Length of Daylight

Two graphs, one depicting the amount of daylight during the 2020 equinoxes in Des Moines, Iowa, and one depicting the amount of daylight on four different dates in December 2020 illustrate how the amount of daylight changes at different times of the year. The graphs support the pattern of daylight in the northern hemisphere from the longest period of daylight hours on the summer solstice in June to the shortest period of daylight hours on the winter solstice in December.

• What causes the patterns of day and night?

• Why do we have seasons?
• Why do we have more or less hours of daylight at different times of the year?

Students could:

• Record patterns of light and dark at different times of day throughout the school year in a graphic organizer.
• Track the position of the sun across the sky throughout the day.
• Use weather forecast data to compare the times of sunset throughout the year.
• Keep a moon journal to track the phases of the moon and its position in the sky.

• PBS Learning Media | Bringing the Universe to America's Classrooms: Sunrise and Sunset: Summer and Winter: A three-minute time-lapse video of the sun’s movement across the sky in summer and winter and how that affects the amount of daylight.
• PBS Learning Media | Bringing the Universe to America's Classrooms: 30 Sunsets - Summer to Winter: A brief video that tracks the time of sunset from the summer solstice to the winter solstice.
• Time and Date | Sunrise, Sunset, and Day Length - Des Moines, Iowa: List of sunrise and sunset data and an interactive sun graph for Des Moines, Iowa.