledge, regarded as a sign of divine work in the world, conferred immense status on priests in their community, because they were able to foretell the future with some success. Astronomy meant power over people. It guided Man through the seasons, showing when to plough, to harvest or to move herds. Religious and sacrificial acts also had to be performed on specific occasions, for example, to coincide with the phases of the Moon or solar solstices. Astronomy also helped to guide the traveller. With the rise of the calendar, human activities could be linked more accurately with the seasons and thus better co-ordinated. Three of the periods used in calendars ? days, months and years ? are based on astronomical cycles that

have the greatest bearing on human life. The very earliest calendars relied on the Moon, which not only rose and set but changed its shape over a period of around a month that is convenient for describing the seasons. Later calendars evolved to take account of the Sun?s annual cycles. The ancient Egyptians are credited with one of the most advanced solar calendars of ancient times. Astronomy was their key to predicting the great annual event, the inundation of the Nile which coincided with the pre-dawn appearance on the eastern horizon of Sothis (Sirius), the brightest star in the sky. To the ancient Egyptians the event was so important that they dubbed the rising of Sirius the ?Opener of the Year?, and the calendar was arranged around this event. Many ancient calendars had

twelve months based on the average period of around thirty days between new moons, making a year that fell short of the solar year and had to be extended: the original Egyptian calendar had twelve months and, being linked to the Moon?s thirty-day cycle, produced a three hundred and sixty day year. Later it had additional five days added at the end of the year to keep the lunar month and the solar-based seasons co-ordinated and thus the calendar in step with the ?Opener of the Year?. We thank the Egyptians for the twenty-four hour day, running from sunrise to sunrise. A twelve-hour cycle fitted the movement of the stars across the sky, with an hour marking out the time between each star, or group of stars, rising on the eastern horizon. In this way, the twelve hour night evolved

and, probably for the sake of symmetry, a twelve hour day. The Egyptians measured the passing daylight hours with the water clocks, where the flow of time was measured by water trickling through a hole in a stone vessel, and with sundials and shadow clocks, where a sweeping shadow showed the passing hours. The last two furnished merely ?temporal hours?; they were not equal and varied according to the seasons. In Japan, temporal hours were still in use in the nineteenth century and mechanical clocks were adapted accordingly, but in Europe, the day was carved in to twenty-four equal hours in the fourteenth century, when towns introduced mechanical clocks. Our own calendar is derived from that employed by the Romans. They used a lunar month, squeezing in a month every so often to