Solar System and the Earth-Sun Relationship Physical Systems Solar System and the Earth-Sun Relationship

Solar Energy Solar Energy: energy from the sun that reaches the Earth as light and heat. Without the sun, there would be no life on Earth. There are several factors that affect the amount of solar energy we receive.

Rotation Rotation: one complete spin of the Earth on its axis. Each rotation takes 24 hours. The Earth rotates from west to east, causing the sun to “rise” in the East and “set” in the West.

Rotation Why is rotation important? It allows the entire Earth to receive warm rays during the day, and cool off at night. Otherwise, one side would be too hot to live on, the other too cold.

Revolution Revolution: one elliptical orbit of the Earth around the sun. Each revolution takes 365 ¼ days. The quarter of a day is added every 4th year, creating a leap year.

Leap Year-FYI Every Leap Year is also the year for the Summer Olympics. Every Leap Year is also a Presidential Election Year.

Tilt The Earth is not perpendicular to the Sun. In fact, it tilts about 23.5°. This causes the North Pole to point towards the Sun at times, and away at other times.

The Seasons The tilt of the Earth as it revolves around the Sun causes the seasons. In summer, days are longer and warmer. In winter, days are shorter and cooler.

The Seasons The tilt also causes opposite seasons in the different hemispheres. So, when we are in summer, the Southern Hemisphere is in winter.

Winter Summer

Solstice Solstice: time of the year when the Earth’s poles are at the greatest angle towards or away from the sun. Solstices occur in the winter (December 21) and summer (June 21).

Equinox Equinox: occurs twice a year when the poles are not pointed towards the Sun. During these two days, there is about 12 hours of darkness and light. Equinoxes occur in the spring (March 21) and the fall (September 22).

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Closing Activity What is the difference between a solstice and equinox? What is the difference between rotation and revolution? What 3 factors influence how much solar energy is received in a place?

Class Work-Homework Diagram the Earth-Sun Relationship: (Use Pg. 30 in textbook) Assignment needs to be neat and colorful. Diagram must include: Tropic of Cancer, Tropic of Capricorn, Equator, North Pole, South Pole, Label Solstices and Equinoxes, Provide Dates Briefly describe how rotation, revolution, and tilt affect life here on Earth.