Although calendars often show September 21st as the first day of autumn, the autumnal equinox is actually September 22nd or 23rd. On this day, the sun's rays are directly over the earth at the equator. Many people throughout the world celebrate the coming of the new year in autumn.
Plants make their own food all summer.
They use water, a gas from the air called carbon dioxide, and sunlight. They get help from something called chlorophyll. The chlorophyll gives leaves their green color. Winter days are short and dry. Plants stop making food.