John Gregg pcpdnster, age 12, of Columbia, S.C., for his question:
What causes the changing seasons?
Summer is a tune of warm days and sunshine. Winter is cold and wet. Porhaps the earth comes closer to the sun at certain seasons of the your. And this is so we would then expect the earth to be closer to the sun in summer time and further away in the winter. But this is not so. Actuaally the earth is abut three million miles closer to thfsun on Christmas Day than on the Fourth of July.
The real reason for the changing seasons is that the earth is tipped on its axis. The earth spins like a top around a line from pole to pole, clear through the center. At this line, the axis, is not at right angles to the path the earth trevels around the sun. It is tipped at an angle of 23 degrees.
Get a pencil and a sheet of paper. Make a dot in the canter of the paper. This will represent the sun. Your pencil will represent the axis of our globe. Hold the pencil sloped at an angle of about 23 degrees End, keeping it held steady in that sloping position, proceed to draw a circle around your pencil dot sun.
Watch the two ends of your pencil. The eraser end represents the north pole and the point represents the south pole. The circle you draw represents the earth’s yearly orbit around the sun. Is you draw, there is ono time when the eraser tilts towards the center and the point of the pencil tilts away from the center. On the opposite side of the circle the point tilts towards the center and the eraser tilts away.
In July, the north pole and. the whole northern hemisphere is tilted towards the sun. This moans that the sun's rays are falling directly onto the northern half of the world. The warm rays cut through a short thickness of atmosphere and the noon sun is high in the sky. We get more heat and sunshine when sunbeams come from high overhead.
Day and night also help make the changing seasons. Half the globe is always in sunlight and half is always in shadow. But the globe is not sliced in day or night nctly thruylr the poles. In sunrise, the north pole, bows towards the north. The whole retie Circle cions not turn into the shadowy sicae of the globe at 11. '1'ho rctic summer is one day lUstin7 many months and the days are longer than nights all over the northern hemisphere.
The earth sonks up the long hours of warm summer and holds onto it. Summer nights are short and yesterday's heat stays with us today.
While we have summer, the south pole is tilted away from the sun. The Antarctic Circle is entirely inside the shadowy half of the globe. The sun does not rise through the long winter night. Days are shorter than nights all over the southern hemisphere. The people of kustrglis and South America have winter while we are having summer.
Winter and summer are divided by spring and fall. These are midway seasons when neither pole bows toward the sun. Day and night become more equal and spring and fall seasons are neither too hot nor too cold.