Miracle Earth

Miracle Planet Earth By Wasif-ul-Aziz

Agenda Earth

Shape

of Earth Distance Between Earth and Sun Diameter of Earth Geological Layers of earth Heat Surface of Earth Atmosphere Magnetic Field Orbit and rotation. Axial tilt and seasons Natural and environmental hazards

Earth The earth is a planet full of life. There is a most harmonious balance of life in the sky, on the land and in the seas. Millions of animals, plants, insects and sea creatures, all with different structures, colours and features, live together on this special planet.

Shape of Earth 

The shape of the Earth is very close to that of an oblate spheroid.

Distance Between Earth and Sun 

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92,935,700 miles OR 1 AU (Astronomical Unit) = 1.495978706 x 10^11 meters.

Diameter of Earth 

The diameter of the earth at the equator is 7,926.41 miles (12,756.32 kilometers). But, if you measure the earth through the poles the diameter is a bit shorter - 7,901 miles (12,715.43 km). Thus the earth is a bit wider (25 miles / 41 km) than it is tall, giving it a slight bulge at the equator.

Geologic layers of the Earth Depth

Component Layer

km Earth cutaway from core to exosphere. Not to scale.

Density g/cm3

0–60

Lithosphere

—

0–35

... Crust

2.2–2.9

35–60

... Upper mantle

3.4–4.4

35–2890

Mantle

3.4–5.6

100–700

... Asthenosphere

—

2890–5100

Outer core

9.9–12.2

5100–6378

Inner core

12.8–13.1

Heat 

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Earth's internal heat comes from a combination of: Residual Heat from planetary accretion (about 20%). heat produced through radio active decay (80%). The major heat-producing isotopes in the Earth are potassium, uranium, and thorium.

Surface of Earth 

The Earth's terrain varies greatly from place to place. About 70.8% of the surface is covered by water, with much of the continental shelf below sea level. The submerged surface has mountainous features, including a globespanning mid-ocean ridges system, as well as undersea volcanoes, oceanic trenches, oceanic plateaus. The remaining 29.2% not covered by water consists of mountains, deserts, plains, plateaus, and other geomorphologies.

Atmosphere 

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The atmospheric pressure on the surface of the Earth averages 101.325 kPa, with a scale height of about 8.5 km. 78% nitrogen 21% oxygen The remaining 1 percent consists of argon and small amounts of other gases. The atmosphere also contains water vapor, carbon dioxide, water droplets, dust particles, and small amounts of many other chemicals released by volcanoes, fires, living things, and human activities.

Magnetic Field 

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he earth’s magnetic field is shaped roughly as a magnetic dipole, with the poles currently located proximate to the planet's geographic poles According to dynamo theory, the field is generated within the molten outer core region where heat creates convection motions of conducting materials, generating electric currents. These in turn produce the Earth's magnetic field. The convection movements in the core are chaotic in nature, and periodically change alignment. This results in fields reveal at irregular intervals averaging a few times every million years. The most recent reversal occurred approximately 700,000 years ago.

Orbit and rotation 

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The distance around Earth's orbit is 584 million miles (940 million kilometers). Earth travels in its orbit at 66,700 miles (107,000 kilometers) an hour, or 18.5 miles (30 kilometers) a second. Earth's orbit lies on an imaginary flat surface around the sun called the orbital plane. Earth takes 24 hours to spin completely around on its axis so that the sun is in the same place in the sky. This period is called a solar day. It only takes 23 hours 56 minutes 4.09 seconds for Earth to spin once. Earth takes 365 days 6 hours 9 minutes 9.54 seconds to circle the sun.

Axial tilt and seasons 

Because of the axial tilt of the Earth, the amount of sunlight reaching any given point on the surface varies over the course of the year. This results in seasonal change in climate, with summer in the northern hemisphere occurring when the North Pole is pointing toward the Sun, and winter taking place when the pole is pointed away. During the summer, the day lasts longer and the Sun climbs higher in the sky. In winter, the climate becomes generally cooler and the days shorter .

Natural resources and land use 

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The Earth provides resources that are exploitable by humans for useful purposes. Some of these are non-renewable resources, such as mineral fuels, that are difficult to replenish on a short time scale. Large deposits of fossil fuels are obtained from the Earth's crust, consisting of coal, petroleum, natural gas and methane clathrate. These deposits are used by humans both for energy production and as feedstock for chemical production. Mineral ore bodies have also been formed in Earth's crust through a process of Ore genesis, resulting from actions of erosion and plate tectonics.[132] These bodies form concentrated sources for many metals and other useful elements. The Earth's biosphere produces many useful biological products for humans, including (but far from limited to) food, wood, pharmaceuticals, oxygen, and the recycling of many organic wastes. The land-based ecosystem depends upon topsoil and fresh water, and the oceanic ecosystem depends upon dissolved nutrients washed down from the land.[133] Humans also live on the land by using building materials to construct shelters

Natural and environmental hazards 

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Large areas are subject to extreme weather such as tropical cyclones, hurricanes, or typhoons that dominate life in those areas. Many places are subject to earthquakes, landslides, tsunamis, volcanic eruptions, tornadoes, sinkholes, blizzards, floods, droughts, and other calamities and disasters. Many localized areas are subject to human-made pollution of the air and water, acid rain and toxic substances, loss of vegetation (overgrazing, deforestation, desertification), loss of wildlife, species extinction, soil degradation, soil depletion, erosion, and introduction of invasive species. A scientific consensus exists linking human activities to global warming due to industrial carbon dioxide emissions. This is predicted to produce changes such as the melting of glaciers and ice sheets, more extreme temperature ranges, significant changes in weather conditions and a global rise in average sea levels.

End of Presentation