Planet Earth Our Solar System Earth is part of a large physical system containing countless objects, all of which revolve around the sun. Eight spheres, called planets, are the largest objects in the solar system. Terrestrial planets have solid, rocky crusts; these four inner planets are Mercury, Venus, Earth, and Mars. Gas giant planets are more gaseous and less dense then the other planets; these four outer planets are Jupiter, Saturn, Uranus, and Neptune.  

Planet Earth Getting to Know Earth The atmosphere, hydrosphere, and lithosphere form the biosphere, the part of Earth that supports life for all people, animals, and plants. Atmosphere is a thin layer of gases that surround Earth and contains the air we breathe. Hydrosphere includes the liquid and frozen surface water, groundwater, and water vapor in and around oceans, lakes, and rivers on Earth. Lithosphere is the land or surface areas on Earth, including the continents, islands, and ocean basins.

Physical features of the earth For hundreds of millions of years, the surface of the Earth has been in motion. The Earth is composed of three main layers—the core, the mantle, and the crust. At the very center of the planet is a super-hot but solid inner core. Scientists believe that the inner core is made up of iron and nickel that is under enormous pressure. Surrounding the inner core is another band also composed of iron and nickel called the liquid outer core.

Even though the liquid outer core is composed of the same elements as the inner core, it is liquid because the pressure is not as great as it is in the inner core. Next to the outer core is a thick layer of hot, dense rock called the mantle. The mantle consists of silicon, aluminum, iron, magnesium, oxygen, and other elements. This dense mixture is soft enough to slowly but continually rise, cool, sink, warm up, and rise again, releasing 80 percent of the heat generated from the Earth’s interior.

landforms Underwater landforms are as diverse as those found on dry land. In some places the ocean floor is a flat plain. Other parts feature mountain ranges, cliffs, valleys, and deep trenches. Seen from space, Earth’s most visible landforms are the seven large  landmasses called continents. ( write down all 7 continents) Australia and Antarctica stand alone, while the others are joined in some way. Europe and Asia are parts of one landmass called Eurasia. A narrow strip of land called the Isthmus of Panama links North America and South America.

The continental shelf is an underwater extension of the coastal plain The continental shelf is an underwater extension of the coastal plain. Continental shelves slope out from land for as far as 800 miles (1,287 km). They descend gradually to a depth of about 660 feet (200 m), where a sharp drop marks the beginning of the continental slope. This area drops sharply to the ocean floor. Great contrasts exist in the heights and depths of the Earth’s surface. The highest point on Earth is in South Asia at the top of Mount Everest, which is 29,028 feet (8,848 m) above sea level. The lowest dry land point at 1,312 feet (400 m) below sea level is the shore of the Dead Sea in Southwest Asia. Earth’s deepest known depression lies under the Pacific Ocean, southwest of Guam in the Mariana Trench, a narrow, underwater canyon about 36,198 feet (11,033 m) deep.

Landforms Landforms are natural features at the surface of the earth’s lithosphere. Many of the earth’s landforms have a particular shape or elevation. Using Pg. RA2 write down the definition of each word and then draw a picture of it. Archipelago Cliff Glacier Isthmus Basin Continent Gulf Lake Bay Delta Harbor Lowland Canyon Divide Highland Mesa Cape Downstream Hill Mountain Canyon Escarpment Island Mountain Peak