Our planet EARTH
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Earth formed about 4.5 billion years ago and is the only known planet that supports life. It has three main layers - a crust, mantle, and core. The crust ranges from 5-70 km deep and has both continental and oceanic parts. Below the crust is the thickest layer, the mantle, which extends to a depth of 2,890 km and is composed of silicate rocks. The innermost layer is the core, with a solid inner core of iron and nickel around 1,220 km wide and a liquid outer core that creates Earth's magnetic field.
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Our planet EARTH
- 1. Our Planet - EARTH 1
- 2. An Introduction to Earth Earth, the planet on which we live was formed about 4.5 billion years ago. It is fifth largest in the solar system and first largest in the inner planets of the solar system. It has the 3rd position from the sun and 6th position from outer planets. It is known as the unique planet because it is the only planet in the universe which is known to have life. 2
- 3. It’s surface has water, land and is surrounded by a blanket of air known as Atmosphere. These things help in the possibility of life. It’s position from the sun also help in possibility of life because if it is too near the sun, so it will be having very hot temperature and if it is too far from the sun, so it will be having very cold temperature. When astronauts first saw the earth from the space, it looked blue in color because of the presence of water all over the surface. So, astronauts named the earth ‘Blue Planet’ or ‘Watery Planet’. It is also known as ‘Terra’. It is the only in the solar system which is not named after a mythology deity. 3
- 4. Motions of the Earth The Earth is having two types of motions:- 4 Motions Rotation Revolution
- 5. Rotation Earth has an imaginary line on which it rotates, known as Axis. Earth’s orbit is slanting which makes unequal days and nights on earth. When the earth rotates on its axis, it is called Rotation. Rotation causes days and nights on earth. Earth takes 24 hours to complete one rotation. Earth takes rotation from west to east. Earth has the speed of 30 km of rotation on equator while on poles it has 0 km. Earth completes one rotation in 23 hours, 56 minutes and 4.1 seconds. 5
- 6. Revolution Earth has an imaginary line on which it goes around the sun, known as Orbit. Earth’s orbit is oval which brings the earth near the sun and far from the sun. when the earth goes around the sun, it is called Revolution. Revolution causes changes in the seasons on the earth. Earth takes 365 days, 5 hours, 48 minutes and 56 seconds (3651/4 days) to complete one revolution. Revolution also runs from west to east. 6
- 7. Difference between Rotation & Revolution Rotation • The movement of the earth on it’s axis is called Rotation. • Rotation causes days and nights. • Rotation is done in 23 hours, 56 minutes and 4.1 seconds. Revolution • The movement of the earth around the sun is called Revolution. • Revolution causes seasons. • Revolution is done in 365 days, 5 hours, 48 minutes and 56 seconds. 7
- 8. Layers of the Earth Earth has three types of layers, they are:- 8 Layers Crust Mantle Core
- 9. Crust The crust ranges from 5–70 km (3–44 miles) in depth and is the outermost layer. The crust is of two types:- 9 Crust Continental Oceanic
- 10. The thin parts are the oceanic crust, which underlie the ocean basins (5–10 km) and are composed of dense (mafic) iron magnesium silicate igneous rocks, like basalt. The thicker crust is continental crust, which is less dense and composed of (felsic) sodium potassium aluminums silicate rocks, like granite. The temperature of the Earth crust range from 500 °C (900 °F) to 1,000 °C (1,800 °F). Temperature generally increases with an increase in depth and the average temperature of Earth. 10
- 11. Mantle 11 The Mantle is the between layer of the earth and the thickest layer of the earth. Earth's mantle extends to a depth of 2,890 km. The mantle is composed of silicate rocks that are rich in iron and magnesium relative to the overlying crust. The temperature of the mantle is 3,700 degrees Celsius. Convection of the mantle is expressed at the surface through the motions of tectonic plates.
- 12. Core Core is the innermost layer of the earth. The core is of two types:- 12 Core Inner Outer
- 13. Inner Core The inner core of the Earth, its innermost part, is a primarily solid ball with a radius of about 1,220 km (760 mi), according to seismological studies. This is about 70% of the length of the Moon's radius. It is believed to consist primarily of an iron–nickel alloy, and to be about the same temperature as the surface of the Sun: approximately 5700 K (5430 °C). The Earth was discovered to have a solid inner core distinct from its liquid outer core in 1936, by the seismologist Inge Lehmann Based on the relative prevalence of various chemical elements in our solar system, the theory of planetary formation, and constraints imposed or implied by the chemistry of the rest of the Earth's volume, the inner core is believed to consist primarily of a nickel-iron alloy known as NiFe. 13
- 14. Outer Core The outer core of the Earth is a liquid layer about 2,266 km (1,408 mi) thick composed of iron and nickel which lies above the Earth's solid inner core and below its mantle. Its outer boundary lies 2,890 km (1,800 mi) beneath the Earth's surface. The transition between the inner core and outer core is located approximately 5,150 km (3,200 mi) beneath the Earth's surface. The temperature of the outer core ranges from 4400 °C (8000 °F) in the outer regions to 6100 °C (11000 °F) near the inner core. Without the outer core, life on Earth would be very different. Convection of liquid metals in the outer core creates the Earth's magnetic field. 14
- 15. The Story of Earth As you know, the earth was formed about 4.6 billion years ago, it’s story starts. The Earth will live 4.5 million years more. If you want to watch the story of the earth, here’s a hyperlink. D:VideosThe Story of Earth.mp4 15
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