Sunflowers are a sign of summer. But, astronomers can tell you the exact day and even the moment that summer officially begins. This moment in time is called summer solstice .
In 2009, in the Northern Hemisphere, summer solstice is on June 21 at 1:45 EDT (eastern daylight time).
While this is called the longest day of each year, it is only about one minute longer than the previous day. Actually summer solstice marks the point when daylight length begins to decrease.
Day length preceding the summer solstice increases. Day length following the summer solstice decreases until December 21 (first day of winter), when it starts to increase again. In the Southern Hemisphere, these dates are reversed, with summer starting in December and Winter in June.
For information about why the amount of daylight changes during the year, see SUMMER SOLSTICE.
For more information about the movements of the Earth, including rotation and revolution, and how they affect seasons, see Janice VanCleave's Geography for Every Kid.
Geography is a branch of science that encompasses all aspects of the earth's physical features and inhabitants. It is the study of almost anything about the earth–the distribution of its people, animals, and plants; land, sea, and air features; weather conditions–the list goes on. The difference between the study of geography and other sciences is that geography examines its subjects from a perspective of where they are located and what relatinship they have with the things around them. Other sciences tend to focus on subjects individually.
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