Miss Debra Pellegrino's second grade class at Ben Franklin School in Indiana, Pa., for their question:
WHEN DOES FALL START?
Each year is divided into four seasons: spring, summer, autumn and winter. Each season lasts about three months and each one has its own distinctive features. The seasons are reversed in the Northern and Southern hemispheres. It is summer during June, July and August in the Northern Hemisphere, while it is winter during those three months in the Southern Hemisphere.
Autumn this year started on Sept. 22 in the Northern Hemisphere. The starting day varies from year to year, with the season starting on Sept. 23 in 1978 and 1979, and then going back to Sept. 22 for 1980 and 1981.
Many people call the season fall. This name came about, no doubt, because it is the season of falling leaves. The temperatures are usually rather pleasant during the days for the three month season that will end on Dec. 20 (winter this year starts on Dec. 21). As winter approaches the days will get cooler with cold rain and snow for many of the Northern Hemisphere's sections.
Changing seasons are caused by the earth's changing position in relation to the sun. We know exactly from the earth's motion when one season ends and the next one begins.
The first day of autumn is called the autumnal equinox. On this day the sun appears directly above the equator and the day is divided almost exactly into 12 hours of daylight and 12 hours of darkness.
A similar event happens in March when spring starts. The day is called the vernal equinox.
In the Northern Hemisphere the sun is at its highest on June 20 or 21 for the start of summer. The day is called the summer solstice. The shortest day falls on either Dec. 21 or 22 when winter starts. This is called the winter solstice.
Pleasant autumn weather doesn't last too long in the polar region of the Northern Hemisphere because extremely cold weather begins early. In the regions closer to the equator, seasonal changes are not great.
In most of North America autumn is usually very beautiful. It's harvest time in many locations and the days are generally warm and sunny. The nights come through with a refreshing crispness about them.
The relative position of the sun and the earth, and therefore the seasons, keeps changing while the earth circles the sun. When the North Pole slants toward the sun, the Northern Hemisphere receives the most sunlight and it is summer there. When the pole slants away from the sun, the Northern Hemisphere receives the least sunlight and it is winter. Autumn begins when the pole starts to slant away from the sun.