World Geography TodayChapter 2 Earth in Space Preview Section 1: The Solar SystemThe Solar System Section 2: Earth-Sun RelationshipsEarth-Sun Relationships Section 3: The Earth SystemThe Earth System Chapter Wrap-Up

World Geography TodayChapter 2 Read to Discover What is Earth’s position in the solar system? How do rotation and revolution affect Earth? Section 1: The Solar System

World Geography TodayChapter 2 Sun Mercury Venus Earth Mars Uranus Neptune Jupiter Saturn Section 1: The Solar System

World Geography TodayChapter 2 One of eight planets Third planet from the Sun Fifth-largest planet In elliptical orbit around the Sun Section 1: The Solar System Earth’s Position in the Solar System

World Geography TodayChapter 2 Rotation and revolution affect the amount of solar energy Earth receives at different locations. Rotation of Earth on its axis produces day and night. Revolution around the Sun takes one year. Revolution and the tilt of Earth on its axis determine seasons. Section 1: The Solar System Rotation and Revolution

World Geography TodayChapter 2 Read to Discover How does the angle of the Sun’s rays affect the amount of solar energy received at different locations on Earth? What are solstices and equinoxes? Section 2: Earth-Sun Relationships

World Geography TodayChapter 2 Direct vertical rays of sunlight concentrate solar energy in a smaller area, making more heat. Angled rays spread solar energy out, making less heat. Earth’s tilt makes direct rays most common near the equator and less common at high latitudes. Change in the Earth’s tilt creates seasons. Section 2: Earth-Sun Relationships Angle of the Sun’s Rays

World Geography TodayChapter 1World Geography TodayChapter 2 Solstice Time twice a year when Earth’s poles point at their greatest angle toward or away from the Sun Equinox Time twice a year when Earth’s poles are both at a 90° angle from the Sun Section 2: Earth-Sun Relationships

World Geography TodayChapter 2 Solstices—About December 21 and June 21  Earth’s poles tilted toward or away from the Sun  Longest or shortest days of the year, depending on hemisphere Equinoxes—About March 21 and September 22  Earth’s poles not tilted toward or away from the Sun  Equal amount of sunlight in both hemispheres Section 2: Earth-Sun Relationships Solstices and Equinoxes

World Geography TodayChapter 2 Read to Discover What are Earth’s four spheres? How is Earth’s environment unique in the solar system? Section 3: The Earth System

World Geography TodayChapter 2 Atmosphere—Envelope of gases surrounding Earth; least dense and outermost sphere Lithosphere—Solid crust of the planet; forms continents, islands, and ocean floor Hydrosphere—Earth’s water; 70 percent of Earth’s surface, including water in liquid, solid, and gaseous forms Biosphere—All life-forms; overlaps other three spheres Section 3: The Earth System Earth’s Four Spheres

World Geography TodayChapter 2 No other planet in the solar system has such a complex environment. Earth’s environment is the key to human survival and quality of life. Section 3: The Earth System Earth’s Unique Environment