SFC author Kassandra Radomkie's article, Telling Time with the Sun, Moon, and Stars, won 4th place in the Preditors & Editors Reader Poll 2008 for Best Nonfiction.
Telling Time With the Sun, Moon & Stars
By: Kassandra Radomski
Imagine your day without clocks and calendars. See the sun peeking through your windows? It’s time to get up. Notice the sky darkening? Almost time for bed. This is how people once lived—without knowing the time or the day.
When humans started farming, they needed ways to measure days and months to determine the right time to plant and harvest their crops. The ancient Egyptians discovered they could measure time and the passing of days with the sun, moon, and the stars.
Thousands of years ago people looked at the shadows cast by the sun to help them determine the approximate time of day. They recognized what is still true today: our bodies make long shadows early in the day, shorter shadows as the sun rises in the sky, and by mid-day our shadows nearly disappear. After mid-day, our shadows gradually grow longer again until the sun sets in the west. Around 3500 B.C. the ancient Egyptians started using obelisks (ob-uh-lisks), or tall stone structures, to cast shadows for measuring time. This way of measuring time was not very precise.
The ancient Egyptians marked the passing of days and months according to changes in the moon. They discovered that the eight different phases of the moon took about 29.5 days, which is about one month on our calendars today. Four moon cycles (or months) made up one season. Back then there were just three seasons in a year, rather than the four we know today.
The seasons corresponded not only with the moon, but also with the rising of the Nile River, which was the center of Egyptian life. The flooding of the Nile River was so significant that it marked the new year for the ancient Egyptians. Today we fear floods, but back then the Egyptians looked forward to the flood because it covered the land with a rich black soil that helped them grow their crops.
This first season of the year was called achet, or “inundation.” (The word inundation means to cover with a flood.) It began during what today is about mid-June and lasted until about mid-October. The next season, peret or “coming forth,” was when seeds were planted and crops were grown. This period lasted until about mid-February. The final season of the ancient Egyptians’ year, shemu or “harvest,” was when the crops were harvested. It lasted until about mid-June when the new year began again. The ancient Egyptians used the moon to help them determine the seasons, but the moon could not help them predict when the flooding of the Nile River and the beginning of the new year would occur.
Once again, the ancient Egyptians looked to the night sky. There they discovered one particular star that could help them. Sopdet, the brightest star in the sky, was no ordinary star. (This star was also known as the Dog Star or Sothis. Today we call it Sirius.) Egyptian priests discovered that the Nile flood began a few days after Sopdet appeared in the eastern sky right before sunrise.
The rising of Sopdet and the moon’s cycles were the basis for the Egyptian’s lunar calendar. Although the Egyptian lunar calendar began as long ago as 4236 B.C., even then it consisted of 365 days per year, just like today. Eventually the Egyptians used three different calendars, all of which used the sun, the moon, and the stars to mark time.
Although we rely on clocks and calendars today, we can still use the sun, moon, and the stars to help us tell time, just like the ancient Egyptians did. The next time you find yourself without a watch, try judging time by the length of your shadow. Or try determining the dates of the month by the phases of the moon. Sirius is brightest in the winter and early spring. Look for it north of the constellation Canis Major. Imagine your life without clocks or calendars—just the sun, moon, and the stars to mark the passing of the days, months, and years.
Photograph Copyright © 2008 Clipart Creations
Copyright © 2008 by Kassandra Radomski