Jane Hanneman, age i4, of Spokane, WA., for her question:

How did the Egyptians predict the flooding of the Nile?

Summer days are long, and the noon sun climbs high in the sky. Winter days are shorter, and the noon sun is lower in the sky. If we recorded the daily path of the sun enough times, We could predict the changing seasons. Early astronomers also learned to predict the seasons from the changing parade of stars over the night sky.

This story goes back before the dawn of history. We tell time from the movements of the heavenly bodies, and early astronomers watched the heavens for ages before they learned how to record the passing of time. The Egyptians were sowing their crops in the muddy flood waters of the Nile, 7000 years ago. Already their astronomers had figured out how to predict the season of flooding waters.

Their star, perhaps their favorite star, was Sirius. In the winter this brightest of all stars rides over the night sky at the heels of the constellation Orion, the Hunter. There are, of course, always stars in the sky. During the day they are invisible because they are out dazzled by the radiant sun. In the summer, Sirius rides over the daytime sky.

In early winter, Sirius and its starry companions rise low in the east as the sun sets in the west. Each sunset reveals them a little higher in the sky. In the spring, they are in the west, ready to sink with the setting s wz. All through the summer, they are stars of the daytime. In late summer, Sirius is ready to rise with the sun. Long ago, in the southern latitudes of Egypt, the seasons of Sirius were slightly different. But its yearly travels told the astronomers when to expect the flooding of the Nile.

They knew from years of experience that the great river begins to rise when Sirius rises with the sun. For several weeks, they saw the brilliant star in the sky at dawn. This was the time to arouse the farmers, the time to prepare for sowing. Soon the great river would slop over its banks and spread its rich and muddy waters over the land.

The Egyptians, it seems, were grateful to the Star Sirius. To them. It represented a god, and, perhaps because it was the brightest Of Stars, they called it the second sun and made it ruler of the starry night. Later, the Romans called it the Dog Star. To them it was an evil star, for its period of rising with the sun was their sultry period of scorching summer. The Romans named this season the Dog Days.